D. M. Steward Mfg. Co. developed insulators made of lava

[Trade Journal]

Publication: The Electrical Engineer

New York, NY, United States
vol. 11, no. 149, p. 320,323, col. 2,1



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A substance that is absolutely fire-proof, non-porous, and insoluble, having the rigidity of stone, and the non-conducting properties of dry air, appears certainly to combine in itself every quality desirable in an insulator.

The D. M. Steward Mfg. Company, of Chattanooga, Tenn., seem to have produced such a substance in their lava insulator, which is claimed to possess greater possibilities, and a wider range of application, than any other substance ever used for the purpose. It is equally effective for inside or outside use, underground or in damp places; it can be cut, turned, or molded into any shape required, before being hardened, and the process of hardening does not warp the pieces. Hence it may be made to fit any given place as accurately as brass, often a great desideratum to electricians. No heat, short of the electric arc, has any effect upon it, and, as it is perfectly non-absorbent, it can be used with no fear of damage in cellars, steamy rooms, or where exposed to the fumes of acids, etc.


Keywords:D. M. Steward Manufacturing Company : Lava Insulator
Researcher notes: 
Supplemental information: 
Researcher:Bob Stahr
Date completed:January 24, 2011 by: Elton Gish;