DIMETHYL-THETINE AND ITS DERIVATIVES. 577 
liquid grew cloudy and gradually deposited oily drops, which did not crystallise. 
On evaporating the solution over a water bath a gummy mass was left, which 
did not invite a closer examination. 
Hydrobromate of dimethyl-thetine dissolved in water, and boiled with oxide 
of copper, yields a beautiful dark blue solution, which becomes of a magnificent 
purple colour when almost dry. If alcohol be added, purple flakes are 
precipitated, and alcoholic ammonia produces a magnificent dark blue crystalline 
precipitate. The blue solution obtained in the first instance when evaporated 
in vacuo over sulphuric acid gave eventually a purple syrup which would not 
erystallise. 
Alcoholic ammonia digested for a couple of days with the hydrobromate in 
a sealed tube at 100° C. gave crystals of bromide of ammonium. ‘The solution 
filtered from these gave a syrupy liquid, which, on evaporation, deposited crystal- 
line matter. This, however, was not examined more closely. 
Oxide of mercury, when boiled with the hydrobromate in aqueous solution, 
is gradually dissolved ; oily drops separate, which gradually become crystalline. 
They consist, in all probability, of a double salt. 
That the hydrobromate of dimethyl-thetine behaves as the hydrobromate of 
a base, and no longer possesses the properties of bromacetic acid, is proved, 
amongst other of its properties, by the reaction which occurs when its aqueous 
solution is treated with oxide of silver. The mixture becomes warm, bromide 
of silver is precipitated, and hydrated dimethyl-thetine remains in solution— 
CH, CH; 
Beak “on boon + AgHO = AgBr + Ho_4_cH,cooH. 
on, u, 
In the case of the action on hydrobromate of dimethyl-thetine of hydrates or 
oxides of metals, the bromides of which are more or less soluble in water, the 
bromide first formed combines with the base thetine to form a more or less 
soluble double salt. In the case, however, of the silver oxide, no such double 
salt is produced. 
_ Dimethyl-Thetine.-—This substance may be obtained either by the action of 
oxide of silver on the hydrobromate, or by action of carbonate or hydrate of 
bariufn on the sulphate of dimethyl-thetine. To prepare it with oxide of silver, 
a weighed quantity of the hydrobromate is dissolved in water and mixed with 
rather more than the theoretical quantity of oxide of silver.* The oxide at 
once becomes yellow, and the mixture grows very hot. It is digested for some 
* Conveniently rather more than the equivalent weight of nitrate of silver is converted into oxide by 
addition of potash solution, and the oxide employed without further weighing. (Equal weights of 
hydrobromatesand nitrate of silver were usually employed.) 
