Appeal from the District Court of the United States for the Eastern District of New York.
Before MANTON, AUGUSTUS N. HAND, and CHASE, Circuit Judges.
AUGUSTUS N. HAND, Circuit Judge.
This is the usual patent suit brought by N. V. Philips' Gloeilampenfabrieken, the owner of United States patent No. 1,726,107, and Claude Neon Lights, Inc., its licensee, for infringement of claims 1 and 3. The invention, which was by Hertz, relates to electric discharge tubes, particularly to electric discharge tubes having a positive column light for lighting purposes. The commercial use of the tubes is for advertising signs.
The specification states that it was a known practice to introduce into a discharge tube having a gaseous filling of neon a little mercury in the form of a mercury drop, that by reason of the heating to which the mercury is exposed during the discharge it volatilizes and its vapor pressure so increases at a certain temperature that the mercury vapor begins to participate in the discharge and the positive light emitted by the tube is produced by radiation of mercury atoms, with the result that the red color of the neon changes to blue.
The inventor goes on to say that if the temperature of the surrounding air becomes too low the vapor pressure of the mercury in tubes of the above kind may so decrease that the blue mercury light will change to red neon light. He says that this disadvantage is eliminated or reduced if some other rare gases are used, for example, argon, and adds that krypton and xenon also will give favorable results. After the foregoing preliminaries, he describes his invention as follows:
"According to the invention a gaseous filling is introduced into a discharge tube with positive column light, which gaseous filling comprises argon and mercury vapor. The gaseous filling may consist of argon, krypton, xenon and mercury vapor.Preferably a gaseous filling of argon and mercury, the argon pressure of which is above 4 millimetres of mercury will be used. Discharge tubes according to the invention are capable of still producing mercury light at temperatures at which a discharge tube having positive light and filled with neon and mercury already produces neon light. This is a very remarkable phenomenon, as the exciting potential of argon is lower than that of neon. One would therefore expect that at a temperature at which a neon mercury discharge tube produces neon light, an argon mercury discharge tube of all others would produce only argon light, whereas experiment discloses that at certain temperatures the contrary is the case.
"A great advantage of the discharge tubes according to the invention consists in that their operating voltage is lower than that of discharge tubes having a positive column light and a neon mercury filling. The efficiency of discharge tubes according to the invention will likewise be greater than that of discharge tubes having a positive light and a gaseous filling of neon and mercury."
The claims relied on read thus:
"1. A discharge tube for positive column light, the gaseous filling of which comprises argon and mercury vapor."
"3. A discharge tube for positive column light, the gaseous filling of which consists of argon having a pressure above 4 millimetres of mercury pressure and of mercury vapor."
At first the defendant made tubes with a filling of argon and mercury but they are said to have proved commercially undesirable, owing to lack of continuous luminosity. Manufacture of these tubes ceased before the date of the issue of the patent on August 27, 1929. The only tubes alleged to infringe which were sold by the defendant prior to the filing of the bill of complaint contained mercury with a gas filling having 90 per cent. of argon and 10 per cent. of helium. This last ingredient was inserted to increase the temperature of the tube, and ever since the introduction of helium some rare gas was incorporated in addition to argon in order to provide heating and to keep up the temperature of the tube during cold weather. Since the filing of the bill, it has only sold mercury tubes with a filling of about 50 per cent. of argon and 50 per cent. of neon gas. The mercury tubes sold by the complainant have been of three kinds; one having argon to the amount of 2/15 and neon and helium to the amount of 13/15; one having 50 per cent of argon and 50 per cent. of neon; and a third having 80 per cent. of argon and 20 per cent. of neon.
The trial court did not pass upon the validity of the patent but dismissed the bill on the ground that the defendant's tubes did not infringe because they contained a rare gas other than argon or its permissible equivalents, krypton and xenon.
The question whether the defendant's tubes infringe is a close one. The complainant insists that the inventor made an important contribution to the art by combining argon with mercury vapor and that the addition of another rare gas, whether it was an ...