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VII. On the Spontaneous Decomposition of certain Sulpho- 

 methylates. Bij Arthur H. Church, Esq."^ 



IN the latter part of June 1853, I prepared a quantity of sul- 

 pliometbylic acid, and neutralizing the mixture of sulphuric 

 and sulphomethylic acids with finely-powdered native carbonate 

 of baryta of unusually excellent appearance, expected to obtain 

 sulphomethylate of baryta not far from pure ; biit the carbonate 

 of baryta was contaminated with a considerable amount of car- 

 bonate of lime, consequently the product was a mixture of sul- 

 phomethylate of baryta with the corresponding lime-salt : that 

 this was the case I did not discover, however, until the present 

 year. The mixed salts, crystallized, and dried between bibulous 

 paper, were set aside and forgotten until April last. The weight of 

 the salts was not less than 380 grms. The general formula of the 

 sulphomethylates, dried as just mentioned, is C^H^M2S0^-f 2aq. 

 The loosely- stoppered bottle containing the salts had been ex- 

 posed in diffused daylight for a period of twenty-two months before 

 it was disturbed. At the end of this time complete decomposition 

 had taken place, the bottle no longer contained a trace of the 

 original salts. At first three-fourths, the bottle was now little 

 more than half full; the upper portion of its contents was a 

 yellowish liquid of disagreeable odour and acid reaction ; the 

 lower was a white, apparently amorphous solid, but on this last- 

 mentioned substance there rested a crystalline crust, and from 

 this numerous distinct crystals sprang, their bases remote from 

 the light, and their summits inclined towards it. 



And first of these crystals, which were perfectly transparent 

 and colourless. Their hardness exceeded 1°*5, but was less 

 than 2°. The specific gravity of different specimens varied be- 

 tween 2-21 and 2-325. One of the largest crystals was 61 mil- 

 lims. in length and 2-5 millims. in breadth. The crystals belong 

 to the oblique prismatic system, and exhibit many interesting 

 modifications; their behaviour in polarized light was the same 

 as that of selenite. In some aspects their lustre is pearly, in 

 others vitreous. A qualitative examination indicated the presence 

 of calcium, sulphuric acid, and water; while the quantitative 

 estimation of these constituents in the crystals dried over sul- 

 phuric acid gave me the following numbers : — 



•5015 grm. furnished -2902 grm. of CaCO^. 

 •3031 grm. furnished '41 grm. of Ba SO^. 

 •3448 grm. lost on ignition "0514 grm. of HO. 



These results correspond with the following per-ccntage com- 

 position : — 



* Communicated by the Author. 



