This suit was brought for the alleged infringement of certain letters patent, No. 607,719, and issued July 19, 1898, for an alleged invention, by one Waldstein, for “certain new and useful improvements in processes for the recovery of precious metals from their solutions.” The relief sought was an injunction, an accounting, and damages. Among the defenses set up by the answer of the defendant were lack of novelty and invention, anticipation, no infringement, and a wánt of sufficient description of the alleged invention. The court below held the patent void, and the case is brought hereby the plaintiff.

*241 The invention claimed being only for improvements in well-known processes, and in no sense one of a pioneer character, the patentee must be held to a strict construction of his claims. Wright v. Yuengling, 155 U. S. 47 , 15 Sup. Ct. 1, 39 L. Ed. 64 ; Westinghouse v. Power-Brake Co., 170 U. S. 562 , 18 Sup. Ct. 707, 42 L. Ed. 1136 .

The specification and claims of the patent are as follows:

It is thus seen that what is first claimed by the appellant is zinc dust in a state of agitation; second, a definite quantity of zinc dust in a state of agitation, sufficient only in quantity to thoroughly precipitate the contained metals; and, by the third claim, the process for extracting and recovering precious metals from their ores, consisting of certain specified steps, the first and fourth of which are beyond all question old, and the second and third of which steps consist in supplying to the solution charged with the precious metals the exact quantity of zinc dust ascertained (without telling how) to be sufficient to precipitate the said metals, and agitating the solution and zinc dust until such metals are precipitated, and the dust absorbed. The record shows that in an affidavit filed in the patent office by Waldstein, November 30, 1897, in support of his application for a patent, it is stated that he made his discovery “on or about the 15th day of July, and not later than the 15th day of August, 1894.” It is not pretended that he discovered zinc dust. And although we find in the specification the words, “I do not claim pulverized or mechanically divided zinc; I only claim zinc dust,” the very next clause of the specification itself shows, what other portions of the record abundantly establish, that zinc dust, or zinc fumes, as it is also called, had long been a well-known article of commerce, being a product resulting from the cooling of zinc while in a state of vapor. Indeed, in the brief of counsel for the appellant is the express declaration: “We do not pretend that Waldstein invented or discovered zinc dust, nor do we claim that he invented the atomic weight theory, or that he invented agitation. This fallacy permeates the argument against the patent throughout.” It may be added with equal truth that he did not invent the theretofore well-known cyanide solution, consisting of an aqueous solution of cyanide of potassium, with which pulverized ores are, and for many years before Wald stein’s time had been, treated for the purpose of extracting the metals therefrom. The record shows that the use of zinc in various forms, for precipitating copper and the precious metals from cyanide solutions, was well known in the art long before Waldstein’s alleged discovery. As early as April 21, 1866, the Scientific American, of New York, being .asked how to recover gold from a plating solution which was spoiled by adding, direct, a nitro-muriate solution of gold to the common cyanide solution, published the following answer:

*243 “The bath is probably not injured. To recover the gold, put stick of bright zinc into the solution. Zinc will precipitate gold from any solution.”

The Paraf-Javal patent, issued in France, July 31, 1866, No. 72,466, shows that zinc was not only then known and used in the art of precipitating metals, but that form of it known as zinc dust, and that, the finer the metal used as the precipitant, the better the result. In the description in that patent, which was for “improved chemical processes,” it is said:

In the Paraf English patent of August 1, 1866, for “improvements in deoxidation and precipitation,” it is said:

An English patent, No. 10,223, and issued July 14, 1888, to MacArthur and Forrest, for “improvements in extracting gold and silver from ores or other compounds,” sets out their method of treating a cyanide solution containing gold and silver by causing it to pass through a mass of metallic zinc in a state of fine division. In the patent issued by the United States to MacArthur and Forrest December 24, 1889, and numbered 418,137, for a “process for separating gold and silver from ore,” in which the cyanide process is used as the separating agent, it is said:

In an article published in the Engineering and Mining Journal, of New York, on the 6th day of August, 1892, it was said, in referring to the MacArthur-Forrest patents:

