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Scientific American, Vol. 38, No. 7 (February 1878) (1878)

leaf 4

An illustration from Scientific American, Vol. 38, No. 7 (February 1878), 1878, leaf 4
iol's Apr aratuB.—The Mask. respired air to escape at the proper moment. On account of potass. This latter is for replacing the oxygen absorbed in respiration, and for adding a certain amount of humidity to ground on one side, like the focusing glass of a camera. Now the air, which makes it fresher… … © 1878 SCIENTIFIC AMERICAN, INC

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