MR. JUSTICE HOLMES delivered the opinion of the Court.
This is a suit for the infringement of Letters Patent, No. 962678, Claims 1 and 2, brought by the petitioner in the District Court of Maine, where the petitioner prevailed, 23 F.2d 931, the Court acting partly in deference to the decision of the Circuit Court of Appeals for the Third Circuit in Miami Copper Co. v. Minerals Separation, Ltd., 244 Fed. 752. The decision of the District Court was reversed by the Circuit Court of Appeals for the First Circuit, 30 F.2d 67, and because of the conflict with the Third Circuit, a writ of certiorari was granted by this Court.
The claims are (1) for a "process of concentrating ores which consists in mixing the powdered ore with water containing in solution a small quantity of a mineral frothing agent, agitating the mixture to form a froth and separating the froth," and (2) the same as (1) except that it inserts the word `organic' before `mineral frothing agent.' The only defence that it is necessary to consider is that the disclosure is anticipated by the earlier patent, No. 835120, which has been before this Court in Minerals Separation, Ltd., v. Hyde, 242 U.S. 261, and Minerals Separation, Ltd., v. Butte & Superior Mining Co., 250 U.S. 336. It is enough to refer to those cases without repeating them. The process described in 835120 "consists in mixing the powdered ore with water, adding a small proportion of an oily liquid having a preferential affinity for metalliferous matter, (amounting to a fraction of one per cent. on the ore), agitating the mixture until the oil coated mineral matter forms into a froth, and separating the froth from the remainder by flotation." The specification describes the object as being to separate metalliferous matter, &c., from gangue by means of oils,
The petitioner, admitting that both patents are for processes, says that they are fundamentally different in their respective principles of action; that in the present patent, 962678, the mineral frothing agent is dissolved in the water and produces the metal-bearing bubbles, no one knows exactly how, by modifying the water; whereas in the earlier, 835120, oil is used which does not dissolve in the water but coats the particles of metal with a thin coating of oil, which it could not do if it were soluble, and thus shows its preferential affinity when shaken up with the metal pulp.
The question is not what is the precise scope of the claims in 835120, but what is disclosed in the specification and made known to the world. Alexander Milburn Co. v. Davis-Bournonville Co., 270 U.S. 390. Therefore we are relieved of the inquiry whether the words `oily liquid' in Claim (1) can be read as a shorthand expression for the previously mentioned oils `and other substances which have a preferential affinity for metalliferous matter over gangue,' as `oil' was expressly interpreted in earlier patents, including one to Cattermole referred to at some length in 835120, and as there is evidence that it thus was understood by men skilled in the art. It is disclosed that it was well known there were other substances besides oil that had the preferential affinity and
The discovery was that a very minute portion of the oil worked in an unexpectedly different way from that familiar with larger quantities — not in the matter of coating the particles, but in helping to produce a froth that floated instead of granules that sank, and thus in preserving the slime made by the smaller particles with the water, and so saving a large proportion of metal that
The petitioner adverts to the success that has attended the later patent and to the fact that the world waited until it appeared. But interlopers naturally would be slow to venture into the field occupied by a powerful company armed with patent No. 835120 and supported by a subtle ingenuity that we cannot doubt would have been exercised with even more effect to show that a process like that in No. 962678 was an infringement than it now is to prove that the later patent was a revelation that transformed the art.