Muehleisen

This is a declaratory judgment action1, wherein the plaintiffs are seeking to invalidate U. S. Patent No. 2,501,962 issued to defendant Harold Ladd Pierce on March 28, 1950 under an application filed May 16, 1947. The defendant has filed a counterclaim alleging infringement. Inasmuch as I feel that the plaintiffs should prevail, the counterclaim naturally falls by the wayside.

As there are no jurisdictional questions involved, I can pass directly to the patent in suit. The patent “relates to methods and apparatus for expanding rock or earthy materials having a heat expansive component therein and has particular reference to improvements in the expansion of rock material having water of crystallization.”

The patent recites:

Grounds of invalidity of the patent as set forth by the plaintiffs are as follows:

The patent in suit is restricted to- a process for expanding perlite. To understand the patent its subject matter, perlite, should be defined. The Encyclopedia Americana, Vol. 23, pages 606-607, states as follows:

A more detailed description of perlite may be found in plaintiffs’ Exhibit No. 22, “A Descriptive Petrography of the Igneous Rocks,” by Albert Johannsen, University…