*244 In an article entitled “Mixed Metals or Metallic Alloys,” by Arthur H. Hiorns, the date of which publication does not appear from the record, but is said in one of the briefs to have been in 1890, reference is made to the fact that zinc displaces gold, silver, and other metals from their solution; and it is said that “in the form of fine dust it is obtained in large quantities, mixed with zinc oxide, and forms a valuable reducing agent.” Not only was zinc dust here, and in some of the previous references, distinctly suggested as a precipitant of the precious metals from their solutions, but throughout the testimony on both sides of this case it is shown that in such precipitation the chemical action is purely a surface one, and, therefore, it required but the exercise of ordinary common sense to know that, the larger the surface oí the precipitant, the quicker and more effective must be the precipitation. This fact is distinctly admitted by Waldstein himself, in his deposition, where he says:

D. K. Tuttle, a witness called by the appellant, and at the time of giving his deposition a melter and refiner in the mint of the United States at Philadelphia, having stated that zinc turnings were usually employed in the precipitation of the precious metals from cyanide solutions, and being asked' why the turnings were used instead of sheet zinc, answered:

This witness, being questioned in regard to his metallurgical experiences, further testified as follows:

Zinc dust, it is shown, is composed almost entirely of metallic zinc and zinc oxide. Whether the oxide causes the formation of an electric or voltaic couple in the solution, thereby facilitating precipitation, as contended on behalf of the appellant, or retards it, as claimed for the appellee, we regard as unimportant. The fact remains, as is very clearly shown by the foregoing references, and by others appearing in the record, that at the time of, and for many years prior to, Wald stein’s alleged discovery, zinc dust was well known, not only as a precipitant of the precious metals from a cyanide solution, but that it was regarded, by some at least, as the best form in which zinc could be used for that purpose. Neither the article itself, nor its precipitating character, could, therefore, have been discovered by Waldstein in 1894. And the record shows that it was just as well known at that time that agitation of the solution during the application of the dust would expedite and facilitate the precipitation of the metals.

In Presenius’ Chemical Analysis, published in 1850, it is said:

In Kustel’s treatise on Roasting of Gold and Silver Ores, published in 1880, it is said:

And referring to the precipitation of gold in the chlorination process, the same author says:

In the Metallurgy of Silver, Gold, and Mercury, published in 1887 by Thomas Pgleston, he refers to the use of a paddle to stir the solution by hand, but says:

In an article published in the Industrie-Blatter, at Berlin, Germany, August 23, 1890, we find the following:

In an article published in the Berg-Und-Huettennmaenische Zeitung, at Leipsic, Germany, October 17, 1890, it is said:

In the chemical magazine called “Chemiker-Zeitung,” published at Cothen, Germany, October 29, 1892, the publisher said:

An English patent, No. 5,152, was issued October 29, 1883, to Astley Paston Price, for “improvements in the extraction of the precious metals from their ores, and from metallurgical compounds or products containing the same,” in which his claim was as follows:

Within a month thereafter, to wit, November 16, 1883, the United States issued to Price a patent for “improvements in obtaining copper from cupreous solutions,” in which the specification states, among other things, that the invention consists “in effecting the precipitation of the copper from its solution or solutions by the employment of zinc when in a state of fine division, such, for example, as that which is known as ‘zinc fume’ or the ‘condensed vapor of zinc.’ ” In his specification, Price there further said:

It is perfectly plain that the process here described, of using zinc dust or fume with mechanical agitation for the precipitation of copper, is the identical process stated in the first claim of the Waldstein patent for precipitating gold and silver. The latter was nothing more than the application of that old process to analogous matter, producing a result substantially similar in its nature, and was therefore entirely lacking in invention. Ansonia Brass & Copper Co. v. Electrical Sup *247 ply Co., 144 U. S. 11 , 12 Sup. Ct. 601, 36 L. Ed. 327 ; Manufacturing Co. v. Cary, 147 U. S. 623, 637 , 13 Sup. Ct. 472, 37 L. Ed. 307 .

