40 
Proceedings of the Royal Society 
a most interesting nature. While the subject of the solution of 
different bodies in fused metals, although up to the present time it 
appears to have been almost entirely neglected, will also probably 
yield a rich harvest, and explain to us many things which are at 
present but imperfectly understood. 
The further development of this research is in progress. 
4. On Phosphorus Betaines. By Professor E. A. Letts. 
{Abstract.) 
The experiments of Professor Crum Brown and the author on the 
“ Thetines ” and their derivatives* have clearly shown that very 
striking analogies exist between certain compounds of nitrogen and 
sulphur. Thus sulphide of methyl closely resembles trimetliyl- 
amine (and ammonia), in many of its reactions, and in the products 
which it gives rise to. Like trimethylamine it combines with a 
molecule of bromacetic acid, and the resulting product, which 
was named hydrobromate of dimethyl-thetine, behaves in certain 
respects like the compound of bromacetic acid and trimethylamine 
(hydrobromate of betaine). 
Analogous phosphorus compounds have been obtained : in the 
ethyl series by Hofmann, f in the methyl series by A. H. Meyer. | 
The latter compound is simply the betaine salt in which the 
* Trans. Roy. Soc. Ed. xxviii. 
t A. W. Hofmann, “ Proc. Rry. Soc. Lond.” xi. 
X A. H. Meyer, “Bericlite d. deutsch. chem. Ges.” iv. 734. 
