610 DR E. A. LETTS ON THE ACTION OF 
of dimethyl-thetine by heat, which I have already shown occurs according to— 
the equation— 
CH, 
| 
2|Br—S—CH,COOH ] = S(CH,COOH), + S(CH,),Br + OH,Br, 
CH, 
CH, 
| 
or 2|Br—S—CH,—COOH | = S(CH,COOH), + S(CH,). + 2CH,Br. 
| 
CH, 
During the whole of the experiment sulphide of methyl escaped through 
the vertical condenser, and was caught in the alcohol. Its presence was 
proved by the odour, and production of the characteristic compound with 
corrosive sublimate. 
The oily liquid precipitated by water was next examined. It appeared pro- 
bable that it consisted of thiodiglycollic ether, formed by the action of alcohol 
on the thiodiglycollic acid. It had much the same odour as thiodiglycolli¢ 
ether*—by no means pungent, and recalling faintly the smell of peppermint. 
Some of it was saponified with caustic potash, the resulting solution 
neutralised with acetic acid, and acetate of lead added ; this occasioned a white 
crystalline precipitate, which was collected and dried on blotting pape 
Determinations of lead gave the following numbers :— 
‘2285 gave 1948 sulphate of lead, = 58:2 per cent. lead. 
‘2795 =, ‘°2375 is ‘. 58:0 ‘ 
Calculated for S(CH,CO,),Pb, 58:3 a 
Another quantity was saponified with caustic baryta, and the solution 
on standing some time yielded the characteristic barium salt of thiodiglycollic 
acid, crystallising in blunt needles. 
These experiments show that pure hydrobromate of dimethyl-thetine, when 
boiled with alcohol, is resolved, even at the comparatively low temperature, 
into thiodiglycollic acid, and bromide, and sulphide of methyl. The pungent 
* Thiodiglycollate of ethyl has been studied by E. Scuunze (“Jenaische Zeitschr.” i. 472, 
477, 1864), who states that it may be prepared by the action of hydrochloric acid on an alcoholic 
solution of thiodiglycollic acid, and probably also by treating monochloracetic ether with sulphide of 
ammonium. According to Scuuuze, it is a colourless liquid, boiling with slight decomposition at 
240—-250° C., and has a feeble ethereal odour. Wishing to prepare some of the ether for purposes 
of comparison, I treated chloracetic ether with sulphide of potassium, and obtained a liquid which boiled 
constantly at 161-163° C., and which did not appear to suffer any decomposition when distilled. 
It possessed, however, all the properties of thiodiglycollic ether, and yielded thiodiglycollic acid by 
saponification with potash—precipitation with acetate of lead, and decomposition of the resulting lead 
salt by sulphuretted hydrogen. 

