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October 1, 1873


APPEALS from the Circuit Court for the Southern District of New York, in which court R. A. Tilghman filed two bills in equity against R. G. Mitchell, under a patent granted to him the said Tilghman, for a process for making fat-acid and glycerin from natural fat; one bill having been filed during the first term of the patent, and the other under the extended term of the same patent.

In both cases final decrees were given in favor of Tilghman; and the defendant, Mitchell, took these appeals.

The bill set forth the grant of letters-patent to Tilghman, October 3d, 1854, for fourteen years from January 9th, 1854, the reduction of the patented inprovement to use, and the infringment by Mitchell.

The invention claimed by Tilghman may be stated, in general terms, to be based upon the discovery that if water be heated to a high degree, and at the same time retained in a close vessel so that it cannot pass into the state of steam, but must remain in the liquid state, it will, while in such highly heated liquid state, possess a peculiar property of separating natural fat into its chemical constitutents, glycerin and fat-acids. He undertook to claim the employment of water in the liquid state, heated and under the pressure necessary to retain it in the liquid state as the decomposing agent. He asserted that prior to his discovery and invention, no one had ever known, used, or described the employment of highly heated water retained in the liquid state by pressure as such decomposing agent, and that under the law if he set forth this newly discovered decomposing power of liquid water heated and under pressure, and exhibited in his specification one mode of practically applying it, he was entitled to the exclusive use of this decomposing agent in treating facts for the purpose of separating them into fat-acids and glycerin.

To understand the questions at issue in this case, and passed upon by the court, there is first to be considered the phenomenon of heating water, &c., its behavior and properties when heated.

Water when heated in an open vessel at the surface of the earth passes into a state of vapor, at a temperature of 212° of Fahrenheit's thermometer; the waters expanding over eighteen hundred times in passing into steam. It is impossible to retain water in a liquid state, in an open vessel, after it has reached that temperature. If the vessel in which the water is heated, however, be overed, and the cover be fastened down, the water can be heated to any temperature whatever, and will still remain in the liquid state. The tendency of the water to pass into vapor increases with the degree of heat applied to it, and there must, therefore, be a proportionate pressure or restraint by the inclosing vessel on the heated water to overcome this expansive tendency, or tendency to pass into a state of a vapor.

Vessels in which water could be heated to any desired temperature, and the water still retained in the liquid state, were known in the arts, and called 'digesters.'

To understand matters further a brief statement of the art of treating fat is necessary.

Fats obtained from various sources differed much in hardness and fusibility, and each variety was formerly supposed to be an entirely different article. About 1816, Braconnot, a French chemist, discovered that all natural fats were merely mechanical mixtures, in various proportions of fats entirely solid and hard, now called stearin, with a more fluid fat or oil, called olein. He found that simple pressure very slowly applied, squeezed out the more fluid part, and that the remainder made harder candles. But the process of separation by pressure was difficult and imperfect.

Chevreul, in 1825, discovered that all fats were chemical compounds of a substance called glycerin, with fatty bodies having slight acid characters called fatty acids; that fatty acids were of different degrees of fusibility, and that when the glycerin was separated from fats, the fatty acids could be more rapidly and perfectly pressed so as to get out the hardest fatty acids for candles; and he patented a chemical process of separating these fatty acids from glycerin.

His process consisted of two distinct stages:

1. The manufacture of natural fat into soap, by boiling lime or other alkali with the fat, in which case fourteen pounds of lime were used to one hundred pounds of fat.

2. The decomposition of the soap so produced into fat-acid by the use of two pounds of sulphuric acid to each pound of lime.

Soap had always previously been made by boiling the fat and solution of alkali together, and Chevreul suggested that this production of soap could be expedited by boiling the fat and the solution of alkali together under pressure. He did not, however, suggest that water alone, heated and under pressure, would of itself decompose neutral fat into a fat-acid and glycerin, but expressly mentioned alkali and sulphuric acid as the decomposing agents.

Another mode of separating free fat-acids was devised, which was called decomposition by sulphuric acid distillation.

This process was invented and used for producing fat-acid only, and not glycerin; the glycerin being destroyed by the process. It was asserted by Tilghman that this process differed from his:

1. In that the result produced was different, viz., fat-acid only, while his, Tilghman's, produced simultaneously both fat-acid and glycerin;

2. In that it required sulphuric acid to decompose the fat into fat-acid;

3. In that it did not depend for its efficiency on the use of highly heated water in the liquid state, retained in such state by pressure;

4. In that it was a process of distillation.

We must view here also the attempted decomposition by steam.

It was from time to time attempted, prior to Tilghman's alleged invention, to decompose neutral fat into fat-acid by distillation in a current of steam, but it was asserted by Tilghman that it was an unsuccessful and abandoned experiment, and had never come into use; and that even if it had been successful it differed in every way from his process. Among other ways,

In not producing glycerin as a result;

In not depending upon, or even allowing of, the presence of highly heated water under pressure;

In that it was a process depending on vaporization and subsequent condensation of the fat-acids;

In that the apparatus absolutely necessary for the distillation process was such as to render the execution of the hot-water process of him, Tilghman, in the same utterly impossible.

Tilghman asserted that he had made the discovery–not that heat alone would decompose fats into fat-acid and glycerin, nor that the presence of water was necessary whem chemicals are used to decompose fats into fat-acid and glycerin–but merely that water in a liquid state, heated to a high degree of temperature while inclosed in a strong vessel, so as to prevent its passing into steam, would of itself and without the aid of chemicals separate natural fat into its constitutent elements, fat-acids and glycerin. Having made, as he alleged, this discovery of a new chemical decomposing property of water highly heated and retained in the liquid state by pressure, Tilghman, in his patent, announced it, and, as will be seen directly, also described two modes of carrying out his process based thereon.

