33" Mr. Hatchett’s Experiments 
form modifications of bone ; or according to their vicinity with 
such membranes or cartilages as are liable to such a change. 
If horns are examined, few I believe will be found to contain 
phosphate of lime in such a proportion as to be considered an 
essential ingredient. I would not be understood to speak here 
of such as stag or buck horn, for that has every chemical 
character of bone, with some excess of cartilage ; but I allude 
to those in which the substance of the horn is distinctly 
separate from the bone, and which, like a sheath, covers a 
bony protuberance which issues from the os frontis of cer- 
tain animals.* 
Horns of this nature, such as those of the ox, the ram, and 
the chamois, also tortoise shell, afford, after distillation and in- 
cineration, so very small a residuum, of which only a small 
part is phosphate of lime, that this latter can scarcely be 
regarded as a necessary ingredient. 
By some experiments made on 500 grains of the horn of the 
ox, I obtained, after a long continued heat, only 1,50 gr. of 
residuum; and, of this, less than half proved to be phosphate of 
lime. 
78 grains of the horn of the chamois afforded only 0,50 of 
residuum ; and 500 grains of tortoise shell yielded not more than 
0,25 of a grain, of which, less than half was phosphate of lime. 
Now it must be evident, that so very small a quantity cannot 
influence the nature of the substances which afforded it ; and 
the same may be said of synovia, 480 grains of which did not 
yield more than one grain of phosphate of lime. 
This substance is undoubtedly various in its proportions, in 
all these and other animal substances, arising probably from 
* Nature seems here to have made -an analysis or separation of horn from bone. 
