ijoo .-. Theory of CombuJlioh.'^On Shell and Bone, , 



intelligible, nay probable, if not the true reafon of all tht phenomena of fire, which, as it hai 

 been found by writers and philofophers of all ages a matter of no fmall difficulty, as may 

 be fufficiently underfliood by their ftrange hypothefes, and unintelligible folutions of fome 

 i&w phenomena di it ; fo will it prove a matter of no fniall concern and ufe In human 

 affairs, as I fliall elfewhere endeavour to manifeft, when I come to Ihew the ufe of the air 

 in refpiration, and for the prefervation of the life ; nay, for the confervation and refto- 

 ration of the health, and natural conftitution of mankind, as well as all other aerial ani- 

 jnals, as alfo the ufes of this principle, or propriety of the air in chemical, mechanicalt 

 and other operations. In this place I have only time to hint an hypothefis^ which, if God 

 permits me life and opportunity, I may elfewhere profecute, improve, and publifli. 



VI. 



Experiments and Ohfervations on Shell and Bone. By Cbarles Hatchett, Efq. F. R. S, * 



OOME experiments, which I lately made at the requeft of Mr. Home, and which he has 

 done me the honor to mention in his ingenious paper on the teeth of granivorous qua- 

 drupeds, induced me to turn my attention more particularly to the chemical examination 

 of fhell and bone, efpecially as the former appeared to have been hitherto much neglefted. 



The time fince thefe experiments were began, has not been fufficient to enable me to 

 enter into all the minutiae of the chemical analyfis of thefe fubflances; but as fome re- 

 markable fads were afcertained, I have now ventured to bring them forward, with the 

 addition of fome ohfervations, although as yet the whole is little more than a very imper- 

 feO. outline. 



The firft of thefe experiments were made on the Ihclls of marine animals; and to avoid 

 repetition and prolixity, I fliall, in a great meafurc, once for all, defcribe the menftrua, 

 the precipitants, and the mode of operation. 



When {hells were examined they were immerfed in acetous acid, or nitric acid diluted, 

 according to circumftances, with 4, 5, 6, or more parts of diftilled water ; and the folu- 

 tion was always made without heat. 



The carbonate of hme was precipitated by the carbonate of ammoniac, or of pot-afh ; 

 and phofphate of lime (if prefent) was previoufly precipitated by pure or cauftic am- 

 moniac. 



If any other phofphate like that of foda was fufpefted, it was difcovered by folution of 

 acetlte of lead. 



Bones and teeth were alfo fubjeded to the a£lion of the acetous, or diluted nitric and 

 muriatic acids. 



* Philof. Tranf. 1799. 



The 



