Sulfur mustard lewisite mixing with

The freezing point of sulfur mustard has been reduced in a number of ways to prevent the agent from solidifying in weapons in cold weather. In WWI, mustard was mixed with various solvents, e.g. carbon tetrachloride and benzene. In WWII, Britain produced it from thiodiglycol and hydrogen chloride as a 6 4 mixture with the oligomer T (Scheme 1.1), also known as O mustard. T has somewhat greater vesicant activity than sulfur mustard, is less volatile and more persistent. Other nations mixed mustard with lewisite, which also accelerated the onset of effects and increased the vapour hazard. 

Lewisite, CHCl=CHAsCl2, 2-chlorovinyldichloroarsine, named after its discoverer W. L. Lewis, was produced by the USA and shipped to Europe in 1918, too late to be used in WWI. Between the wars it was also produced by Japan and the Soviet Union. It is relatively easily made from arsenic trichloride and acetylene, although the process is technically more difficult than the production of sulfur mustard. Lewisite is more volatile (bp 190 °C) than sulfur mustard and hence it is less persistent it also appears to be more sensitive to environmental moisture. In contrast to sulfur mustard, its initial effect (skin pain or irritation) is almost instant, and blisters appear within a few hours. There has been no confirmed instance of use, although Japan is suspected of having used lewisite in China in WWII. In addition to being stockpiled as a neat agent, lewisite was mixed with sulfur mustard to speed up the onset of action and to depress the freezing point of the latter. 

Agent vapors of both series cause eye irritation. However, there is no significant difference in the concentration that will irritate the eyes and the one that will produce eye injury. Although impacts from exposure to vesicants occur almost at once, contact with vapors or the liquid agent neither irritates the skin nor produces visible dermal injuries until after a substantial latency period. In contrast, HL (C03-A010), sulfur mustard mixed with lewisite, produces immediate pain due to the arsenic mustard component. 

Lewisite (C04-A002) has been mixed with sulfur mustard (C03-A001) to prevent the sulfur mustard from freezing in the shell as well as to enhance its toxicity. 

Phenyldichlorarsine, ethyldichloroarsine, and methyl-dichloroarsine have similar properties and toxicities as lewisite. They may be mixed with sulfur mustard similarly as can be done with lewisite and mustard mixtures, and this can confuse the diagnosis between either an arsenical or a mustard injury. 

Formulation is also used to manipulate the fate of the agent. Soman, VX, Lewisite, and sulfur mustard can be mixed with high-molecular-weight thickeners to increase droplet size and thereby decrease primary vaporization. Such additives are generally used to promote efficient agent deposition on the target site. Thickeners can also increase agent persistence and may hamper decontamination efforts. 

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