inflamed taper, when in contact with the at- 
mosphere. The proportion in which it combines 
is represented by unity, or 1. It is procured by 
the action of diluted oil of vitriol, or hydro-sul- 
phuric acid on filings of zinc or iron. It is the 
substance employed for filling air-balloons. 
7. Azote is a gaseous substance, not capable of 
being condensed by any known degree of cold : 
its specific gravity is to that of common air as 
9516 to 10000. It does not enter into combus- 
tion under common circumstances, but may be 
made to unite with oxygen e by the agency of 
electrical fire. It forms nearly four-fifths of the 
air of the atmosphere \ and may be procured by 
burning phosphorus in a confined portion of air. 
The number representing the proportion in which 
it combines is 26. 
8. Carbon is considered as the pure matter of 
charcoal, and it may be procured by passing spirits 
of wine through a tube heated red. It has not 
yet been fused ; but rises in vapour at an intense 
heat. Its specific gravity cannot be easily ascer- 
tained ; but that of the diamond, which cannot 
chemically be distinguished from pure carbon, is 
to that of water as 3500 to 1000. Charcoal has 
the remarkable property of absorbing several times 
its volume of different elastic fluids, which are 
capable of being expelled from it by heat. The 
number representing it is 11.4. 
9. Sulphur is the pure substance so well known 
by that name : its specific gravity is to that of 
water as 1990 to 1000. It fuses at about 220° 
Fahrenheit ; and at between 500° and 600° takes 
