580 PROFESSOR CRUM BROWN AND DR E. A LETTS ON 
A further confirmation of the above formula was afforded by the composi- 
tion of the double salt which the hydrochlorate forms with chloride of platinum. 
Chloro-Platinate of Dimethyl-Thetine.—This salt crystallises out in beautiful 
orange-yellow needles when tolerably concentrated aqueous solutions of the 
hydrochlorate and chloride of platinum are mixed. It is not very soluble in 
cold water, but is much more so in boiling water, from which it may be re- 
crystallised. It is insoluble in alcohol, and when heated with that liquid fuses 
below its surface, but becomes solid again on cooling. 
The salt obtained from aqueous solutions contains 2 molecules of water 
of crystallisation, and has the formula— 
2(C,H,$0,Cl), PtCl, , 2H,0. 
The salt was analysed by determination of water and platinum— 
Calculated in 100. Obtained. 
SSS 
Platinum; . : : 28°6 28°5 28°4 
Water, ; ; ; 5:2 5:4 
Hydriodate of Dimethyl-Thetine.—Up to the present time no salt having the 
composition of the normal hydriodate has been obtained. A solution of the 
base when warmed with hydriodic acid gradually becomes brown from the sepa- 
ration of free iodine. The same solution, not warmed but allowed to evaporate 
in vacuo over sulphuric acid, also became brown, and eventually deposited 
splendid lustrous crystals resembling permanganate of potash in appearance. 
Attempts to prepare the hydriodate from the sulphate of dimethyl-thetine and 
iodide of barium were equally unsuccessful, the solution of the hydriodate thus 
obtained decomposing during evaporation and yielding free iodine. 
In another experiment a very concentrated aqueous solution of the base 
was mixed with exactly the equivalent quantity of recently distilled hydriodie 
acid of constant boiling point. The mixture was then placed in a desiccator, 
and after a day or so yielded comparatively colourless crystalline crusts. These 
were found to contain 34:1 per cent. of iodine. They were recrystallised 
from a little hot water, and were then found to contain 33-4 per cent. of 
iodine. A hemi-hydriodate, having the composition expressed by the formula 
2(C,H,SO,), HI—<z.e, consisting of a compound of 2 molecules of the anhydrous 
base and 1 molecule of hydriodic acid, requires 34°5 per cent. of iodine—a 
number closely agreeing with that’ obtained with the product which had not 
deen recrystallised. Such a salt might be capable of existence thus— | 
OH, CH, 
WV 
| | 
I—S—CH,—C00—S—CH,—COOH, 
CH CH, a 

