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 |
| Category: | Porcelain |
| Assigned to: | Jeffery-Dewitt Co. |
Patentee Information:
Class and subclass information:
| Class: | 501 | COMPOSITIONS: CERAMIC |
| Subclass: | 144 | CERAMIC COMPOSITIONS; Clay containing (e.g., porcelain, earthenware, etc.); And flint or feldspar; Kaolin (e.g., ball clay, fire clay, etc.) containing; |
Known specimens:
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