In the alkaline saponification processes, which were in use prior to Tilghman's invention, various forms of closed boilers, provided with safety valves, were known. It was also known that fat and water would tend to remain unmixed in a boiler, and therefore agitators or circulators, for preserving a mixture or intimate contact between the fat and lime and water during the process of alkaline saponification, under pressure, were also in use.*fn1

The specification, in the patent, ran thus:

'Be it known that I, Richard Albert Tilghman, of Philadelphia, have invented a new and improved mode of treating fatty and oily bodies, and I hereby declare that the following is a full and exact description thereof.

'My invention consists of a process for producing free fat-acids and solution of glycerin from those fatty and oil bodies of animal and vegetable origin which contain glycerin as their base. For this purpose, I subject these fatty or oily bodies to the action of water at a high temperature and pressure, so as to cause the elements of those bodies to combine with water, and thereby obtain at the same time free fat-acids and solution of glycerin. I mix the fatty body to be operated upon with from a third to a half of its bulk of water.

'And the mixture may be placed in any convenient vessel in which it can be heated to the melting-point of lead, until the operation is complete. The vessel must be closed and of great strength, so that the requisite amount of pressure may be applied to prevent the conversion of the water into steam.

'The process may be performed more rapidly and also continuously by causing the mixture of fatty matter and water to pass through a tube or continuous channel, heated to the temperature already mentioned; the requisite pressure for preventing the conversion of water into steam being applied during the process, and this, I believe, is the best mode of carrying my invention into effect.

'In the drawing hereunto annexed are shown figures of AN apparatus for performing this process speedily and continuously, but which apparatus I do not intend to claim as any part of my invention.

'Figure 1 of the said drawing is a vertical section of this apparatus, and Figure 2 shows the various parts of the apparatus in horizontal section: similar parts in these figures being marked with similar letters of reference.

'I place the fat or oil in a fluid state in the vessel, A, with from one-third to one-half its bulk of warm water; the disk or piston, B, perforated with numerous small holes, being kept in rapid motion, up and down, in the vessel, A, causes the fat, or oil and water, to form an emulsion, or intimate mechanical mixture. A force-pump, C, like those in common use for hydraulic presses, then drives the mixture through a long coil of very strong iron tube, D, D, D, D, which, being placed in the furnace, E, E, E, E, is heated by a fire, F, to about the temperature of melting lead. From the exit end, G, of the heating tubes, D, D, D, D, the mixture, which has then become converted into free fat-acids and solution of glycerin, passes on through another coiled iron tube, H, H, H, immersed in water, by which it is cooled down from its high temperature to below 212° Fahrenheit, after which it makes its escape through the exit-value, I, into the receiving vessel.

'The iron tubes I have employed and found to be convenient for this purpose, are about one inch external diameter, and about half an inch internal diameter, being such as are in common use for Perkins's hot-water apparatus. The ends of the tubes are joined together by welding to make the requisite length, but where welding is not practicable, I employ the kind of joints used for Perkins's hot-water apparatus, which are now

well known. The heating-tube, D, D, D, D, is coiled several times backwards and forwards, so as to arrange a considerable length of tube in a moderate space. The different coils of the tube are kept about a quarter of an inch apart from each other, and the interval between them is filled up solid with cast iron, which also covers the outer coils or rows of tubes to the thickness of half or three-quarters of an inch, as shown in Figure 2. This casing of metal insures a considerable uniformity of temperature in the different parts of the coil, adding also to its strength, and protecting it from injury by the fire.

'The exit-valve, I, is so loaded that when the heating tubes, D, D, D, D, are at the desired working temperature, and the pump, C, is not in action, it will not be opened by the internal pressure produced by the application of heat to the mixture; and, therefore, when the pump, C, is not in action, nothing escapes from the value, I, if the temperature be not too high. But when the pump forces fresh mixture into one end, J, of the heating tubes, D, D, D, D, the exit-valve, I, is thereby forced open to allow an equal amount of the mixture, which has been operated upon, to escape out of the cooling tubes, H, H, at the other end of the apparatus. No steam or air should be allowed to accumulate in the tubes, which should be kept entirely full of the mixture. For this purpose, whenever it may be required, the speed of the pump should be increased, so that the current through the tubes may be made sufficiently rapid to carry out with it any air remaining in them.

'Although the decomposition of the neutral facts by water takes place with great quickness at the proper heat, yet I prefer that the pump, C, should be worked at such a rate in proportion to the length or capacity of the heating tubes, D, D, D, D, that the mixture, while flowing through them, should be maintained at the desired temperature for ten minutes before it passes into the refrigerator or cooling parts, H, H, of the apparatus.

'The melting-point of lead has been mentioned as the proper heat to be used in this operation, because it has been found to give good results. But the change of fatty matters into fat-acid and glycerin takes place with some materials (such as palm oil) at, or below, the melting-point of bismuth, yet the heat has been carried considerably above the melting-point of lead without any apparent injury, and the decomposing action of the water becomes more powerful as the heat is increased. By starting the apparatus at a low heat, and gradually increasing it, the temperature giving products most suitable to the intended application of the fatty body employed, can easily be determined.

'To indicate the temperature of the tubes D, D, D, D, I have found the successive melting of metals and other substances of different and known degrees of fusibility to be convenient in practice; several holes, half an inch in diameter, and two or three inches deep, are bored into the solid parts of the castings surrounding the tubes, each hole being charged with a different substance. The series I have used consist of tin, melting about 440° F.; bismuth at about 510° F.; lead at about 612° F.; and nitrate of potash at about 660° F. A straight piece of iron wire, passing through the side of the furnace to the bottom of each of the holes, enables the workmen to feel which of the substances are melted, and to regulate the fire accordingly. It is important, for the quickness and perfection of the decomposition, that the oil and water, during their entire passage through the heating tubes, should remain in the same state of intimate mixture in which they enter them. I therefore prefer to place the series of heating tubes in a vertical position, so that any partial separation which may take place, while the liquids pass up one tube, may be counteracted as they pass down the next. I believe that it will be found useful to fix at intervals, in the heating tubes, diaphragms pierced with numerous small holes, so that liquids, being forced through these obstructions with great velocity, may be thoroughly mixed together.

