532 ~ W.W.J. NICOL ON THE 
hydrogen over dry formiate of lead at a temperature over 100° C., small 
needle-shaped crystals separated out from the formic acid. These he believed 
to be thioformic acid (HCOSH), though in favour of this supposition he could 
only bring forward the sulphur analyses. 
I, Il. Theory for (HCOSH),. 
51:2 per cent. _ 52:5 per cent. 51°6 per cent. 
He made several unsuccessful attempts to determine the carbon and hydrogen ; 
finding 4 to 7 per cent. too much carbon, and 1°5 to 3 per cent. too much hydrogen. 
Again, in the “Journal of the Chemical Society,” xv. 278, W. J. Hurst states 
that he repeated the experiments of Limpricut with chiefly negative results. 
He also obtained crystals in the way described by Limpricut, which on 
analysis gave results differing both from Limpricut’s numbers and from those 
for theory. 
Theory (HCOSH). L II. III. 
C 19:3 27°9 29°2 28°2 
H 3°2 4:7 4°8 5:2 
Ss 51°6 58:7 52°8 56°7 
O 25°9 
100°0 
Horst assigns no formula to the body he thus obtained, but states positively 
that “it cannot be thioformic acid.” 
I then treated the solution obtained by the action of chloroform on sulphide 
of potassium with mercuric oxide to remove excess of sulphide if any, and if 
thioformic acid were present to form formic acid by the replacement of sulphur 
by oxygen; on filtering off the clear liquid and adding acetate of lead a white 
precipitate was formed which was sparingly soluble in water: this was washed, 
dried, and the lead estimated as sulphate giving— 
69°8 per cent. lead. Theory 1 eee \ Pb. 69°8 per cent. lead. 
I then prepared a large quantity of sulphide of potassium in the manner 
mentioned above, and placed a little of the alcoholic solution in a flask fitted 
with an upright condenser ; on warming the contents of the flask to about 50°C., 
and adding small portions of pure chloroform, the reaction took place with such 
a disengagement of heat that although the flask was cooled in water a portion 
of the alcohol passed off in vapour smelling strongly of mercaptan or some 
analogous compound ; at the same time chloride of potassium separated out as 
in the former experiment. When the further addition of chloroform produced 
no action, the whole was digested for several hours ina water bath, the chloride 
of potassium was then filtered off, and the clear solution distilled. The greater 
