Labarraque Solution

LABARRAQUE SOLUTION, Labarraqua water, Eau (liqueur) de Labarraque, Liquor Natrii hypochlorosi, solution of sodium hypochlorite, containing NaCl and other impurities depending on the method of preparation. Berthollet (1785), discovering that chlorine is absorbed by potassium lye and this solution destroys colors, stains, etc., introduced it (Eau de Javelle; from the locality of Javelle near Paris) into use. The replacement of caustic potash with the cheaper caustic soda ensured this solution—already under the name L. s.—wide application. L. s. is prepared in large quantities electrolytically from NaCl, as well as by passing chlorine into a solution of caustic soda or a mixture of it with soda. Passing chlorine into a solution of soda alone gives a smaller yield due to the side reaction of chlorate formation that occurs under these conditions. In small quantities, L. s. is prepared by precipitating a solution of bleaching powder (calcium hypochlorite) with soda or Glauber's salt; in the latter case, the preparation contains an impurity of sulfates, but is less caustic than strongly alkaline solutions with soda. Labarraque solution was listed in former Russian pharmacopoeias with 1% active chlorine. L. s. for technical needs is sometimes prepared with up to 10% active chlorine. In medicine, it is rarely used; during the war, it was used for disinfection of wounds along with Dakin's solution. A very strong L. s. with an excess of caustic alkali is known under the name antiformin (see).