'I deem it prudent to test the strength of the apparatus by a pressure of ten thousand pounds to the square inch, before taking it into use; but I believe that the working pressure necessary in using the heat I have mentioned will not be found to exceed two thousand pounds to the square inch.

'When it is desired to diminish the contact of the liquids with iron, the tubes or channels of the apparatus may be lined with copper. The hot mixture of fat-acids and solution of glycerin which escapes from the exit-valve of the apparatus separates by subsidence. The fat-acids may then be washed with water, and the solution of glycerin concentracted and purified by the usual means.

'The fat-acids thus produced may, like those obtained by other methods, be used in the manufacture of candles and soaps, and applied to various purposes, according to their quality; and, when desired, they may also be first bleached by chemical agents, or purified by distillation, in a current of steam or in a vacuum, as is now well understood. I prefer that the fatty bodies should be previously deprived, as far as practicable, of such impurities as would cause the discoloration of the fat-acids produced; but when the fat-acids are to be finally purified by distillation this preliminary purification is of less importance.

'When the sulphuric acid, nitrous fumes, or other corrosive agent shall have been used for purifying, hardening, or otherwise preparing the fatty body to be operated upon, I take care that all traces of it shall be washed out, or neutralized, before passing it through the apparatus.

'Some fatty bodies (particularly when impure) generate, during the process, a portion of acetic or other soluble acid, which might tend to injure the iron tubes; in such cases, I add a corresponding quantity of alkaline or basic matter to the water and oil before they are pumped into the tubes.

'Having now described the nature of my said invention, and the manner of performing the same, I hereby declare that

'I claim as of my invention, the manufacturing of fat-acids and glycerin from fatty bodies by the action of water at a high temperature and pressure.


The answers to the bill of Tilghman, which set forth his patent, denied that Tilghman had applied his improvement to practical use;

Alleged that the manufacturing of fat-acids and glycerin from fatty bodies by the action of water at a high temperature and pressure, cannot be accomplished so as to be practically useful, if it can at all, by the method and apparatus described in said letters-patent;

Alleged that all attempts to carry on the manufacture of fatty acids by means of the apparatus and method described in said letters-patent had failed;

Denied that the defendant had been using the improvement of Tilghman, or 'any method in construction or operation substantially the same, otherwise than was thereinafter alleged,' but admitted that he 'used water at a high temperature, and steam, and such pressure as arises from the expansive force of hot water or steam in a close vessel, under and in pursuance of a patent of Wright & Fouch e, January 25th, 1859;'

Alleged that 'the action of water highly heated in a close vessel upon very many substances to decompose them, and upon fats and oils,' was, prior to Tilghman's invention, well known to chemists, &c., and was described in printed publications;

Alleged that before the invention of Tilghman 'the use of a close vessel of such strength as to resist the pressure of the water when heated, or any needed pressure when using water to decompose other substances, was known to and practiced by men of science and manufacturers in the United States and elsewhere;'

Alleged that the said quality of highly heated water thus used is an elementary principle, and not patentable;

Alleged that the mode and means described in the specification as the best means of carrying the invention into effect was dangerous, owing to the degree of heat required.

It also referred to numerous prior patents, and contained extracts from publications to show that Tilghman's invention had been anticipated. Among the extracts were:

1st. Extracts showing use of digesters, for heating water to high temperature and still retaining it in a liquid state;

2d. Extracts showing use of digesters for rendering raw fat or removing the membranous and cellular matter, and thus purifying it;

3d. Extracts from text-books and writers, stating generally that neutral fats can be decomposed into fat-acids and glycerin, and that in the act of decomposition the elements of the water are taken up by the fat-acids and glycerin;

4th. Extracts to show that alkaline saponification decomposes neutral fat into soap and glycerin, which soap can afterwards be decomposed into fat-acid; and also to show that the alkaline saponification can be better effected in a close vessel under pressure;

5th. Extracts stating that fats can be distilled in the presence of steam into fat-acids, which are passed over as vapors and condensed in the still.

The patent of Wright & Fouch e, dated January 25th, 1859, under which the defendant, Mitchell, in his answer as above condensed, asserted that he was working, was thus:'TO ALL TO WHOM IT MAY CONCERN:

'Be it known that we, Robert Alfred Wright, civil engineer, and Louis Jules Fouch e, steam-boiler maker, of Paris, in the empire of France, have invented 'a new apparatus, destined to produce chemical decompositions by means of superheated steam and water;' and we do hereby declare that the following is a full, clear, and exact description of the same, reference being had to the annexed sheet of drawings, making a part of the same.

'The apparatus, which is the object of the present patent to secure, is susceptible of several industrial applications; but as it is chiefly intended for the decomposition of fatty substances into fatty acids and glycerin, we will describe it as applied to that purpose.

'This invention is represented in the annexed drawing, which shows the elevation of the apparatus complete.*fn2

'The dimensions of the apparatus may vary with the various purposes to which it may be applied.

'a is a metal (iron or copper) boiler, of any form whatever, placed in a furnace, in order to be heated by a naked fire; this boiler has sides sufficiently strong to resist a pressure of from ten to twenty atmospheres;*fn3 it is of a variable capacity, according to the requirements of the manufacture, and it may have its interior lined with lead, or by any other metal which will not be attacked by the fatty bodies which are to be introduced and produced therein; b, hearth; c, ashpit; d, dipping-pipe, furnished with a cock to empty the apparatus by pressure; e, e, manhole, serving for cleaning the cylindrical vessel a, and for the introduction of substances, if required; f, metal tube (of iron or copper) connecting the bottom of the boiler a with the bottom of the cylinder h; g, metal tube of ascension, conducting the superheated water from the boiler a to the upper part of cylinder h. This tube is terminated in the interior of the cylinder h by a rose-jet, or, more simply, holes are made in the extremity, so as to distribute the water uniformly in the cylinder h, and to insure a molecular or finely subdivided contact between the superheated water and the substance submitted to the operation; h, iron or copper upper cylinder, which should, like boiler a, be able to resist a pressure of from ten to twenty atmospheres. The cylinder h receives the substances to be treated; i, funnel, furnished with a tube and with a cock, serving for the introduction of the substances to be treated into the cylinder h; that is, when this substance is of such a nature

as to be introduced through a small aperture; k, manhole, serving for cleaning the cylinder h, and for the introduction of substances to be treated which cannot pass through the funnel i; l, safety-valve; m, manometer or pressure-gauge, indicating the pressure in the whole of the apparatus; n, n, cocks serving to indicate the height and level of the substance and of the water in cylinder h; , cock serving to empty the cylinder when the operation is completed.


