of Edinburgh , Session 1878-79. 
55 
Analysis agrees with the formula 
{(CH 3 ) 8 S} 2 S 2 0 6 , h,o. 
Ou heating the salt to about 120° C., it loses water, and on 
raising the temperature to 220° C. sulphurous acid is given off, but 
at first no sulphide of methyl. After some time, sulphide of methyl 
begins to come off also, and the substance melts. Heat was applied 
until the melted substance, which had been perfectly clear, turned 
slightly brown, and the evolution of gas almost ceased. 8’015 
grammes were found to have lost 3 ’325 grammes = 41 *4 per cent. 
The loss of one molecule of water, one of sulphurous acid, and one 
of sulphide of methyl, corresponds to 43*3 per cent. 
On cooling, the liquid solidified. The crystalline mass was very 
hygroscopic, and dissolved in alcohol. On adding ether, the salt was 
precipitated as a strong aqueous solution, which, on standing over 
sulphuric acid, yielded beautiful long fine prismatic needles. These 
were separated as well as possible from the mother liquid, by pressing 
between filter paper, and left for several days over sulphuric acid. 
Analysis agrees with the formula 
(CH 3 ) 3 S 1 so 
CH 3 j so * 
and an examination of its properties proved it to be the methyl 
sulphate of trimethyl- sulphine. 
(CH 3 ) 3 S— 0— S0 2 — S0 2 — 0 — (CH 3 ) 3 S = 
(CH 3 ) 2 S + S0 2 + (CH 3 ) — 0— S0 2 — 0 — (CH 3 ) 3 S . 
2, Experimental Determination of the E. M. F. of the 
Gramme Magneto-Electric Machine at different Speeds. 
By Professor Tait. 
3, On the Law of Cooling of Bars. By Professor Tait. 
[Part of this paper appears in the Transactions for 1877-78, 
having been inserted (as § 11*) in Professor Tait’s paper on Thermal 
and Electric Conductivity .] 
