I remain, my dear Sir, Your’s truly, HERBERT MAYO. 19, _George Street, Hanover Square_, _August 29, 1827_. [p084] _Experiments on the Nature of Labarraque’s disinfecting Soda Liquid_. By M. Faraday, F.R.S., Corr. Mem. R. Acad. Sciences, Paris, &c. &c. 1. The following experimental investigations relate to the nature of that medicinal preparation which M. Labarraque has lately introduced to the world, and named _Chloride of oxide of Sodium_. They were occasioned by the accounts which were given of this and other substances of similar power, to the members of the Royal Institution, at two of their Friday evening meetings[31]; the value of the preparation, the uncertainty of its nature, and the inaccuracy of its name, all urging the inquiry. 2. In the first instance the inquiry was directed to the nature of the action exerted by chlorine gas upon a solution of carbonate of soda, questions having arisen in the minds of many, whether it was or was not identical with the action exerted by the same gas on a solution of the caustic alkali, and whether carbonic acid was evolved during the operation or not. Chlorine gas was therefore carefully prepared, and after being washed was sent into a solution of carbonate of soda, in the proportions directed by M. Labarraque; _i. e._ 2800 grains of crystallized carbonate of soda were dissolved in 1.28 pints of water; and being put into a Woulfe’s apparatus, two-thirds of the chlorine evolved from a mixture of 967 grains of salt with 750 grains of oxide of manganese, when acted upon by 967 grains of oil of vitriol, previously diluted with 750 grains of water, were passed into it; the remaining third being partly dissolved in the washing water, and partly retained in the open space of the retort and washing vessel. The operation was conducted slowly, that as little muriatic acid as possible might be carried over into the alkali. The common air ejected from the bottle containing the solution was collected and examined; but from the beginning to the end of the operation not a particle of carbonic acid was disengaged from the solution, although the chlorine was readily absorbed. Ultimately a liquid of a very pale [p085] yellow colour was obtained, being the same as M. Labarraque’s soda liquor, and with which the investigations were made that will hereafter be described.