Patent information:

Patent:Utility 1,409,953
Patented:March 21, 1922
Applied:May 15, 1920
Title:Ceramic Insulating Material
Description:Porcelain composition using Sillimanite for high electrical and mechanical strength and low coefficient of expansion, which is particularly suitable for spark plugs
Assigned to:Jeffery-Dewitt Co.

Patentee Information:

JEFFERY, Joseph A. Detroit, MI

Class and subclass information:

Subclass:144CERAMIC COMPOSITIONS Clay containing (e.g., porcelain, earthenware, etc.) And flint or feldspar Kaolin (e.g., ball clay, fire clay, etc.) containing;

Known specimens:

None known