Mitchell v. Tilghman
86 U.S. 287

Annotate this Case

U.S. Supreme Court

Mitchell v. Tilghman, 86 U.S. 19 Wall. 287 287 (1873)

Mitchell v. Tilghman

86 U.S. (19 Wall.) 287




What R. A. Tilghman, of Philadelphia, claimed as his invention under the letters patent granted to him of January 9, 1854, was the process of manufacturing fat acids and glycerin from fatty or oily substances by the action of water at a high temperature and pressure.

Two conditions, viz., that the heating vessel must be kept entirely full of the mixture of fat and water and that no steam or air must be allowed to accumulate in the vessel employed to impart the heat, were material and indispensable conditions of Tilghman's patented method.

The claim of the patentee must be limited to the specific method or means of applying highly heated water under pressure pointed out in the specification; and although the claim is on its face broader than this, yet it is to be construed by reference to the specification.

In this point of view, it is unimportant whether the claim contained any direct reference to the specification or not. Such reference, where not expressed, will be implied.

The precise apparatus described in Tilghman's specification does not appear to have gone into practical use in this country or in Europe, and the apparatus worked by Tilghman's licensees differs in many material respects from the apparatus described in his patent, and, taken as a whole, therefore, it was considered by this Court that Tilghman did not succeed in introducing his invention into practical use by the means and mode of operation described in his specification.

Accordingly, where a defendant had used highly heated water in a close vessel, but used a much more moderate degree of heat than specified by Tilghman, and used an entirely different apparatus from Tilghman's, and one which permitted the existence of steam as well as water -- construing Tilghman's claim of invention as limited by the specific means and mode of operation described in his specification -- such defendant was held not to have infringed.

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,

Page 86 U. S. 288

October 3, 1854, for fourteen years from January 9, 1854, the reduction of the patented improvement to use, and the infringement 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 constituents, 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

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