491 



hydration is assimilated by the products of decomposition, the sub- 

 stitution of ethylic potassa for the hydrate appears in many cases to 

 promise valuable results from this mode of ethylation. The facility, 

 however, with which ethylic potassa decomposes at a comparatively 

 low temperature, must always be a serious obstacle to an extensive 

 use of this reaction. 



II. "Contribution towards the History of Thialdine." By 

 A. W. HOFMANN, LL.D., F.R.S. Received May 30, 1857. 



Researches into the behaviour of several organic bases with bi- 

 sulphide of carbon, which I intend to lay before the Society at a 

 later period, have led to some experiments with thialdine, the 

 results of which I may be allowed briefly to state, since they are 

 but loosely connected with the principal object of the inquiry. 



It appeared of interest to gain some insight into the constitution 

 of thialdine, which is the prototype of an important class of alka- 

 loids containing sulphur. To what group of bases does this body 

 belong ? Is it a primary, a secondary, or a tertiary base ? The favourite 

 method of questioning bases by means of iodide of methyl pro- 

 mised to furnish some elucidation of this subject. 



Thialdine, dissolved in iodide of methyl, to which conveniently 

 its own bulk of ether has been added, furnishes after twelve hours a 

 solid crystalline mass, which may be readily freed from adhering 

 thialdine by washing with ether and recrystallizing from alcohol. 



The crystalline compound produced in this manner is the iodide 

 of a methylated base, generated, as proved by analysis, by the union 

 of equal equivalents of the two constituents. 



C 12 H 13 NS 4 + C 2 H 3 I = C 14 H 16 NS 4 I 



Thialdine. Iodide of Iodide of 



methyl. methylthialdine. 



The deportment of the new iodide resembles that of iodide of 

 tetramethylammonium, and the analogous iodides, which I have 

 described some years ago. Insoluble in ether, soluble in alcohol, 

 and precipitated from this solution by ether in the crystalline state, 

 soluble in water with an acid reaction, and separated from it again, 



VOL. VIII. 2 O 