'Supposing everything arranged as shown in the drawing, then, in order to decompose fatty substances into fatty acids and into glycerin, the boiler a is completely filled with water. The cylinder h is filled with water up to one-third of its height, and it is then filled up to the level of the upper cock with the fatty bodies to be decomposed. The introduction of the fatty bodies takes place, as we have said, either through the funnel i or by the manhole k. The boiler a is then gradually heated till the pressure-gauge indicates a pressure of from ten to twenty atmosphers, according to the nature of the substances submitted to the operaton, when the following takes place:

'The superheated water in the boiler a acquires an ascending motion on account of the difference in the temperature of the two capacities a and h; a current is thus created, whence it results that the heated water in boiler a ascends through the tube g into the cylinder h, and being forcibly driven out through the holes in the rose-jet, passes through the fatty bodies and descends again through the tube f to the bottom of the boiler a, where it is again warmed, in order to recommence its ascending motion, and so on.

'When this operation has been thus continued during a length of time which may vary from five to eight hours, according to the nature of the fatty bodies operated on, and also according to the variation of pressure (varying from ten to twenty atmospheres) the fatty bodies are decomposed into glycerin, which remains dissolved in the water, and into fatty acids, which float in the cylinder h. The contents are now emptied out and separated from each other at the same time.

'In conclusion, we would remark that we are aware that: Firstly, the decomposition of fatty bodies by water under the influence of heat and of pressure is a well-known scientific fact: Water is substituted for the organic basis. It forms a perfect and fixed combination with the fatty acids, while the glycerin is dissolved in the excess of water. Secondly, that as this chemical action takes place under the influence of a weak affinity, it is necessary, in addition to the abovenamed physical and chemical conditions, to insure a perfect molecular agitation of the whole mass; and that we wish it to be understood that what we wish to claim and establish as of our invention consists of an apparatus wherein the water and the fatty matters are heated separately in two different boilers. The first boiler is heated by the source of heat, while the second boiler is heated by the first boiler.

'In these boilers the agitation necessary for the chemical action and combination is produced by the pressure of the heated water in the first boiler. This water circulates continuously from this first boiler to the second boiler, and from the second boiler to the first, in a continuous and self-acting or automatic manner, without interruption. The characteristics of our apparatus are, that it produces agitation by circulation alone, a continuous and automatic circulation, produced by the pressure of water.

'Lastly, our apparatus effects its chemical action in a continuous manner, without the aid of any manual or other assistance.'

'CLAIMS. Having described the nature of our invention and the manner in which the same is to be performed, we do not claim the application of superheated water for decomposing fatty bodies, nor the form of the apparatus above described, which may vary somewhat according to conditions and circumstances; but what we claim as our invention is, producing a continuous automatic circulation of highly heated water, in a very finely divided state, through the bodies under treatment, by means of an apparatus constructed and employed substantially as herein shown and described.'

Tilghman insisted that the use of highly heated water under pressure to decompose neutral fats into fat-acids and glycerin was an infringement of his patent, no matter what particular form of apparatus might be used, or what particular temperature adopted, and no matter what particular device might be adopted to maintain the intimate mechanical mixture of the fat and water during the decomposing operation; these last being obvious matters of detail, susceptible of infinite variety.

He contended that Mitchell's infringement consisted in using highly heated water with neutral fat in a close vessel, and restraining or confining it there under pressure so as to preserve the water while heated in a a liquid state, and by means of this highly heated liquid water to produce fat-acid and a solution of glycerin.

Mitchell, on the contrary, asserted that heat alone will decompose fats into their elements; that the decomposition is effected by temperatures varying from about 510° F., the melting-point of bismuth, to 610° F., the melting-point of lead; that these were the very temperatures named by Tilghman as required in his process; but that in the very act of separation they will be destroyed unless some base be present to unite with these elements; that this destruction so produced was the burning up, in fact, of the fat by heat; that this effect was known to Tilghman; and that his invention consisted merely in using heat to decompose the fat by sheer heat, and to supply, at the instant of decomposition, water to prevent the burning up or destruction of the elements produced; that the single idea of Tilghman's patent was the use of great heat to decompose and a contrivance for immediately presenting particles of the aqueous agent to fix and reunite into the new forms the decomposed elements; that he did this by making an emulsion or mechanical mixture of fat and water; that he called for a vessel of great strength, and proposed to work under a pressure of 2000 pounds to the square inch; and that he loaded the safety-valve to prevent the conversion of water into steam.

Mitchell therefore contended that from the very purpose of his patent, Tilghman was to be confined to the very ranges of heat above described; that it was an essential condition of the patent that there should be heat not below 510° Fahr.;*fn4 that the manipulation should be rapid, not exceeding ten minutes; that the vessel should be entirely filled with the mixture of fatty matter and water, and that no steam whatever should be permitted in it.

He contended, in addition, as the Reporter understood it, that this construction of the patent was the right one on the face of the instrument and on principles of patent law, independently of the alleged special design of the patentee in framing his specification.

The evidence as to the range of heat by which fats are destructively decomposed, seemed, as the Reporter read it, to show, perhaps, that it was one of conditions.