It is contended on the part of the appellant that the quantity of such dust to be so used is covered by claims 2 and 3 of the Waldstein patent. Claim 2, as has been seen, is for a definite quantity of zinc dust in a state of agitation, sufficient only in quantity to thoroughly precipitate the contained metals, and claim 3 is for the exact quantity of zinc dust ascertained to be sufficient to precipitate the said metals, agitating the solution and zinc dust until such metals are precipitated and the dust absorbed. Ascertained how? No proportions are given, and, indeed, not a word is said in the patent from which any one desiring to use the process described therein can determine the “definite .quantity” referred to in the second, or the “exact quantity” referred to in the third, claim of the patent in question. In the absence of specific information upon the subject, the desired quantity can, in the nature of things, only be determined by experiment.

Section 4888 of the Revised Statutes provides:

See, also, Mitchell v. Tilghman, 19 Wall. 287, 394 , 22 L. Ed. 125; Béné v. Jeantet, 129 U. S. 683 , 9 Sup. Ct. 428, 32 L. Ed. 803 ; Howard v. Stove Works, 150 U. S. 164, 167 , 14 Sup. Ct. 68, 37 L. Ed. 1039 ; Schneider v. Lovell (C. C.) 10 Fed. 666; Welling v. Crane (C. C.) 14 Fed. 571 ; Eockwood v. Faber (C. C.) 27 Fed. 63 ; Chemical Rubber Co. v. Raymond Rubber Co., 18 C. C. A. 31 , 71 Fed. 179 .

We are unable to see any invention in anything disclosed by the Waldstein patent, and must therefore affirm the judgment of the court below. The real inventor is undoubtedly to be encouraged, and the courts should always be careful to protect his rights; but it was never the intention of the patent law to give a monopoly to a mere follower of the knowledge and ingenuity of others. The judgment is affirmed.

with whom concurred MORROW, Circuit Judge. While concurring with the conclusion that the decree of the circuit court should be affirmed, and agreeing with that part of the opinion which holds that claim X of the patent of appellant is for an old process applied to a new use, we are unable to assent to the conclusion that claims 2 and 3 are fatally defective for the reason that no proportions are given, and nothing is said in the patent from which one desiring to use the process can determine the “definite quantity,” or the “exact quantity,” referred to in those claims. We are not prepared to say that, in a patent for a process such as described in the appellant’s claims, the inventor might not be protected in the use of his process if, from the very nature thereof, it would be impossible to state in his claims the precise quantity of material necessary to accomplish the desired result. From the nature of the appellant’s process, and the varying conditions under which it must necessarily be applied in practical mining, it is apparent that the appellant, if he were the inventor of a new and useful method of applying zinc dust to a precipitation of precious metals from cyanide solution, could publish no definite formula for his process. The best that he could say would be that his process required the use of such a quantity as, from experiment or analysis of varying ores, would be found in each case to be the requisite amount for complete precipitation. We think, as did the court below, that,' to one skilled in the art to which the patent refers, the information afforded by the claims w.ould be sufficient. But we think that the nature of claims 2 and 3 is such as to be incapable of protection by patent. The appellant was not the inventor of the use of zinc dust, by means of agitation, for the purpose described in his claims. That use being already known in the art, his patent is left to rest upon his claim of the use of a definite quantity. This claim, we think, cannot be made the subject of patent. Conceding that the appellee and others had the right to use zinc dust, and to use it by means of agitation, it must follow that they would have the right to use such quantity as would best accomplish the result desired. The appellant cannot take from them that right, or the right to experiment, and adjust the quantity of material, by asserting that he is the first discoverer of the use of a definite quantity, or the exact quantity, *249 which will precipitate all the mineral in the solution. If all the claims of his patent are good, it follows that others can only avoid infringement by using zinc dust in an unskillful way, by either using too much or too little. The right to use the dust being free to all, we think it follows, necessarily, that all have the right to adjust the quantity of the material to the necessities of each case, and to ascertain by experiment or analysis, if need be, the quantity that may be required to produce the desired end, and that such a use cannot be made the subject of monopoly, there being involved in it no discovery, but only the exercise of ordinary prudence and skill.