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poisonous compounds but not to anything like the same extent. Thus, primary and secondary lewisites are both highly toxic vesicants, the pri mary form being more toxic and less vesicant than the secondary, while the tertiary form is very much less active and is practically of no value as a chemical agent. As the primary form is by far the most active, it is the form into which the mixture was practically all converted. Thus, wherever the term, "lewisite" is used without qualification, it will be understood to refer to primary lewisite (/3-chlorvinyldichlorarsine).

Pure lewisite is an oily colorless to light amber liquid, of 1.88 specific gravity, which boils at 190°C. (374°F.), yielding a dense vapor 7.1 times

Chaht XIII.—Manufacture of lewisite (flow sheet).

heavier than air with a faint odor resembling geraniums. It is readily soluble in the usual organic solvents and petroleum, but is not dissolved by water or weak acids. It is, however, rather easily and quickly decomposed by hydrolysis, yielding hydrochloric acid and an oxide of chlorvinvlarsine, according to the equation:

However, unlike mustard gas, one of the hydrolysis products of lewisite (ClCH:CH.AsO) is a vesicant nonvolatile toxic which is not readily washed away by rains. Hence, while lewisite may be quickly destroyed by hydrolysis in moist air and on watery terrain, its combat value is not lost, since ground which has been contaminated with lewisite will remain dangerous from its oxides for long periods of time. In other words, one should not regard hydrolysis as immediately destructive of the toxic and vesicant powers of lewisite, but as a process in which the compound

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