Bengue anestile ethyl chloride anaesthetic cylinder, 1860-1940.
© Science Museum / Science & Society Picture Library
This bras cylinder was made in Paris, France and would have been used for the anaesthetic gas ethyl chloride. The cooling effect of the volatile liquid was used to produce local anaesthesia. The contents of the cylinder would be sprayed onto the site that needed anaesthetising and the area would be cooled by the evaporation of the liquid. For example this type of spray was used in dentistry to numb gums. The first apparatus of this type was Richardson's spray of 1866, invented by Benjamin Ward Richardson (1828-1896). Ethyl chloride (C2H5Cl) is used today as a local anaesthetic in pain-killing sprays for sports injuries and for minor surgical operations.