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ELEMENTS OF MATERIA MEDICA.

So dee Hypochlo'ris. — Hypochlo'rite of So'da.

History. —The disinfecting power of a solution of this substance wasdiscovered by Labarraque about 1820 (Alcock, Essay on the Use of theChlorurets, p. vi). In the London Pharmacopoeia this solution is calledliquor sodee chlorinatm; in the French Codex , hypochloris sodicus aquasolutus. It is commonly known in the shops under the name of chlorideof soda, liqueur de Labarraque, or Labarraque 's soda disinfecting liquid.Other synonymes for it are chloruret of the oxide of sodium , and oxymu-riate of soda.

Preparation. —There are two methods in use for preparing a solutionof hypochlorite of soda.

(a.) Process of the Pharmacopoeia . —Dissolve a pound of carbonate ofsoda in two pints of water ; then put four ounces of chloride of sodiumand three ounces of binoxide of manganese, rubbed to powder, into aretort; and add to them four ounces of sulphuric acid previously mixed' with three fluidounces of water, and cooled. Heat the mixture, and passthe chlorine, first through five fluidounces of water, and afterwardsthrough the above prescribed solution of carbonate of soda.

When chlorine gas comes in contact with a solution of carbonate ofsoda, three salts are formed : chloride of sodium, hypochlorite of soda,and bicarbonate of soda.

REAGENTS.

2 eq. Carbonate Soda.108

/2 eq. Carb c .A d . 442eq.Carb te . Si eq. Soda . . 32Soda 108 Jl eq. Oxygen. 8M eq. Sodium . 24-2eq.Chlo- {1 eq. Chlorine 36rine . . 72 \ 1 eq. Chlorine 36

leq. Hypochlor s .A d

PRODUCTS.

2 eq. J3icarb te . Soda .

152

1 eq. Hypoclil te . Soda 761 eq. Chlor de . Sodium 60

The essential and characteristic properties of this solution depend onthe hypochlorite of soda. The changes which take place in the manu-facture of chlorine have been already explained (p. 105).

(b.) Process of the French Codex . —Diffuse one part of dry chloride oflime (hypochlorite of lime) through 30 parts of water. Then add twoparts of crystallized carbonate of soda, previously dissolved in 15 parts ofwater. Filter the mixture. In this process a double decomposition iseffected; hypochlorite of soda is formed in solution, while carbonate oflime precipitates. This process is more easy of execution than theprevious one. By using the proportions here directed the solution ismuch weaker than that prepared by the process of the London Pharma-copoeia.

Properties. —The solution of hypochlorite of soda [liquor sodaschlorinates of the London Pharmacopoeia) has a yellowish colour, anastringent taste, and an odour of chlorine. It destroys the colour ofvegetable substances; as litmus, turmeric, and sulphate of indigo.Previous to bleaching them, it reacts as an alkali on turmeric paper, andinfusion of red cabbage. By evaporation, crystals are obtained, which byre-solution in water re-produce the disinfecting liquid. By exposure tothe air, the solution undergoes decomposition, and crystals of carbonateof soda arc formed.