164 DR WILSON ON THE SOLUTION OF FLUORIDE OF CALCIUM IN WATER. 
of an organism. The law of final causes, in truth, would indicate that only 
a minute proportion of fluorine should occur in any organ ; for it would be peril- 
ous to an animal to introduce into its system a large quantity of fluorides, which 
can so readily be changed into the deadly hydrofluoric acid. Such speculations, 
however, are premature. It will be time enough, when many qualitative, but 
especially quantitative, researches have been prosecuted, as to the presence of 
fluorine in animal structures, to consider of what service it is to them ; if it be 
of any.. 
Enpinzurex, April 4. 1846. 