Renwick (see infra, 357) and Rand, experts of Mitchell, fixed the working range of Tilghman's patent at from 440° F. to 660° F.; and Rand and Wayne, also his experts, testified that the chemical action is the same with water heated and under pressure from 300°F. to 600°F.

From what has been said the reader will have perceived that the first question in the case was––

The construction of the patent. Tilghman had 'claimed' as his 'invention' 'the manufacturing of fat-acids and glycerin from fatty bodies by the action of water at a high temperature and pressure,' and he claimed as his invention nothing besides. And in the opening of his specification he declared that 'for the purpose of executing his invention, he subjected these bodies to the action of water at a high temperature and pressure,' and declared nothing more.

But he had said in his specification, that he 'mixed the fatty body to be operated on with from a third to a half of its bulk of water,' and that 'the mixture may be placed in any convenient vessel in which it can be heated to the melting-point of lead, until the operation is complete;' adding that 'the vessel must be closed and of great strength, so that the requisite amount of pressure may be applied to prevent the conversion of the water into steam.' Saying nothing, however, about keeping the vessel entirely full of the mixture.

And he had described more specially 'an' apparatus by which 'the process may be performed more rapidly, and also continuously, by causing the mixture of fatty matter and water to pass through a tube heated to the temperature already mentioned,' &c., which he said he believed to be the best mode of carrying his invention into effect, but which apparatus he stated that he 'did not intend to claim as any part of his invention.'

He had stated also that 'the melting-point of lead had been mentioned as the proper heat to be used in this operation, because it had been found to give good results; but that the change desired took place with some materials at or below the melting-point of bismuth;' and 'that no steam or air should be allowed to accumulate in the tubes, which should be kept entirely full of the mixture;' and that although decomposition took place 'with great quickness at the proper heat,' he 'preferred that the mixture, while flowing through them, should be maintained at the desired temperature for ten minutes.'

And he had said, when speaking of the matter of heat:

'By starting the apparatus at a low heat and gradually increasing it, the temperature giving products most suitable to the intended application of the fatty body employed, can be determined.'

Was, then, the invention claimed (a process) so inseparably connected with certain means, that is to say, with certain and specific degrees of high temperature, or fulness of vessels or tubes, or rapidity of manipulation, as that, unless it was effected through those same specific degrees of high temperature, or fulness of vessels or tubes, or shortness of time, it could not be effected under the patent at all?

If this question was to be answered affirmatively there was no necessity to make a single inquiry further:–there was an end of the complainant's case; though, it might be admitted, that the defendant was doing exactly that which in the claim to his patent Tilghman claimed as his invention, to wit, the 'manufacturing of fat-acids and glycerin from fatty bodies by the action of water at a high temperature and pressure.' For however practical Tilghman's exact methods and exact means might be–that is to say, however much and well reduced into use–the defendant confessedly was not using exactly the same methods, or exactly the same means, in the particulars just mentioned, but was using methods and means different, confessedly, in some details of both. Plainly, he did not infringe.

But if this first question was not to be answered affirmatively–if the patent was to be construed broadly rather than closely–if Tilghman's invention was the manufacturing of fat-acids and glycerin from fatty bodies by the action of water at a [any] high temperature, by 'any convenient' vessel, and irrespective of manipulation in a limited time, and of tubes or vessels kept constantly and entirely full of the mixture, then, of course, arose,

2d. A question whether he was an original inventor. And if he was, then would arise,

3d. A question whether he had given anywhere such 'a full, clear, and exact' description of his invention, and of the manner of making and using the same, as would enable any one skilled in the art most nearly allied to make and use the invention; a matter required by the Patent Acts*fn5 as a condition to the validity of any patent granted.

And if he had given such a description, then would arise, as one not so immediately to be answered as before,

4th. A question whether the defendant infringed the patent of Tilghman.

It will be seen*fn6 that this court in giving its judgment took the first view of the case, that is to say, construed the patent closely; so that the other questions possible to have arisen in the case did not perhaps arise, nor indeed any question but the great one of the construction of the patent.

Nevertheless, a great body of evidence was given on the assumption that the other view–that which gave to the patent the broad construction claimed for it by the patentee–was the true one, or might be taken by the court. The case was argued largely on that assumption, and the questions which would necessarily arise in that view are discussed very fully in the opinion given in the case.*fn7

Some of the evidence is, therefore, perhaps proper to be mentioned; in mentioning which the Reporter begs leave to say that the evidence was in some parts conflicting; that in his limited space he can present it much less perfectly than he could desire, and as with larger space he would not fail to endeavor to do.*fn8 He has also to say, that in some of its parts the case presented recondite matters of chemical science; matters which he confesses that he understands but little, and is perhaps unable to understand much more. If in any points, therefore, he has fallen into error, he asks for excuse from any one whom he may either mislead or fail to lead at all.

It is requisite to state that Richard Albert Tilghman, the patentee, was a citizen of Philadelphia, and brought up a practical chemist; that having, as he conceived, made the discovery that he could by the action of water at a high temperature and pressure, produce free fat-acids and solution of glycerin from fatty and oily bodies which contained glycerin as their base, he went in 1853 to England, and there, March 25th, 1854, obtained a patent from the British government for his invention. In the same year he got patents for the same invention from the governments of the United States, of France, and of Belgium; that granted by the United States being given at supra, p. 291. He was in Europe and America alternately, from 1853 to 1859; and returned to the United States in August or September of the year last named.




The fact that Tilghman was the person who first distinctly observed and publicly announced that water, in a liquid state, at a high temperature and under pressure, would, of itself, and without the aid of chemical substances, separate natural fat into its constituents of fat-acids and glycerin, did not, as the Reporter read the proofs, seem to be open to well-founded question.

