![]() ![]() Easily and cheaply made, it performed well, but the discovery that it was also highly toxic meant that by the 1930s it had been replaced by tetrachloroethylene (known in the trade as 'perc' for its older name perchloroethylene), which has continued in use to the present day, though this too is now being replaced because of concerns about its carcinogenic potential.Ĭarbon tet (as it was affectionately known in the lab) also found its way into small fire extinguishers. The first dry cleaning agents, dating back to the mid-19th century, were petrol and kerosene, but these were embarrassingly flammable, so there was a move to find solvents that could still do the job but wouldn't burst into flames or cause machines to explode.Ĭarbon tetrachloride seemed an ideal choice. This strangely named process (it is only dry in the sense that water isn't involved) is used to clean fabrics that would be damaged by conventional washing. As a superlative solvent, it was an obvious product for dry cleaning. In the early 20th century, carbon tetrachloride found a multitude of uses. Today, the starting point is usually readily available methane - CH 4 - and plenty of chlorine, usually produced by electrolysis of salt water. He took chloroform, which is a similar molecule with one hydrogen atom instead of a chlorine, and reacted it with chlorine gas to make carbon tetrachloride. It was first made in 1839 by Henry Victor Regnault, probably better known as a physicist, but earlier in his career he was a busy investigator in organic chemistry. This simple compound of a carbon atom with four chlorine atoms attached is a clear, colourless liquid at room temperature and has a heady, almost fruity smell. Now I look back in some horror: today, we know carbon tetrachloride causes nervous system and organ damage and it may well be a carcinogen. We sloshed it around with abandon, making ready use of this solvent's ability to dissolve difficult-to-remove substances like oils and fats. ![]() At the time, carbon tetrachloride was an almost universal lab cleaner. ![]()
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