142 Royal Society : — 



molecule, whether we have here to assume a very unstable tribasic 

 radical, or whether special molecules are inserted for each of the 

 hydrogen-equivalents in the ammonia ; — to decide these points further 

 experiments are required. 



Liebig and Wohler, in their memoir on thialdine, state that the 

 whole of the nitrogen of this base is eliminated in the form of 

 ammonia, if the compound be decomposed by nitrate of silver. 

 This deportment appeared to furnish an easy mode of controUing 

 the formula of methylthialdine ; after the decomposition of this body 

 by nitrate of silver, I expected to find the whole of the nitrogen in 

 the residuar}^ liquid in the form of methylamine. On performing 

 the experiment, it was found that the liquid contained considerable 

 quantities of ammonia, but together with the latter alkali a fixed 

 base. This unexpected deportment reminded me of experiments 

 published several years ago *, on the action of oxide of silver on 

 thialdine, which is said to be thus converted into leucine. The 

 question presented itself, were the phenomeua observed in the pre- 

 sent case of an analogous character '! had the above experiment given 

 rise to the formation of methylated leucine ? 



Experiment proved that the decomposition of iodide of methyl- 

 thialdine by oxide of silver gives rise to the formation of ammonia 

 and of the oxide of tetramethylammonium 



NO, HO, 



-'2 -"3 J 



which was satisfactorily identified by the analysis of the gold- and 

 platinum-compound . 



The following equation represents this change : — 



4C,4Hi6NS,I + 20AgO + 2HO=4AgI+16AgS+12C4H4O., 



Iodide of methyl- Aldehyde, 



thialdine. 



-I-3H3N + C8Hi2NO,HO 



Hydrate of the oxide of 

 tetramethylammonium. 



The absence of any leucine-like compound among the pi'oducts of 

 decomposition of iodide of metbylthialdine induced me to repeat the 

 experiment on the actioia of oxide of silver upon thialdine itself. 



The transformation of thialdine into leucine, announced several 

 years ago, and apparently very intelligible by the analogy of the 

 formulae of the two bodies 



Thialdine C12 Hjg NS^ 



Leucine Cjg Hj.^ NO^, 



has not failed to rivet the attention of chemists. I wonder how 

 such an error could have crept into science ; for I have convinced 



* Goessmann, Chem. Gaz. vol. xii. p. 325. 



