ACTION OF SULPHIDE OF POTASSIUM UPON CHLOROFORM. 533 
part came over below 85° C., and smelt strongly of mercaptan, while the last 
portion consisted of water containing a few oily globules of a dark orange 
colour and a characteristic odour. 
The dark brown residue in the flask was treated with boiling absolute 
alcohol and filtered. The solution on cooling deposited a number of fine needle- 
shaped crystals, which were washed with alcohol till perfectly white, then dried; 
and on examination they were found to contain carbon, sulphur, hydrogen, and 
potassium. An analysis of the crystals gave the following result :— 
Potassium, : : 39°01 39'2 
Sulphur, : : 32'2 
On calculating the percentages of potassium and sulphur for thioformiate of 
potassium, we find potassium 39:09 per cent., sulphur 31:9 per cent. The 
potassium was estimated by converting the salt into sulphate by treating it 
with sulphuric acid. The sulphur was precipitated as barium sulphate after 
oxidation with nitric acid and chlorate of potassium. 
The solution in absolute alcohol was evaporated to a small bulk and allowed 
to cool, when a second crop of crystals was obtained, which, however, did not 
become colourless when washed with alcohol. With a view to recrystallisation 
they were boiled with ordinary proof spirit, when it was found that though 
soluble in absolute alcohol they did not dissolve in the spirit, but melted, and 
formed a distinct layer below the liquid. On treatment with successive 
quantities of spirit, the oily liquid became colourless, and on cooling solidified 
to an opaque white mass which was dissolved in water. The solution behaved 
with nitrate of silver like hyposulphite of sodium, forming a white precipitate 
which, slowly at the ordinary temperature, but rapidly on warming, became 
yellow, then brown, and ultimately black, owing to the production of sulphide 
of silver. The solution when acidified with nitric acid remained clear in the 
cold, but on warming became milky from separation of sulphur, and smelt of 
formic acid. Another portion, after acidifying in the cold with nitric acid, gave 
a white precipitate with acetate of lead. The whole was then precipitated as 
lead salt, and the lead estimated as sulphate. 
I. MUP 
64:09 64:19 per cent. of lead. 
The lead salt giving the above percentage of lead was boiled with a large 
quantity of water and allowed to crystallise (the undissolved part turned black 
on continued boiling), crystals soon formed, and on analysis gave— 
1G lis Theory for HOS | Pb. 
63:3 62°9 63:03 of lead. 
