General Chemical Co. v. Aluminum Co.

• Decision Date: 07 October 1924
• Docket Number: No. 536.,536.
• Citation: 11 F.2d 810
• Parties: GENERAL CHEMICAL CO. v. ALUMINUM CO. OF AMERICA.
• Court: U.S. District Court — Western District of Pennsylvania

11 F.2d 810 (1924)

GENERAL CHEMICAL CO. v. ALUMINUM CO. OF AMERICA.

No. 536.

District Court, W. D. Pennsylvania.

October, 7, 1924.

Briesen & Schrenk, of New York City, for plaintiff.

Cooper, Kerr & Dunham, of New York City, for defendant.

SCHOONMAKER, District Judge.

This is a patent suit, charging infringement of plaintiff's patent No. 1,150,415, issued August 17, 1915, to the plaintiff as assignee of the inventor, H. B. Bishop, upon application filed August 8, 1911, for improvements in the manufacture of hydrofluoric acid. The plaintiff also asserts that the defendant is the owner of two patents taken out by Mr. Fickes, Nos. 1,288,400 and 1,316,569, which patents the plaintiff alleges interfere with the plaintiff's patent. For that reason, the plaintiff, in its bill of complaint in this case, has asked proper relief under section 4918 of the Revised Statutes of the United States.

The art of making hydrofluoric acid is an ancient art. It has long been known that when fluorspar (calcium fluoride, CaF2) is caused to react with sulphuric acid (H2SO4), hydrofluoric acid gas (HF) will be given off, leaving a residue of calcium sulphate (CaSO4). The reaction is generally expressed as CaF2 H2SO4 CaSO4 2HF.

Hydrofluoric acid is an extremely corrosive substance, which readily attacks glass and is destructive to the tissues of the human body. The pot still method of making hydrofluoric acid, which was in general use for many decades prior to Bishop, consisted in the use of pots or pans which were filled with fluorspar and to which sulphuric acid was then admitted. The workmen mixed these two substances with some suitable implement, and then a cover was bolted or fastened to the pan, after which, upon applying heat, the HF gases, coming off, were led through pipes to an absorbing system. The operation consumed about 48 hours before the treatment of one charge in one of these pans was completed. The conditions attendant upon such a process were troublesome, annoying, and dangerous to the workmen, who generally wrapped their hands and faces carefully with treated fabrics to prevent injury. When the reaction was completed, the cover was removed from the pan and the residue was in the form of a baked, hard, solid mass, comparable to a rock, which the workmen then had to remove with picks and other tools before the pan was ready for a new charge.

In addition to the method thus described, there were in the prior art other known methods of agitation of material in the still. Among those may be cited British patent No. 11,963 of 1889 (Defendant's Exhibit U), which covered agitation by blowing compressed air through reacting fluorspar and sulphuric acid; also British patent No. 189 of 1872 (Defendant's Exhibit S), which covered the operation of a rotating stirrer in a pot still in the process of producing gaseous hydrofluoric acid. There was also the Naugatuck process, which provided for the producing of gaseous hydrofluoric acid in a pot still, in which the reacting materials, fluorspar and sulphuric acid, were continually agitated, stirred, and broken up by a rotating stirring blade, and were heated to a gradually increasing temperature during the entire period of reaction.

Into this field came Bishop, whose process for the production of hydrofluoric acid involves the use of a revolving still or tumbling barrel, which continuously carries up the rising side and tumbles over in a cascade or avalanche the mixture of fluorspar and sulphuric acid during the reaction. By this process the reacting materials are placed in a proper proportion in a hopper, and through that hopper continuously fed into a revolving still, which is slightly tilted, so as to permit the residue of calcium sulphate to be taken from the still at the opposite end in the form of fine sand or powder, after the hydrofluoric acid gas has been extracted by the process of heating. Bishop, in his original application, made very particular claims for his invention, by which he claimed a patent monopoly of all possible methods of agitating fluoride and the acid, and the heating of such materials in all possible ways during the agitation thereof in the manufacture of hydrofluoric acid. Of these claims, Nos. 1 and 7, as originally filed, are fairly typical:

"1. The process of making hydrofluoric acid, which consists in agitating a fluoride and an acid and heating said materials during the agitation thereof."

"7. The process of making hydrofluoric acid which consists in agitating calcium fluoride and sulphuric acid, and subsequently simultaneously agitating said substances and heating them to gradually increasing temperatures."

The original seven claims filed by Bishop were rejected by the Patent Office, on the ground that the alleged process "apparently could be carried out in any receptacle provided with a stirrer and the heating means, for example, an ordinary frying pan on a cook stove." In response to this rejection, the present plaintiff, assignee of the Bishop patent, contending that the claims were nevertheless applicable, asked further consideration of them, with the result that they were again rejected; the Examiner saying:

"Upon further consideration, claims 1 to 7, inclusive, are not seen to be patentable, because of lack of invention. Putting the substances in a retort and shaking while heating is well within the claims and is a common method of procedure."

But still the plaintiff, not satisfied, again asked for further consideration, and again the Examiner rejected all the claims, stating: "It is common laboratory practice to place the reacting substances in a vessel, tube, beaker, flask, or retort, and shake or stir while heating, and no invention is seen in doing the same thing with calcium fluoride and sulphuric acid, particularly as these substances are commonly used in generating hydrofluoric acid."

After this rejection, the plaintiff canceled the seven original claims and substituted others, each specifying a gradual heating until the reaction was complete, or agitating the reacting substance to produce a solid in the form of loose particles. However, the Examiner again rejected the application, stating: "It is still considered to involve no invention to heat, while agitating, two materials which...