Royal Society. 141 



It ap])eared of interest to gain some insight into the constitution 

 of thialdine, which is the ]irototype 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 methyle pro- 

 mised to furnish some elucidation of this subject. 



Thialdine, dissolved in iodide of methyle, 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 recrystalUzing from alcohol. 



The crystalline compound produced iii this manner is the iodide 

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

 of equal equivalents of the two constituents. 



C12H13NS4 -h C2H3I - C14II16NS4I 



Thialdine. Iodide of Iodide of 



methyle. 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, 

 unchanged by potassa in the cold, this substance exhibits m general 

 all the characters which distinguish the iodides of tlie so-called 

 ammonium-bases. . 



The great mobility of the elements in thialdine, and especially 

 the large amount of sulphur which it contains, afforded but little 

 hope of successfully submitting the new iodide to the experiment 

 with oxide of silver, which is so characteristic for the ammonium- 

 bases. On adding oxide of silver to the aqueous solution of this 

 l)ody, which, as has been remarked already, possesses an acid re- 

 action, iodide of silver is formed, and the liquid assumes at once a 

 marked alkaline reaction ; but since the almost simultaneous formation 

 of sulphide of silver, and a powerful evolution of aldehyde, sntti- 

 cientlv indicate the perfect destruction of the compound, and since 

 experiment denotes the presence of ammonia in the liquid, it is im- 

 possible to decide whether the alkaline reaction observed after de- 

 composition is due to the liberation of an ephemeral ammonmm-base, 

 or to its product of decomposition. 1 • 1 r 



My experiments appear nevertheless to establish that tliialdme 

 belongs to the tertiary bases,— that it is a nitrile-base. 



fH 



Ammonia N < H 

 IH 

 Thialdine N { C,._j Hi.., S4. 

 To the complex molecule, 0,2111384, we must ascribe the faculty 

 ..f replacing the 3 equivalents of hydrogen in the ammonia. In 

 «lnil niunner, liowever, the elements are grouped m this complex 