Tilghman relied on the following evidence:


Among these the following were specially quoted:

1. Richardson & Watts's Chemistry Applied to the Arts, London, 1863,*fn9 where it is thus said:

'The only perfectly unobjectionable mode of obtaining glycerin, inasmuch as it alone insures the entire absence of mineral impurities, is the decomposition of the fats by the vapor of water at a high temperature. This mode of decomposition was first adopted as a means of obtaining fatty acids and glycerin by Mr. Tilghman, in 1854.'

2. Musprat's Chemistry, London, 1856-8, article 'Glycerin,'*fn10 where it is thus said:

'A much more economical method is that introduced by Mr. Tilghman in 1854. By this process the fatty bodies are broken up into acid and basic substances, through the agency of heat, pressure, and steam.'

3. Watts's Dictionary of Chemistry, London, 1864,*fn11 article 'Glycerin,' where it is thus said:

'By heating fats with water or with steam. This is the only unobjectionable method of obtaining glycerin, inasmuch as it alone insures the entire absence of mineral impurities. It was first carried out by Mr. Tilghman in the following manner.'

Tilghman's mode of working with the coil apparatus is then described.


1. The Paris jury of savants, at the Exposition of 1855, when speaking of Chevreul, the eminent French chemist, say:

'We can affirm, without fear of contradiction, that, with the exception of the undertaking of the saponification of the fatty bodies by water, which remained unknown to him, he has indicated in a clear and precise manner all the scientific bases upon which depend the different methods of practical manufacture of the fatacids employed for making candles.'

And speaking of Tilghman, under the head of 'Aqueous saponification in a close vessel,' the same jury say:

'It was Mr. Richard Albert Tilghman, chemist, of Philadelphia, who was the first who had the idea of applying this reaction on a large scale. In his patent taken in London, the 25th of March, 1854, he thus sets forth his discovery, and his manner of operating:

"My invention consists in a new method of obtaining free fat-acids and solution of glycerin from animal and vegetable fatty and oily bodies which have glycerin as their base.

"My invention consists in exposing the aforesaid fats and oils to the action of water at a high temperature and pressure, the effect of which is to cause the combination of the water with the elements of the neutral fats, so as to produce at the same time free fat-acids and solution of glycerin."

2. Professor J. C. Booth, analytical chemist, of Philadelphia, called and recalled, was thus in substance interrogated, and thus in substance answered:

'Q. With whom did you study chemistry, and where? How long have you been engaged in the profession of analytical chemist? What posts, if any, in public institutions have you held, and what works or papers have you written on chemistry?

'A. I studied chemistry with W ohler, in Cassel, Germany, and with Professor Magnus, in Berlin, during 1833, 1934, and 1835. From 1835 to the present time I have been engaged as professional analytical chemist. I was professor of Chemistry applied to the Arts in the Franklin Institute, Philadelphia, for ten years; and Professor of Chemistry and Physics in the Central High School, Philadelphia; I have been for the last eighteen years in the United States Mint, and I still continue, independent of the mint, my profession of analytical chemist. I am the author of the greater part of the Encyclopedia of Chemistry; of a report upon the progress of chemical manufactures made to the Smithsonian Institute, at the request of the perpetual secretary of that institute, Professor Henry; I also edited the translation of Regnault's Chemistry, translating much of it myself, and annotating it.

'Q. From your knowledge of chemistry, who would you say was the discover of the chemical power of water in a liquid state, at a high temperature and pressure, on fats, to produce fatacids and glycerin?

'A. Mr. R. A. Tilghman.

'Q. Do you know of any other person who has claimed the merit of this discovery?

'A. I know of no other.

'Q. Is this discovery regarded as a new and important fact in chemistry?

'A. It is so regarded.'

3. The answer of the defendant having set up that it was shown by a paper published in the year 1823 (Journal of Science, London, vol. xvi, p. 172), entitled, 'Change of Fat in Perkins's Engine by Water, Heat, and Pressure,' that Tilghman had been anticipated in his discovery, and, as will be hereafter seen, some reliance having been placed on that paper, the examination of the witness thus proceeded:

'Q. Give a list of chemical treatises that you have examined on the subject of this discovery and its date, and particularly with a view of showing whether it was known between 1823 and 1854, and whether it has been known since 1854.

'A. I annex a list of standard chemical treatises, of the highest authority, of dates between 1823 and 1854, which I have examined. They all contain descriptions of the properties of fat and fat-acids, and the known methods of producing fat-acids and glycerin. None of them mention the fact that fat-acid and glycerin can be produced by the action of water on fats at a high temperature and pressure.

'I annex another list of standard chemical treatises of dates subsequent to April 3d, 1854, all of which contain mention of that chemical fact.

'I therefore infer and conclude that that chemical fact was first made known subsequent to 1852, an prior to April 3d, 1854.

List of treatises published between 1823 and 1854, which do not mention the chemical fact.

Dumas's Chemistry, vol. 5. Paris, 1835.

Berzelius's Chemistry, vol. 2. Brussels, 1838.

Ure's Dictionary of Chemistry. London, 1831.

Brande's Chemistry. London, 1841.

Graham's Chemistry. London and Philadelphia, 1843.

Booth's Encyclopedia of Chemistry. Philadelphia, 1850.

Regnault's Chemistry. Paris and Philadelphia, 1852.

Gerhardt's Chemistry. Paris, 1854.

Gmelin's Chemistry, vol. 7. London, 1852.

Pelouze & Fremy. Chemistry. Paris, 1850.

List of chemical treatises published after April 3d, 1854, which do mention that chemical fact.

Comtes Rendues. Paris, April 3d, 1854.

Liebig & Kopp's Year-book. Giessen, 1855.

Miller's Chemistry. London, 1862.

Watts's Dictionary of Chemistry. London, 1864.

Gmelin's Chemistry, vol. 16. London, 1864.

Musprat's Dictionary of Chemistry, vol. 2. London, about 1856-8.

Chemical Gazette. London, 1856.

'Q. State what technical works on the subject of the manufacture of fat-acid, published between 1823 and 1854, you have examined, and whether any of them contains any description or notice of the process of manufacturing fat-acid and glycerin from fats by the action of water at a high temperature and pressure.

