Dr. Muspratt on the Salts of Sniplmrous Acid. 415 



repose for some days under a bell-jar over sulphuric acid. 

 The crystals possess a cooling and sulphurous taste, and are 

 slightly alkaline to test-paper. 



Analysis: — 7" 10 grs. burned with chromate of lead gave 

 4"19 grs. of water = 59'01 per cent. 



Formula, NaO, SOg-f- 10 aq. 



Vauquelin has described a sulphite of soda of the following 

 constitution : — NaO, SOg -f 8aq ; and Rammelsberg analysed 

 one which agreed with the annexed formula : NaO, SOg 4- 'Jaq. 

 The varying proportions of water can only be accounted for 

 by the different temperatures at which the salts have been 

 formed. 



Bistdphite of Soda. — Dr. Rammelsberg obtained an acid 

 salt agreeing with the formula 2 (NaO, 2SOo) + aq. I find 

 however on referring to his results that the formula Na SOg 

 + HO SOg, which I gave in my former paper, corresponds 

 quite as well with his numbers as the one given by him. 



Sulphite of Ammonia. — I have not yet succeeded in pro- 

 curing from an aqueous solution an ammoniacal sulphite of 

 sufficient stability for analysis. The salts formed in alcohol 

 and aether, and heretofore described*, possessed the sub- 

 joined formiilae : — 



NH4O, SO, + aq. 

 NH4O, SO2 -j- SOg. 



I have produced another ammonia sulphite by passing sul- 

 phurous acid into a very strong solution of caustic ammonia 

 until there was no smell either of the acid or alkali, and then 

 adding cautiously absolute alcohol. After a short time a 

 brilliant white saline mass of crystals subsided, which were 

 allowed to remain undisturbed for twenty-four hours. I threw 

 the whole on to a filter and dried the crystals over sulphuric 

 acid. This salt is alkaline, and evolves traces of ammonia. 



Analysis: — 23*09 grs. of the salt gave 3.3-88 grs. svdphite 

 of barytes = 9*32 sulphurous acid or 40*36 per cent. 



The formula 2(NHp, SO2) + NHg-hSaq. requires 40-09 

 per cent, sulphurous acid. 



Sulphites of the Proto.vide of Iron. — Finely divided metallic 

 iron dissolves pretty readily in sulplnu-ous acid, imparting to 

 the liquid a slight green tinge. When this liquid is evapo- 

 rated in vacuo, very small and almost colourless crystals are 

 obtained, which are but slightly soluble in water. Exposed 

 to the air in a dry state they are not readily altered, but if 

 moist are rapidly converted into sulphate. I found my sul- 

 phurous acid, on analysing this compound, to agree so closely 



* /Inn. C/iem. und Pharm., Bd. 1. p. 285. 



