of Edinburgh, Session 1878-79. 
89 
bustion. For combustion the crystals were collected on a funnel 
fitted with a platinum gauze cone, rapidly washed with ice-cold 
water, and dried on well-cooled filter paper. When dried as 
thoroughly as possible, they were rapidly placed in a weighed test 
tube, cooled in a freezing mixture, weighed, and inserted in an 
open combustion tube, the lower end of which was at a dull red 
heat. The combustion tube was filled with a mixture of three- 
fourths oxide of copper, and one-fourth chromate of lead, with 
a stream of oxygen passing through it. 
The following are the results of analysis : — 
I. *8515 gr. gave ’8355 H 2 0 and ’0525 C0 2 
II. -7655 „ -7530 „ *0380 „ 
III. *6820 „ *6620 „ -0365 „ 
The percentage of carbon is 
(1) 1-68 
(2) 1*35 
(3) 1-46 
equivalent to per cent, 
of mercaptan 
(1) 4-33 
(2) 3-49 
(3) 377 
The excess of carbon in No. I. is caused probably by the difficulty 
in obtaining a perfectly dry substance, free from adhering mercaptan. 
Direct estimations of sulphur have not as yet proved satisfactory ; 
in some experiments mercaptan was oxidised along with sulphuretted 
hydrogen, in other cases it was not. It is hoped that shortly a 
method may be obtained for the more accurate estimation of sulphur 
in this substance. 
From the above results it would appear that the chief constituent 
of this crystalline compound is water (not less than 90 per cent.), 
combined with a small quantity of mercaptan and sulphuretted 
hydrogen. 
With sulphide of ethyl, sulphuretted hydrogen, and water, no 
crystalline compound is formed at 0° C. With sulphide of amyl 
or with sulphydrate of amyl the results were also negative. 
With sulphide of methyl the formation of a crystalline compound 
is obtained with ease. To a small quantity of water at 2° C. a little 
pure sulphide of methyl was added, and sulphuretted hydrogen 
passed in. In a very few minutes crystallisation commenced, and 
sulphuretted hydrogen was absorbed. These crystals are more 
stable than those of mercaptan, and it is the writer’s intention to 
study this compound in order to discover whether it has a definite 
composition. 