'A. I have examined the following technical works, all of which contain descriptions of the various processes for the manufacture of fat-acids. None of them mentions or refers to the process for the manufacture of fat-acid and glycerin by the action of water on fats at a high temperature and pressure.

Chevreul & Gay-Lussac's Patent. Paris, 1825.

Hibert's Encyclopedia. London, 1838.

Dumas's Chemistry, vol. 6. Paris, 1863.

Parnell's Applied Chemistry, vol. 2. Landon, 1844.

Knapp's Technology. London and Philadelphia, 1848.

Roret's Encycolopedia. Fat-Acids. Paris, 1849.

Morfit's Chemistry of Soap and Candles, 1st edition. Philadelphia.

Payen's Chemistry. Paris, 1851.

Official Report of London Exhibition. London, 1851.

Tomlinson's Cyclopedia of Arts. London, 1852.

Appleton's Dictionary. New York, 1852.

Ure's Dictionary of Arts. Boston, 1853.

'Q. State what technical works on the subject, published since 1854, you have examined, and whether they mention the process of manufacturing fat-acids and glycerin by the action of water on fat at a high temperature and pressure, and to whom they refer as the inventory of that process.

'A. I have examined the following technical works. They all mention the water process, and refer to Tilghman as its inventor:

Bulletin de la Soci et e d'Encouragement. Paris, 1855.

Morfit's Chemistry of Soap and Candles, 2d edition. London and Philadelphia, 1856.

Official Report of London Exhibition. London, 1863.

Richardson & Watts's Technology, vol. 1, part 3. London, 1863.

Repertory of Patent Inventions, 3d series, vol. 24, page 408. London, 1854.

Mechanics' Magazine, vol. 61, page 111. London, 1854.

Newton's Journal of the Arts and Sciences, vol. 45. London, 1854.

Franklin Institute Journal, 3d series, vol. 29, page 36. Philadelphia, 1855.

'Q. Please state in general terms the result of your examination of the standard chemical and technical publications.

'A. No one of the technical treatises or chemical works, published prior to 1854, contains any mention either of the chemical fact of the decomposition of fat by water at a high temperature and pressure, or of the manufacturing process founded upon it. After 1854 both the chemical fact and the manusacturing process are mentioned in numerous technical and chemical publications.'

The testimony of––

4. Professor R. E. Rogers, Professor of Chemistry for ten years in the University of Virginia; Professor of the same science for eighteen years in the University of Pennsylvania; editor of the last American edition of Turner's Chemistry,

5. Professor Wolcott Gibbs, who had studied with Professor Hare, of Philadelphia; with Dr. Torrey, of New York; with Professors Ramelsberg and Rose in Berlin, Prussia, and with Liebig in Giessen; for ten years Professor of Chemistry and Physics in the Free Academy in New York, and now Rumford Professor in Harvard University,

6. Professour F. A. Genth, student for two years with Professor Gmelin; for two with Liebig and others; for three years assistant to Bunsen; for two years Professor in the University of Marburg,

7. Professor Robert Bridges, Professor of Chemistry in the Philadelphia College of Pharmacy; editor of Graham's Chemistry, and of several editions of Fowne's Chemistry,–all sustained the assertion of Professor Booth as to the originality of Tilghman with the invention.

Professor Gibbs thus testified:

'Q. State when and by whom your attention was first called to the question of the novelty of the plaintiff's patented invention, as affected by defendant's exhibits. State whether you then made a full investigation of the subject, and a report, and state the substance of any such report.

'A. My attention thereto was first called by Mr. Mitchell, the defendant, in the early part of the year 1863. I then made a full investigation of the subject at his request, and gave him a written opinion, the substance of which was that the plaintiff's invention was new.'

8. The testimony of the Patent Office. In 1858, Mr. Werk, a manufacturer of candles in Cincinnati, and afterwards sued by Tilghman as an infringer of his patent, applied to the Patent Office for an improved treatment of fatty acids through the aqueous process. He was thus replied to by the Honorable Joseph Holt, then Commissioner of Patents:


'June 26th, 1858.

'SIR: Your application for a patent for an improved treatment of fatty acids has been examined. You are referred to Reganault's Chemistry, vol. ii, p. 1594; to Payen's Chemie Industrielle, p. 771, and to the patents of R. A. Tilghman, January, 1855, and October, 1854. Mr. T. is the acknowledged discoverer of this process. The application is refused for want of novelty.

'Respectfully yours, &c.,

'J. HOLT, Commissioner.


9. The London International Exhibition of 1862. At this exhibition one of the juries, reporting on the subject of oils, fats, wax, and their products, and referring to the efforts made 'as early as 1855,' by M. De Milly, to modify the process of saponification by means of lime, said:

'Instead of effecting this decomposition at a temperature of 212°, and employing 14 per cent. of lime, he raised the temperature by working under pressure and employing only 4 per cent. of lime.

'At the present time M. De Milly has, indeed, reduced the proportion of lime to 21 1/2 per cent. This process has been imitated in Austria. Undoubtedly it constitutes a real improvement upon the ordinary method of saponification by lime; but in spite of this considerable improvement, which is in fact but a combination of Mr. Tilghman's mode of saponification by water at a high temperature,*fn12 combined with the lime process, we cannot believe that these two methods of saponification, under any modification at present attempted, can, in an economical point of view, successfully compete with the sulphuric saponification.'
10. Medal of Honor. The report of the same exhibition*fn13 contains this:


'UNITED STATES: TILGHMAN, for fatty acids obtained by aqueous saponification.'


