Smoke FS agent

Si, and stannic tetrachloride. An effective smoke agent, whether it be mechanically dispersed from an aircraft spray tank or vaporized thermally, is a mixt of S trioxide and chlorosulfonic acid (FS smoke agent) which upon hydrolysis forms sulfuric and hydrochloric acid dispersions. Of course, all such formulations are highly corrosive, and, if not outright toxic, then conducive to pulmonary edema... 

FS. Chemical agent consisting of a mixture of SO, and chlorosulfonic acid used for producing smoke. It has been produced by the US Chemical Corps... 

The only disadvantage of FS is its highly corrosive action on metals and airplane fabrics, although in this respect it appears to be no than FM. Because of ita all-around superior qualities, FS has b< eii adopted os the standard liquid-smoke agent of the United States Army and Navy. 

The CWS stored some ammunition, smoke agents, and toxic agents, about eleven tons of FS smoke, 3,000 HC smoke pots, and nearly 500 tons of bulk toxics almost evenly divided between persistent and non-persistent gases. The departmental ordnance officers stored some toxic and smoke-filled ammunition. The departmental CWS carefully hoarded 32 4.2-inch chemical mortars, aware that the whole Army had only 44. ... 

FS a solution of sulphur trioxide in chlorosulfonic acid, was a standard smoke agent. When atomized it reacted with water vapor present in the air to form a dense cloud of droplets of sulphuric acid. 

A solution of sulfur trioxide [7446-11-9] dissolved in chlorosulfonic acid [7990-94-5] CISO H, has been used as a smoke (U.S. designation FS) but it is not a U.S. standard agent (see Chlorosulfuric acid Sulfuric acid and sulfur trioxide). When FS is atomized in air, the sulfur trioxide evaporates from the small droplets and reacts with atmospheric moisture to form sulfuric acid vapor. This vapor condenses into minute droplets that form a dense white cloud. FS produces its effect almost instantaneously upon mechanical atomization into the atmosphere, except at very low temperatures. At such temperatures, the small amount of moisture normally present in the atmosphere, requires that FS be thermally generated with the addition of steam to be effective. FS can be used as a fill for artillery and mortar shells and bombs and can be effectively dispersed from low performance aircraft spray tanks. FS is both corrosive and toxic in the presence of moisture, which imposes limitations on its storage, handling, and use. 

---