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XVI. Chemical Experiments on Zoophytes; zvitb some Observa- 

 tions on the component Parts of Membrane. By Charles 

 Hatchett, Esq. F. R. & 



Read June 12, 1800. 



X he experiments and observations on shell and bone, which 

 I had the honour last year to lay before this learned Society, 

 were made in consequence of my having discovered, some little 

 time before, that the enamel of teeth did not consist principally 

 of carbonate of lime, as was generally believed, but was of a 

 nature similar to bone ; with this difference, that the phosphate 

 of lime was not deposited in and upon a cartilaginous or mem- 

 branaceous substance, but was only blended with a certain 

 portion of animal gluten.* By the experiments subsequently 

 made on various shells, crustaceous substances, and bones, it 

 was proved, 



1st. That the porcellaneous shells resemble the enamel of 

 teeth in the mode of formation, but that the hardening substance 

 is carbonate of lime. 



adly. That shells composed of nacre or mother of pearl, or 

 approaching to the nature of that substance, and also pearls, 



* See experiments mentioned in. Observations on the teeth of graminivorous qua- 

 drupeds, &c. by Everard Home, Esq. F. R. S. Phil. Trans, for 1799, p. 243. 

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