20 INTRODUCTION. 
bling that of garlic. It is so combustible that, when 
melted, it should be kept under water, as it cannot 
be exposed to the air during this process without great 
risk of catching fire. This substance is not known in a 
native state ; and the whole of what is used in philoso- 
phy and commerce is obtained by different artificial pro- 
cesses. In union with oxygen (21) it becomes convert- 
ed into an acid, called phosphoric acid (25), and, under 
this form, in conjunction with lime, it constitutes the 
bones of men and animals. The greater part of the 
phosphorus of the shops is obtained from bones. 
48. Carbon is a name given to the pure inflammable 
part of charcoal. It is abundantly diffused through- 
out nature, for it enters into the composition of several 
minerals, and of all vegetable and animal bodies. The 
purest form under which carbon is known to exist is in 
the diamond (50). It may, however, be obtained suffi- 
ciently pure, for all common purposes, by burning apiece 
of wood, covered with sand, in a vessel called a cruci- 
ble. In combination with oxygen (21 ) it forms carbonic 
acid (26). Carbon is a chief component part of pit- 
coal (217), petroleum (213), and other bituminous sub- 
stances. 
