7 ” 
TT 
DIMETHYL-THETINE AND ITS DERIVATIVES. afd 
though to a less extent, in sulphide of methyl. It is insoluble in ether. After 
drying on filter paper the crystals often become brown on the surface ; this 
also occurs with the ethyl compound, and has been noticed with bromacetic 
acid itself. 
Hydrobromate of dimethyl-thetine yields magnificent orange-coloured crystals 
with chloride of platinum; these are probably isomorphous mixtures of the 
chloro-platinate and bromo-platinate. 
Bromaurate of Dimethyl-Thetine—This salt was obtained in beautiful, 
glittering, dark red scales, on mixing alcoholic solutions of bromide of gold and 
hydrobromate of dimethyl-thetine. It decomposes when heated to 100° C., 
and also when boiled with alcohol. It was not completely analysed. 
Bromo-Platinate of Dimethyl-Thetine was obtained in magnificent dark red 
erystals, resembling ferricyanide of potassium in appearance, by allowing a 
solution of hydrobromate of dimethyl-thetine and bromide of platinum to 
evaporate in a desiccator. 
The formula 2(C,H,SO,Br), PtBr, requires 21:3 per cent. of platinum, 
whereas 21°5 was obtained in two determinations. 
Hydrobromate of dimethyl-thetine is completely decomposed by nascent 
hydrogen, and, as might be expected, yields sulphide of methyl and hydro- 
bromic and acetic acids— 
CH, CH, 
| | 
Br—S—CH,—COOH + H, = S + H—CH,—COOH + HBr. 
| 
CH, CH 
3 
This decomposition occurs when the hydrobromate is treated with zinc and 
a dilute acid, and also when its aqueous solution is mixed with zine dust alone— 
the mixture growing very hot, and sulphide of methyl escaping in abundance. 
Hydrobromate of dimethyl-thetine has a pleasant sour taste, and its solu- 
tion reddens litmus. It acts readily on metallic carbonates, hydrates, and 
oxides, but the resulting compounds are not necessarily salts simply derived 
from the hydrobromate by the replacement of the hydrogen of its carboxyl 
group by metals; but are, in some cases at least, double salts, which may be 
conveniently represented as compounds of the base dimethyl-thetine with 
metallic bromides. Of these the most readily prepared is the— 
Double Salt of Dimethyl-Thetine and Bromide of Lead.—This salt is pro- 
duced when an aqueous solution of the hydrobromate is boiled with litharge, 
carbonate or hydrate of lead, but is most conveniently prepared by means of 
the latter. The hydrobromate is dissolved in a considerable quantity of water, 
and recently precipitated hydrate of lead is added. This at once becomes 
curdy, and, on warming the solution, gradually dissolves. The addition of the 
VOL. XXVIII. PART. II. 7K 
