Sodium mercaptide and dibromosuccinic ether, in the proportion of two molecules of the former to one of the latter, were dissolved separately in absolute alcohol, and slowly mixed. A considerable evolution of heat took place, while sodium bromide separated out. The flask was then digested for some hours on the steam-bath. The alcohol was subsequently distilled off, and the residue, on cooling, was treated with water. An oil separated out. This oil was collected by means of a separating funnel, and the aqueous layer several times extracted with ether. The oil and the ethereal extracts were added together and dried over calcium chloride. Next morning the ether was distilled off at the ordinary pressure. The remainder was distilled in vacuo. Between 50° and 60° a few drops came over, which proved to be ethyldisulphide.The remainder came over between 150° and 170°.This latter fraction was redistilled, and a portion of it used for analysis. The boiling point at 20 mm. pressure was 160°.Combustion of dietthiosuccinic ether.Weight of substance taken = ·2477 gram.Weight of carbonic acid obtained = ·4476 gram.Weight of water obtained = ·1702 gram.