Chemistry- ' 3H 



as to fuse the sulphuret of nickel which is formed. When cold water is 

 to be added, which will dissolve the sulphuret of potash, and leave the 

 sulphuret of nickel in the form of a yellow crystaUine powder, retaining 

 perhaps a little copper or cobalt but no arsenic, if the operation has been 

 properly conducted. If, however, the object is to procure nickel quite 

 pure, it should be fused a second time with sulphur and potash. 



The method of freeing cobalt from arsenic is the same as for nickel; 

 but it is then necessary to perform the operation a second time. The co« 

 bait (that of Tunaberg,) has never been perfectly freed from arsenic by one 

 operation, but has never retained any after the second.— «/<9wr7MiZ qfSciencd 

 for July 1827, p. 209. 



24. Experiments on the Nature of Labarraque's Disinfecting Soda Liquid. 

 By Mr Faraday. — The uncertainty concerning the nature of the disin- 

 fecting liquid of M. Labarraque, which was announced as a compound of 

 chlorine and soda, induced Mr Faraday to investigate the subject experi- 

 mentally, and he has conducted the inquiry with that sagacity and preci- 

 sion for which he is distinguished. The liquid was prepared by transmit- 

 ting well washed chlorine into a solution of carbonate of soda, in the pro- 

 portions directed by M. Labarraque ; that is, 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 mix- 

 ture of 967 grains of salt, with 750 grains of oxide of manganese, when 

 acted upon by 960 grains of oil of vitriol, diluted with 750 grains of water, 

 were passed into it ; the remaining third of the chlorine being partly dis- 

 solved in the washing water, and partly retained in the open space of the 

 retort and washing vessel. The gas was readily absorbed by the solution, 

 but from the beginning to the end of the process, not a particle of carbonic 

 acid was disengaged from it ; so that it contained chlorine, in addition to 

 the soda and carbonic acid. 



The resulting solution possessed all the characters of Labarraque's soda 

 liquid. It was of a very pale yellow colour, and had but little odour of 

 chlorine. Its taste was at first sharp, saline, and scarcely at all alkaline, 

 but with a persisting biting effect upon the tongue. When applied to 

 turmeric paper, it first reddened and then bleached it. When boiled, it 

 did not give out chlorine, nor undergo any other perceptible change, the 

 taste and bleaching power being nearly the same as before. This is a 

 decisive proof that the chlorine, though in a state ready to bleach or dis- 

 infect, must not be considered as in the ordinary state of solution, either 

 in water or in a saline fluid ; for ebullition will freely carry off the chlo- 

 rine under the latter circumstances. When brought to dryness by rapid 

 evaporation it left a dry mass containing scarcely any chlorate of soda, and 

 chloride of sodium, and which still bleached powerfully. Its bleaching 

 power compared to the liquid before evaporation was as 30 to 76. When 

 carefully evaporated, it gave a mass of damp crystals, which, when redis- 

 solved, had the taste, smell, and bleaching power of the original solution, 

 with almost equal strength. The effect of spontaneous evaporation was 

 very different. A portion of the bleaching liquid, set aside in an evaporat- 

 ing bason for six weeks, yielded crystals which had the appearance and 



