550 Royal Society i '^ 



prisms, which may be readily obtained upwards of an inch in length. 

 They are anhydrous, and perfectly stable at a temperature of 190° C. 



The composition of this salt is represented by the formula 

 C. [R, (NH,),] 4SO3. 



The silver salt is obtained by digesting oxide of silver with an 

 aqueous solution of the new acid. It forms large crystals, which 

 are easily soluble in water, but insoluble in alcohol or ether. They 

 '^"^taln C,(H2Ag,)4SO.,. 



The acid may be obtained by decomposing either the lead or silver 

 salt by hydrosulphuric acid, or perhaps more conveniently, by care- 

 fully precipitating a solution of the barium salt with sulphuric acid. 

 It is an exceedingly soluble and deliquescent substance, crystallizing 

 in long needles. It has a sharp acid taste, with somewhat of the 

 flavour of tartaric acid. 



For want of a more convenient name, we propose for this acid 

 the appellation of Methylo-tetra-sulphuric acid. Without wishing 

 to decide at present upon its constitution, its composition allows us 

 to consider it as formed by the association of marsh gas with four 

 equivalents of anhydrous sulphuric acid. 



In the reaction of sulphuric acid upon acetonitrile, two distinct 

 phases may be traced. In the first, the nascent acetic acid simply 

 combines with two equivalents of sulphuric acid ; in the second 

 phase, the acetic molecule undergoes a more thorough transforma- 

 tion ; faithful to its tradition it splits into carbonic acid and marsh 

 gas, which remains combined with four equivalents of sulphuric acid. 

 The new substance also may be regarded as sulphacetic acid, which, 

 losing carbonic acid, has assimilated an equal number of equivalents 

 of sulphuric acid. 



The two reactions may be represented by the following 

 equations : — 



, C^H.^ -I- 2H0 ^ .3HS0, = C,H,0, 2SO3 + NH.SO^.^^,^ 



_^ Acetonitrile. Sulphacetic acid. A 



^* C4H3N + 5HS0^ = a Hj 4SO3 + NH4 SO4 + 2C0,. 



Acetonitrile. Methylo-tetra- 



sulphuric acid. 



The action, then, of bases and of acids upon acetic acid presents a 

 remarkable analogy. 



The nature of the change which the acetic molecule suffers, is in 

 fact identical. Under the influence of both agents, it splits into 

 marsh gas and carbonic acid, but in the former case it is the car- 

 bonic acid which is fixed,- whilst in the latter it is the marsh gas 

 that remains in combination. 



The production of methylo-tetra-sulphuric acid calls to mind the 

 interesting substance, sulphate of carbyle, discovered by M. Magnus, 

 by combining olefiant gas with the vapour of anhydrous sulphuric 

 acid. Our new acid is however easily distinguishable from this 

 body, as well by its different composition as by its extreme stability ; 



