Minerals Separation, Ltd. v. Butte & Superior Mining Co.,
250 U.S. 336 (1919)

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U.S. Supreme Court

Minerals Separation, Ltd. v. Butte & Superior Mining Co., 250 U.S. 336 (1919)

Minerals Separation, Limited v. Butte & Superior Mining Company

No. 599

Argued March 19, 1919

Decided June 2, 1919

250 U.S. 336


Patent No. 835,120, for improvements in the process of concentrating ores, by means of oils, etc., sustained as to Claims Nos. 1, 2, 3, 4 and 12. P. 250 U. S. 339. Minerals Separation, Ltd. v. Hyde, 242 U. S. 261, approved.

These claims, as now and heretofore upheld by this Court, cover the use in the process of the oils of the patent in amounts equal to any fraction of one percent on the ore. P. 250 U. S. 341.

The oils contemplated by the patent include not only pine oil and other oils referred to in the testimony, but not in the patent, as "frothing oils," but also the petroleum products kerosene and fuel oil, which, though less efficient, are useful in the patented process. P. 250 U. S. 344.

Page 250 U. S. 337

Therefore, the use in the process of a combination of pine oil, kerosene, and fuel oil in an aggregate amount exceeding the maximum percentage of oil fixed by the claims, supra, does not infringe the patent, even though the pine oil used is less than that percentage and would have produced more efficient results if used alone. P. 250 U. S. 345.

In respect of the oils to be employed, the patent discloses that, when those having "a preferential affinity for metalliferous matter" are used, in quantities amounting to a fraction of one percent on the ore, in the manner prescribed, including agitation of the mixture of oil, water and ore, there will be produced a metal-bearing froth, the result of the process; a preliminary test is stated to be necessary to determine "which oily substance yields the proportion of froth or scum desired," but no specific distinction is made among oils of the requisite "preferential affinity," and it is not "particularly pointed out" in the claims that some may be more useful than others, that some may be successfully used and some not, or that some are "frothing oils" and some are not. Held that to confine the patent by construction to the oils which will in practice produce the desired froth would subordinate the clear description of the claims to an implied and vague description which would leave the whole subject at large to become a field for further experiment, and might cause the claims to fall short of satisfying the patent law. P. 250 U. S. 349.

When an inventor comes late into a field already well developed and approaching more and more nearly to the results achieved by his invention, the patent should be construed strictly but fairly, so a to allow all, and no more than, the benefit of the discovery which it discloses to the public. P. 250 U. S. 345.

The invention must be particularly pointed out and distinctly claimed; the patent cannot be extended beyond the claims or construed in a manner different from the plain import of their terms. P. 250 U. S. 347.

The result of a process (in this case, the metal-bearing froth) is not patentable, but only the means disclosed for achieving it. P. 250 U. S. 349.

Evidence that respondent's process was inefficient and wasteful as compared with that of petitioner's patent is pertinent to the question of infringement. P. 250 U. S. 353.

A disclaimer, filed under Rev.Stats., §§ 4917, 4922 held not evasive, and, in view of the foreign residence of the patent owners and the difficulty of communication during the War, not "unreasonably neglected or delayed." P. 250 U. S. 354.

250 F. 241 reversed in part and affirmed in part.

The case is stated in the opinion.

Page 250 U. S. 338

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