1. Mr. G. F. Wilson, manging agent of Price & Co.'s Patent Candle Company, at Battersea, London–the largest candle factory in the world–who, it appeared, was besides a man of education and had made the general and particular matters now under consideration the subject of learned research, and was in the habit of writing and lecturing upon them, affirmed that Tilghman was the discoverer of the invention claimed by him. In a public lecture, delivered by him in January, 1856, before the Society of Arts, in London, he said:

'In January, 1854, Mr. Tilghman, an American chemist, who has studied all that has been published here and in France on the subject of acidification and distillation of fatty bodies, obtained a patent for exposing fats and oils to the action of water at a high temperature, and under great pressure, in order to cause the combination of the water with the elements of the neutral fats, so as to produce at the same time free fat-acids and solution of glycerin. He proposed to effect this by pumping a mixture of fat and water, by means of a force-pump, through a coil of pipe heated to about 612° Fahr., kept under a pressure of about 2000 pounds to the square inch; and he states that the vessel must be closed so that the requisite amount of pressure may be applied by prevent the conversion of water into steam. This is, all must admit, a beautiful, original chemical idea, well carried out.'

The defendant, Mr. R. G. Mitchell, who was a witness, testified that the process by water, heat, and pressure alone had not been known to him before the date of Tilghman's patent, nor indeed known to him until four years afterwards. He said:

'I have known for more than forty, years that fats were acidified by moisture. I never knew that fat-acids and glycerin could be obtained from fats by heat, water, and pressure until I heard of it in connection with the patent of Wright & Fouch e, in 1859.'




No scientific treatise was produced which denied, with mention of Tilghman's name, or by specific reference to what he asserted to be his, that he had discovered what in the claim to his patent he claimed as his invention. An extract from a paper in the Journal of Sciences, vol. xvi, p. 172, published in London in 1823, entitled, 'Change of Fat in Perkins's Engine by Water, Heat, and Pressure,' and made by the defendant an Exhibit (E) in the case, and somewhat relied on by him, mentioned that

'Mr. Perkins used in his steam-cylinder a mixture of about equal parts of Russia tallow and olive oil to lubricate the piston and diminish friction; that the mixture was consequently exposed to the action of steam at considerable pressure and temperature; and, being carried on by steam, it was found in the water, giving rise to peculiar appearances.'

A particular account, too long to be here inserted, was annexed.


1. Professor P. H. Vanderweyde, a native of Holland, educated in chemistry at the Royal University of Delft, M.D., Professor of Chemistry in the New York Medical College, and in the Cooper Institute, and fifteen years in America, was at different times asked and answered thus:

'Q. From your knowledge of chemistry, would you say that complainant was the discoverer of the power of water under heat and pressure to dissolve fats into acids and glycerin?

'A. The more my information about the matter has increased the more I am convinced that the power of water to decompose fats into the fatty acids and glycerin was known a long time before the date of Mr. Tilghman's patent.

'Q. Do you know, or did you ever hear of any standard chemical treatise or book, which states that complainant made any chemical discovery as to the decomposition of fats into fat-acids and glycerin?

'A. I do not know, nor did I ever hear of such a statement; and, in those standard works, when Mr. Tilghman's process is mentioned at all, it is stated simply that he took out a patent for a certain apparatus.'


'Q. State who was the first person, within your knowledge, who made the explicit statement that fat-acids and solution of glycerin could be obtained for manufacturing purposes by the action of liquid water on neutral fatty bodies at temperatures above 350° Fahrenheit; and state when and where such statement was made.

'A. I am not aware that any other man made that precise statement, with all the special conditions mentioned in the question, before Mr. Tilghman.

'Q. Who was the first person who got so far as to use 'water alone' in the practical manufacture of stearic and margaric acid, and oleic acid, and glycerin, from neutral fat?

'A. I know not who the first person was who practically manufactured stearic and the other fatty acids besides glycerin, from the fats by means of water alone; but I know that Mr. Tilghman took a patent for that purpose. I doubt, however, if it was ever put in practical operation. Surely not to make glycerin.'

2. The defendant having put in evidence an extract from the Journal of Science, London, 1823, vol. xvi, p. 172, entitled 'Change of Fat in Perkins's Engine, by Water, Heat, and Pressure,' which paper was marked 'Exhibit E' (quoted supra, p. 314)––

Florence Verdin, partner of the defendant, under the firm name of Mitchell & Co., and who testified that he had an interest against the patent, and if in the present suit a sum of money was decreed to be paid to the complainant, he would be, he supposed, responsible for one-half, had testified, in 1868, in another case (all the testimony in which was received by consent), as follows:

'Q. Would not any manufacturer of ordinary skill and information in his art, as current prior to 1854, have known from Exhibit E that fat-acids and glycerin were produced by the action of water at a high temperature and pressure, and does not the presence of acrolein involve the production of glycerin?

'A. I should have known it, and I cannot doubt others would, as a person had only to subject the fat to the action of water at a temperature and pressure named to have acidified fats; acrolein cannot be formed without glycerin being formed first.

'Q. Do you know of any standard chemical treatise or book which states that the complainant has made any chemical discovery in reference to the decomposition of fats into fat-acids and glycerin?

'A. I do not know of any such works which give Tilghman the credit of being a chemical discoverer.

'Q. Did you ever hear of any standard chemical treatise or book which ascribes to the complainant any such discovery?

'A. I have never heard of any.

'Q. Are technical works of any value to the manufacturers of fat-acids and candles, so far as you have examined them, and if so, what?

'A. They have never been to me; my knowledge was always superior to theirs; they are generally more likely to mislead the manufacturers than to benefit them.

'Q. Is the information communicated in Tilghman's patent of 1854 of any more value to a manufacturer of fat-acids and candles than that which is found in defendant's Exhibit E?

'A. I think there is no difference between the two, and I have always thought, and think so yet, that the patent of Mr. Tilghman had been copied from Exhibit E.'


'Q. When did you first see it stated in a book or document that highly heated water under pressure would, without the aid of chemicals, decompose neutral fat into fat-acid and a solution of glycerin?

'A. I don't know when.

'Q. Can you swear you ever saw that statement prior to the date of Mr. Tilghman's patent, January, 1854?

'A. I cannot.'

3. See also testimony of Drs. Rand and Wayne, ...

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