316 Mr. Hatchett’s Experiments 
If any other phosphate, like that of soda, was suspected, it 
was discovered by solution of acetite of lead. 
Bones and teeth were also subjected to the action of the ace- 
tous, or diluted nitric and muriatic acids. 
The dissolved portion was examined by the abovementioned 
precipitants ; and, in experiments where the quantity of the 
substance would permit, the phosphoric acid was also sepa- 
rated by nitric or sulphuric acid. The phosphoric acid thus ob- 
tained, was proved, after concentration, by experiments which* 
being usually employed for such purposes, are too well known 
to require description. 
It is necessary moreover to observe, that as the substances 
examined were very numerous, and my principal object was to 
discover the most prominent characters in them, I did not, for 
the present, attempt in general to ascertain minutely the pro- 
portions, so much as the number and quality, of their respec- 
tive ingredients. 
The greater part, if not all, of marine shells, appear to be of 
two descriptions, in respect to the substance of which they are 
composed. Those which will be first noticed, have a porcella- 
neous aspect, with an enamelled surface, and, when broken, 
are often in a slight degree of a fibrous texture. 
The shells of the other division have generally, if not always, a 
strong epidermis, under which is the shell, principally or intirely 
composed of the substance called nacre or mother of pearl. 
Of the porcellaneous shells, various species of Voluta, Cy- 
praea, and others of a similar nature, were examined. 
Of the shells composed of nacre or mother of pearl, I selected 
the oyster, the river muscle, the Haliotis Iris , and the Turbo 
olearius. 
