bi2 PROFESSOR CRUM BROWN AND DRE. A. LETTS ON 
with hydrogen and electro-positive elements or radicals, triad and pentad 
phosphorus correspond to dyad and tetrad sulphur respectively, while in com- 
pounds with oxygen and electro-negative elements or radicals, triad and pentad 
phosphorus correspond to tetrad and hexad sulphur respectively. 
The following investigation was undertaken with the view of extending the 
number of comparable compounds by preparing a sulphur compound corre- 
sponding to betaine in the nitrogen series, and to the analogous phosphorus 
compound prepared by Hormann.* In this case the term in the nitrogen series 
exists, and is better known than that in the phosphorus series, so that we may 
compare our new substance to betaine, although probably it more closely 
resembles Hormann’s phosphorus base. 
We have given the substance the name thetine to recall its relation to 
betaine, and the fact that it contains sulphur. The salts of thetine may be 
regarded as compounds of sulphide of methyl, with substitution products of 
acetic acid; or as salts of trimethyl-sulphine, in which one atom of hydrogen 
in one methyl is replaced by carboxyl. Similarly, the salts of. betame may be 
regarded as compounds of nitride of methyl (trimethylamine), with substitution 
products of acetic acid, or as salts of tetramethyl-ammonium, in which one 
atom of hydrogen in one methyl is replaced by carboxyl. If other compounds 
of this kind are prepared, the nomenclature can easily be adapted to them; 
thus our base may be called dimethyl-aceto-thetine, just as betaine may be 
called tramethyl-aceto-betaine. 
These relations are best shown by means of graphic formule. Thus— 
CH, CH, - CH, .. 
NY fre 
CH :—N--“CH,(COOH) CH,—S--“CH,(COOH) 
L- 
| 
Br Br 
Hydrobromate of Betaine. Hydrobromate of Thetine. 
CH, CH, CH, 
Aer | 
CH,=N—CH, CH,—S—CH, 
| ate 
Br Br 
Bromide of Tetramethyl Bromide of Trimethy] 
Ammonium. . Sulphine. 
Free thetine may be regarded either as— 
CH, 
on—b—cH,—co 
O 
* Hormann, “ Proceedings of the Royal Society of London,” xi. 525. 

