128 PEOCEEDINGS OF THE SCIENTIFIC ASSOCIATION. 
is widely different. In appearance this mineral is deceptive, 
owing to the absence of the conchoidal fracture, bituminous 
odour and resinous aspect characteristic of ordinary asphalt ; 
its true nature, however, is revealed by its perfect solu- 
bility in various menstrua. 
Its indifference towards heat is remarkable, and is pro- 
bably owing to a deficiency of the lighter or more volatile 
constituents. Boussingault has shown that asphalt consists 
of a fixed principle called asphaltene , and a volatile one, 
petrolene. By keeping asphalt at a temperature of 250°C 
for forty-eight hours the volatile portion is driven off, and 
asphaltene remains as a black solid substance, which becomes 
soft and elastic at about 300°C, and decomposes before it 
melts (Watts, Diet. o/Chem., i., 426). It will be seen that 
the Williamsville mineral closely resembles asphaltene, and 
is probably an analogous or identical product formed by a 
natural process. 
The presence of sulphur in the mineral to the extent of 
8*814 percent, is a notable fact.* It appears to exist in the 
free state, and not in the form of pyrites (so universal in 
coal), because the ash was not found to contain the requisite 
amount of iron. The existence of sulphur in asphalt has not 
been recorded in any of the published analyses that have 
* The determinations of sulphur were made with great care, and 
two distinct methods were employed. By one the mineral was 
oxidised in the wet way with nitric acid and potassium chlorate, and 
by the other it was burnt with potassium nitrate and sodium car- 
bonate. The Resulting sulphuric acid was precipitated as barium 
sulphate. After being collected and weighed the precipitate was 
purified by heating with hydrochloric acid, and was then well 
washed and re-weighed, according to the directions of Fresenius. 
Blank experiments were also performed with all the materials, and 
proved their complete freedom from sulphur contamination. 
