44 Historical Sketch of Improvements in [July, 



and forming double salts, which have some permanency. Of 

 these he has described the following : 



Hyposulphite of potash-and-silver, 

 Hyposulphite of soda-and-silver, 

 Hyposulphite of ammonia-and-silver, 

 Hyposulphite of lune-and silver, 

 Hyposulphite of strontian-and-silver, 

 Hyposulphite of lead-and-silver, 



Thouoh the existence of this last salt has not been made out m 

 a satisfactory manner. (See Edinburgh Philosophical Journal, 

 i. 8 and 396.) 



15. Muriates. — The most generally received opinion at present 

 respecting the muriates is, that when dried so as to be totally 

 freed from water, they are in reality compounds of chlorine, and 

 the metallic base of the alkaline ingredient. This opinion is 

 chiefly founded upon the experiments of Gay-Lussac and The- 

 nard, and of Sir H. Davy. According to these gentlemen, when 

 the muriates previously reduced to a state of complete dryness 

 are heated with perfectly dry phosphoric or boracic acid, no 

 decomposition takes place i but if water be present, the muriate 

 is decomposed, and a quantity of muriatic acid is driven off. 

 M. Vogel, of Munich, has lately repeated these experiments 

 apparently with great care. He fused pure phosphoric acid and 

 muriate of barytes in separate platinum crucibles. They were 

 then reduced to powder, introduced into a platinum tube, and 

 subjected to a heat sufficiently strong to produce fusion. A 

 copious evolution of muriatic acid gas was the consequence. 

 The result was the same when fused muriate of tin, or muriate of 

 mano-anese, was employed . When boracic acid previously fused 

 was heated with dry muriate of potash, or of soda, muriatic acid 

 gas was hkewise evolved. (Jour, de Pharm. v. 61.) 



The obvious consequence deducible from these experiments is, 

 that we are not able to deprive phosphoric acid or boracic acid 

 of the whole of its water by exposure to a red heat. 



16. Sulph file of Magnesia. — M. Longchamp has published a 

 most elaborate set of experiments on this salt. He finds its 

 composition to be as follows : 



Sulphuric acid 33-751 5-000 



Magnesia 13-249 1-962 



Water 53-000 



100-000 



According to this analysis, the weight of an integrant particle 

 of magnesia woiikl be 2, and an atom of magnesium 1. This 

 differs so materially from preceding analyses, that chemists can- 

 not adopt it till the subject undergo further investigation. 

 5 



