S 26 Mr. Hatchett’s Experiments 
is penetrated by it, and thus becomes more or less converted 
into the state of bone. 
It is also known, that the nature of the bone is more influ- 
enced by the greater or less predominance of the membrana- 
ceous or cartilaginous part, than by any other cause. It is 
not, therefore, for me to add any thing to this part ; and, in re- 
spect to the substance which is the cause of ossification, little 
also requires to be mentioned, for this (as has been already ob- 
served) is known principally to consist of phosphate of lime. 
I shall only, therefore, briefly mention the results of certain 
experiments. 
The bones of fish, such as those of the salmon, mackerel, 
brill, and skate, afforded phosphate of lime; and the only diffe- 
rence was, that the bones of these fish appeared in general to 
contain more of the cartilaginous substance, relative to the 
phosphate of lime, than is commonly found in the bones of 
quadrupeds, &c. 
The different bones, also, of the same fish, were various in this 
respect; and the bones about the head of the skate, only differed 
from cartilage, by containing a moderate proportion of phos- 
phate of lime. 
It is at present believed that phosphate, with some sulphate 
of lime, constitutes the whole of the ossifying substance ; and 
perhaps the formation of bone from cartilage, depends only on 
the phosphate of lime ; but, whether this is the case or not, it 
is fit that I should notice a third substance, which constantly 
occurred in the course of my experiments. 
When human bones, or teeth, as well as those of quadrupeds 
and fish, whether recent or calcined, were exposed to the action 
