C 3*5 1 
XVIII. Experiments and Observations on Shell and Bone. By 
Charles Hatchett, Esq. F.R.S. 
Read June 13, 1739. 
Some experiments which I lately made at the request of Mr. 
Home, and which he has done me the honour to mention in 
his ingenious Paper on the teeth of graminivorous quadrupeds, 
induced me to turn my attention more particularly to the che- 
mical examination of shell and bone, especially as the former 
appeared to have been hitherto much neglected. 
The time since these experiments were began, has not been 
sufficient to enable me to enter into all the minutiae of the che- 
mical analysis of these substances; but, as some remarkable 
facts were ascertained, I have now ventured to bring them for- 
ward, with the addition of some observations, although, as yet, 
the whole is little more than a very imperfect outline. 
The first of these experiments were made on the shells of 
marine animals; and, to avoid repetition and prolixity, I shall, 
in a great measure, once for all describe the menstrua, the pre- 
cipitants, and the mode of operation. 
When shells were examined, they were immersed in acetous 
acid, or nitric acid diluted, according to circumstances, with 
4, 5, 6 , or more parts of distilled water ; and the solution was 
always made without heat. 
The carbonate of lime was precipitated by carbonate of am- 
moniac, or of potash ; and phosphate of lime (if present) was 
previously precipitated by pure or caustic ammoniac. 
