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 mina and a large number of other highly useful compounds.

The electric oven, used for baking, drying, etc., at temperatures lower than those of the electric furnace, offers similar advantages of accurate temperature control, facility of operation and freedom from the contaminating effects of combustion. These ovens are now used in the preparation of hundreds of important products, ranging from pies and doughnuts to glassware, enamel ware, motor armatures, piano keys and watch dials. Chinaware is fired more easily and successfully in the electric oven than in combustion ovens, as the former provides a perfectly uniform temperature in all parts of the heating chamber, and any desired temperature can be exactly reproduced for each batch fired.

The electric "lehr" or annealing oven has recently come to the front in the glass industry. The quality of the glass annealed in it has proved so superior that many large users of glassware now specify in their orders, "must be annealed by electric lehr." One nationally known maker of ginger ale, after experiencing an average bottle breakage of two per cent in his filling machines, made the astonishing record of filling and capping 720.000 electrically annealed bottles, with the loss of only four from the entire lot!



To describe, even briefly, all the applications of electric heat in industry would require a large book which would be out of date by the time it was published, as interesting new developments are cropping up every day. The following are a few random details of the story:

Electric heat is used to stimulate oil wells that are running dry. Heating coils are lowered into the well to melt the heavy-oil accumulation and permit it to flow freely.

The evenness of heat essential to the correct curing and vulcanizing of rubber is automatically obtained by the use of electric apparatus to produce steam. In this process, the operation is confined to a single self-contained unit and does away with all piping.

Power and light companies find it profitable to use electric heat in purifying transformer oil. The oil is placed in a rotating apparatus which separates the suspended carbonized particles. The application of heat then vaporizes the contained water and other impurities, leaving the oil in proper condition to be used again.

In the preparation of effervescent salts, electric heat is found to be the most effective means of expelling moisture. It is now widely applied to drugs that must be packed in a perfectly dry condition.

Electric melting pots attached to typesetting machines are a boon to the printing industry. With the even temperature thus secured, the operator's attention is no longer diverted at frequent intervals to watching the thermometer, and production is said to be increased from fifteen to twenty-five per cent. Moreover, the appearance of the typography is much improved, as a sharp, clear type face results from maintaining exactly the right casting temperature.

Electric heat is used with great ad-