Analysis of Shells. 363 



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of incombustible matter left on the filter. Deducting this from 3.4, 

 the entire quantity before combustion, we have 1.8 gr. of combustible 

 or animal matter. The incombustible matter was found to be silex. 

 The 400 grs. of shell therefore contained, 

 Of silex, - - - 1.6 gr. 

 Of insoluble animal matter 1.8 gr. 



4. The solution (2) was now examined for the phosphate of lime, 

 of which it was suspected to contain a small quantity. Pure caus- 

 tic ammonia was added in excess; the liquid became cloudy, and af- 

 ter some time threw down a flocculent precipitate. The precipitate 

 was thrown upon a filter previously dried at 200° and weighed; it was 

 then well washed and dried again at 200°. The filter now weighed 

 7.5 grs. more than at first, which of course is the weight of the precip- 

 itate. It was found to be insoluble in sulphuric acid which showed 

 that it was not alumina, and before the blowpipe, it had all the char- 

 acters of phosphate of lime. We have therefore in 400 grs. of the 

 powdered shell, 7.5 grs. of phosphate of lime. 



The solution which was now freed from phosphate of lime, was 

 next tested for magnesia, but. no indication of its presence could be 

 obtained. The solution evidently contained no other earth but lime. 

 As a small portion of animal matter might probably be taken up, 

 by the acid, and thus the quantity, as obtained by the above process, 

 (3) fall short of the amount really present. Another mode of exam- 

 ination was adopted for the purpose of comparison, of which the fol- 

 lowing are the details. 



5. Of the powdered shell 400 grs. were dried at the temperature 

 of 200* and lost by the operation 6.5 grs. The mass was then ex- 

 posed in a platinum crucible, to a dull red heat, over a spirit lamp. 

 It became of a light brown color and lost several grains weight. It 

 was now exposed to a very bright heat in a furnace for half an hour. 

 On cooling, it weighed 379 grs. Its color was pure white. It was 

 somewhat caustic and had obviously lost a good deal of carbonic 

 acid as well as all its animal matter. To restore the former, the 

 mass was heated in a porcelain capsule, with a concentrated solution of 

 carbonate of ammonia, and the heat was continued at about 200 ; 

 until the mass became dry and the odor of ammonia ceased to be 

 exhaled. It now weighed 389.7 grains. 



Repeating the same operation on another 400 grs. and exposing it 

 to an intense white heat, the result was 272 grs. so that the mass was 

 almost pure caustic lime. Treated with carbonate of ammonia to re- 

 Vol. XXVI— No. 2. 47 



