Mr Middleton on Fluorine in Recent and Fossil Bones. 117 
bones operated upon being from the dissecting room :—the 
occiput, the vertebree, the humerus, the femur, the teeth, the 
femur of a foetus of 63 months. 
I examined also the arm, including the scapula, of a foetus 
of 33 months, but could obtain no evidence of the presence of 
fluorine in it; a result which, considering the small quantity 
of osseous matter involved, was perhaps to have been looked 
for. 
I determined also the presence of fluorine in the entoster- 
nal bones of the sternum of a recent tortoise. 
Any one who may continue to entertain doubt on this sub- 
ject, and whose object is the recognition and discovery of truth, 
may readily convince himself by using the means employed by 
me. I broke a portion of the bones to be examined into small 
fragments, and subjected them to the action of concentrated 
sulphuric acid, in a platinum crucible, covered, as is usual in 
such operations, by a plate of glass, endued with an etched 
coating of wax. I applied the flame of a spirit lamp from 
time to time, so moderating the heat as to sustain action of 
the acid upon the materials without projection upward of the 
substances against the glass. I prevent the melting of the 
wax by keeping a muslin rag, moist with alcohol, upon its 
upper surface. The time occupied by each experiment was 
between five and ten minutes. 
Through these and other investigations above alluded to, 
I have ascertained the presence of fluorine in the organic re- 
mains of Carnivora, Herbivora, Reptilia, Pisces, as also in 
the recent bones of Men and Reptiles. The increase of fluo- 
rine in fossil bones is apparently greater in proportion to the 
remoteness of the period at which they lived, where the cha- 
racter of entombment is similar. These facts, taken con- 
jointly, seemed to me to need, for their explanation, a more 
general source of fluorine than has been heretofore, I believe, 
supposed. It occurred to me, that ordinary water might be 
the vehicle ; and if so, the presence of fluorine in recent bones 
would not only be accounted for, but also its accumulation 
in fossil bones, being filtered from the moisture circulating in 
the earth’s crust. In order to ascertain whether facts would 
be found to sustain this view, I examined the following sub- 
