April, i92I. J CURRENT TOPICS. 569 substances examined. Amyl thioether (C~HnS) gave the highest odor with the smallest concentration, only o.4 mg. per cubic foot being sufficient to give strong intensity. Judging by market price alone, the two cheapest stenches which impart a strong odor are amyl acetate and nitrobenzene, but both of these are unsatisfactory because the odors are not unpleasant to many persons. Ethyi hydrosulphide (ethyl mercaptan, C2H~HS) and pyridin seem to be the only other stenches with highly disagreeable odors that are quoted at prices that seem worthy to be considered for large-scale use. Pyridin is especially suitable, for although the pure article is quoted at $2.5o per gallon, an impure article, which serves as well, can be obtained from the acid washings of light oils. Phenyl isocyanide has an extremely disagreeable odor, and, though not listed as a commercial chemical, can be prepared by comparatively simple and inexpensive methods.
Conservative figuring shows that gas can be probably satisfactorily impregnated with it at a cost of less than one cent per thousand cubic feet.
In view of the strong trend to electric supply for lighting and power, with the consequent relegation of gas to heating purposes, and, therefore, the low enrichment of it, the use of some powerful stench seems to be a necessity for the protection of life and property.
H.L.