374 Mr. Hatchett's Experiments on Zoophytes, 



I fully ascertained, that the phosphate of lime was afforded 

 by these substances only ; for, when the different skins from 

 which these scales and spiculae had been taken, were separately 

 examined in the like manner, no phosphate of lime was obtained. 



In addition to this I must observe, that the silver or pearly 

 hue of pearl, mother of pearl, and offish-scales, is only assisted 

 and modified by the relative degrees of opacity produced, in 

 mother of pearl and in pearl, by the interposition of the par- 

 ticles of carbonate of lime, and in the scales by phosphate of 

 lime ; for this peculiar lustre principally resides in the mem- 

 branaceous part, and remains with it when the acetous or 

 muriatic acids are employed as menstrua, but is completely 

 destroyed by the nitric acid. 



The horny scales of serpents, lizards, and such like animals, 

 differ from the foregoing ; as all of those which I have examined, 

 consist merely of the membranaceous or horny substance, in a 

 more or less indurated state, and appear to be devoid of phos- 

 phate of lime, as an ossifying matter.,. 



Horny scales in general, (and the scales of the Manis penta- 

 dactyla may be mentioned as an example,) afford but very slight 

 traces of gelatin after being long boiled in distilled water; and 

 this small portion of gelatin can only be discovered by the tan- 

 ning principle, and by nitro-muriate of tin, unless a very large 

 quantity of the scales has been employed. 



Human nail digested in boiling distilled water during several 

 days, was only softened ; and, like quill, afforded a slight cloud, 

 by the addition of nitro-muriate of tin. 



Shavings of ox's hoof, when long digested as abovementioned, 

 afforded a liquor which, in like manner, was only made slightly 

 turbid by nitro-muriate of tin. 



