This is a civil action in which the plaintiffs sought the issuance of a patent. The District Court, after trial, rendered a memorandum opinion, 1 made findings of fact and conclusions of law, and dismissed the complaint.

A patent had been issued to one Thacker, covering the manufacture of carbon disulfide from hydrocarbons, particularly specifying methane as the preferred starting material. The plaintiffs in the present action endeavored to produce a process for the manufacture of carbon disulfide from natural gas, following the Thacker process. Thejr discovered that, when they attempted to use natural gas containing large amounts of high molecular weight hydrocarbons, the apparatus used in the process clogged with tars and other similar material. They reduced the amounts of these hydrocarbons in the natural gas and found that the difficulty disappeared. The District Court found this discovery not to be invention, and we agree with that finding.

Affirmed.