WE The American Naturalist. . 63% [April, 
fragments of bone well washed and dried, then the weight of 
the ashes, the difference may be consislered as representing the 
the weight of organic matter. 
The ash of modern bones is el of the following ele- 
ments: tribasic phosphate of lime in the largest proportion, 
with asmall quantity of phosphate of magnesia, very little, 
fluoride and chloride of calcium, carbonate of lime, very little 
peroxide of iron and of aluminum and, finally, an extremely 
small proportion of alkaline salts, as chlorides, sulphates and, 
possibly phosphates. 
In the fossil bones we will see that the proportions of phos- 
phate and of carbonate of lime vary, that those of magnesia 
and of chlorine change very slightly, while the fluoride of cal- 
cium is in a greater and more important quantity. There is 
often much more oxide of iron and sometimes phosphate of 
iron, sometimes crystallized silica, frequently a little sand or 
clay, and finally, in certain cases, sulphate of lime and pyrites. 
Complete Analysis. —This operation, performed upon modern 
bones, comprises the following : 
1.—Determination of fluorine. 
2.—Determination of chlorine. 
3.—Determination of carbonic acid. 
4.—Determination of phosphoric acid and the bases (lime, 
magnesia, alumina, and oxide of iron). 
1. Fluorine——The determination of fluorine is performed in 
the method described in detail in the Annales des Mines, 1st 
number; 1893, page 130; the general features of which, how- 
ever, are as follows: The decomposition of the fluoride in pres- 
ence of a great excess of silica by concentrated sulphuric acid, 
in an apparatus entirely dry, with a slow current of dry gas 
running through it; the transformation of gaseous fluoride of 
silicon into fluosilicate of potassium, which is collected, 
washed, dried and weighed. If the chlorine is in a quantity 
not to be neglected, it is absorbed by passing the current of gas 
through pumice impregnated with sulphate of copper and 
heated until the dehydration is complete, The same reagent 
