48 . III. DIST. CHAR. Mode. 



Oxide of carbo?i is common in vegetable conser- 



will be acceptable. According to the experiments of this gentleman, 



Shells, in substance, are either porcellaneous or of nacre (mother 

 of pearl). The porcellaneous have an enamelled surface ; and 

 their texture is generally fibrous. They consist of carbonate of 

 lime and a small proportion of gluten. Those of nacre have, 

 generally, a rough exterior surface, and a stratified structure. 

 They consist of a membranaceous substance hardened and in- 

 termixed (stratum super stratum) with a small portion of car- 

 bonate of lime. 



Madrepores and millepores consist, also, of carbonate of lime ce- 

 mented by gluten, or connected, in various ways, with a mem- 

 branaceous substance, which appears to be merely a modifi- 

 cation of gluten. 



Tubipores are composed of carbonate of lime and a membrana- 

 ceous substance. 



Corallince and Flustra hold, in some instances at least, phos- 

 phate of lime, in their composition, as well as the corbonate 

 the membranaceous part is in the same state, as that in the 

 madrepores, c. 



hides consist of a cartilaginous and horny substance regularly 

 organized The calcareous matter, principally carbonate of lime, 

 sometimes mixed with the phosphate. 



Gorgonia vary considerably in their composition. In general 

 they consist of two parts ; a horny substance, which forms the 

 principle and interior portion of their stems, and a more friable 

 or cretaceous matter, with which the foregoing is invested. The 

 horny part contains phosphate of lime, but scarcely any carbo- 

 nate. The outer part, carbonate, with scarcely any trace of the 

 phosphate; and is united with a soft, membranaceous substance. 



Echini (their shells or crusts) are carbonate of lime, with a small 

 mixture of the phosphate, cemented by gluten. 



The crust aceous covering of marine insects, (crabs, lobsters, fyc.) 

 contain both carbonate and phosphate of time, but the first in 

 the greatest proportion. 



