420 Dr. Muspratt 07i the Salts of Sulphuroiis Acid. 

 Represented per cent. — 



Theory. Found. 



1 eq. Suboxide of copper 891-39 9'36 10-67 



6 ... Sulphurous acid . 2407-02 25-62 24-44 



5 ... Soda 1954-50 20-52 



38 ... Water 4274-24 44-50 44-32 



9527-15 100-00 



This salt, when heated in a test-tube, first gives off large quan- 

 tities of water, then sulphurous acid, and the residue consists 

 pi-incipally of sulphates of copper and soda, with traces of 

 sulphur, &c. 



Sulphite of Copper and Ammonia. — I mixed a solution of 

 sulphate of copper with a large excess of sulphite of am- 

 monia, then put the mixture into a long wide tube containing 

 a thermometer, and apjilied heat. I removed the solution 

 from the sand-bath at 136° F., because at this temperature 

 silvery-looking flakes began to deposit, which powerfully re- 

 fracted the light. In a short time a large quantity of a 

 shining compound had separated, which when dried over 

 sulphuric acid and submitted to analysis gave the annexed 

 results : — 



8-690 grs. salt gave 10-73 sulphate of barytesss 2-952 grs. 

 sulphurous acid = 33*97 per cent. 



As these numbers agreed so closely with Bottinger's for- 

 mula*, — 



2(Cu20, S02)+NH''0, SOo4-3aq, 



I thought further determinations unnecessary. When this 

 compound is heated with water, it is decomposed and the red 

 gritty salt separates. Great care is required in the prepara- 

 tion of this sulphite, for it is difficult to prevent some of the 

 red salt depositing with it. The best way to obtain it in large 

 quantities, is to heat slightly a strong solution of sulphate of 

 copper with an excess of bisulphite of ammonia, then cork 

 the vessel and allow the mixture to remain undisturbed for 

 some days. 



All the sulphurous acid for my experiments was obtained 

 by the deoxidation of sulphuric acid by means of metallic 

 copper, — 



2S03+Cu=CuO, S03 + S02. 



* Liebig's Aunahii, bd. li. p. 411. 



