CARBON. — SULPHUR. 
23 
and estimating the weight of 100 cubic inches of 
carbonic acid at 47.377 grains, every cubic yard of 
pure limestone would contain 17,092 cubic feet of 
carbonic acid gas. If, then, all the carbon contain- 
ed in the various rocks were set free over the sur- 
face, the quantity would be immense, and animal 
life immediately destroyed. It is well known that 
vegetation could not be supported without carbon. 
All vegetables absorb it, while animals give it off by 
respiration. Thus a purifying process is constant- 
ly going on by means of the vegetable kingdom, 
without which carbonic acid gas would soon abound 
to such an extent as to extinguish animal life. This 
gas is given off in immense quantities from numer- 
ous springs and fissures in the earth. M. BischofF 
estimates that 219,000,000 pounds of this gas are 
evolved from the vicinity of the Lake of Larch in 
one year, equivalent to nearly two billion cubic feet 
in volume. 
Sulphur is a well-known solid, brittle, shining sub- 
stance, of a bright yellow colour. When subjected 
to heat, it evaporates, and is condensed upon any 
cool substance, in the form of a fine powder, called 
■flowers of sulphur. Sulphur is most abundantly 
found in connexion with volcanoes,* from whence it 
* M. Von Leonhard, in his Lectures on Geology, remarks^ 
that "out of the crater of Parace, in Columbia, vapours of sul- 
phur rise so copiously, that crusts of sulphur eighteen inches 
thick are formed ; pieces of wood, exposed to the influence of 
these vapours for several days only, are covered with crystals? 
of sulphur. The rocks which surround the crater of Alaghez, 
the volcano from which flows such immense quantities of lava 
that they now load the plain of Armenia on the north, are en- 
tirely covered with sulphur; the inhabitants in the vicinity 
gather large quantities of it, and in a very peculiar manner. As 
the summit is inaccessible, they employ guns, as Dubois relate, 
and shoot through the covering of sulphur ; the pieces then fall 
down at their feet. The Greek island of Milo is very rich in 
sulphur. Numberless caves are full of sulphur and alum- 
When the walls of these caverns, which are covered with 
crystals of these substances, are illuminated, a most magnificent 
