Drying Oven: Electric Laboratory Oven with Thermostat and Wire-Wound Slabs (Cary-Curr, Sargent, 1914)

An electric oven for drying chemicals in the laboratory, from E. H. Sargent & Co. of Chicago. Slabs wound with resistance wire heat a ventilated insulated box. A thermostat bar inside it expands with the heat and snaps a switch open when the oven passes the set temperature, then closes it again as it cools. Wire shelves hold the dishes. Result: a thermostatic drying oven with adjustable ventilation and a lowest working temperature of about 60 °C. It draws about 3.6 A at 110 V with its switched heaters on. WARNING: the source builds the walls of transite and the base of asbestos and cement. Asbestos dust causes lung disease; cutting, drilling or breaking these parts releases it. Source: H. J. Cary-Curr (E. H. Sargent & Co.), US Patent 1,083,592 (1914). Unknown: sizes, the slab material, the metals. Ours: nichrome wire and a capacitor. Picture: patent drawing.