588 DR E. A. LETTS ON THE 
B contains a quantity of lead which agrees with that required for a com- 
pound of one molecule of the base and two molecules of bromide of lead, and 
therefore similar in composition to the lead salts obtained from the hydro- 
bromate of dimethyl-thetine and of diethyl-thetine. 
(C,H,,SO.), 2PbBr, requires 45°5 per cent. lead. 
(C,H,,S0,), 3PbBr, ,,  48°7 be 
Up to the present time no other crystallised derivatives of dipropyl-thetine 
have been obtained. The aqueous solution of the hydrobromate is readily 
acted on by sulphate of silver to form the sulphate of dipropyl-thetine, and 
from this the hydrochlorate is obtained by the action of chloride of barium ; 
but both of these compounds could only be obtained as syrupy liquids, and even 
the chloro-platinate refuses to crystallise, and dries up to an orange-coloured 
syrup. 
. Hydrobromate of Di-isobutyl-Thetine-—7 grms. of bromacetic acid and 7 
germs. of isobutyl sulphide* were mixed and shaken. The acid dissolved with 
a considerable fall of temperature. The mixture was then heated in a water- 
bath and rapidly separated into two layers, the lower of which was very 
syrupy. The whole was left to itself for a night, and next morning the excess 
of sulphide of isobutyl poured off ; this amounted to 3:3 grms., and thus only 
about half of the sulphide was acted on. 
The syrup consists in all probability of hydrobromate of di-isobutyl-thetine— 
| : 
Br—S —CH,—COOH, 
C,H, 
but like the propyl compound it has not been obtained in the solid state, and 
therefore in a fit condition for analysis, so that its composition can only be 
inferred from the phenomena attending its formation and from its properties. 
The only crystallised derivatives that could be obtained from it were lead 
salts, for the preparation of which most of the aqueous solution of the crude 
thetine was employed. 
The solution was diluted, boiled with hydrate of lead till the latter ceased to 
be dissolved, then filtered and allowed to cool when an oily liquid precipitated. 
The supernatant liquor (1) was poured off and the oily liquid warmed 
with water, when it became crystalline almost immediately; the crystals 
* These represent equimolecular quantities. 

