590 



FARMERS' REGISTER— ANALYSES OF SHELLS. 



exposure lo heat was thus determined. This dif- 

 ference, obviously due lo the moi.«ture which had 

 escaped, was in one instance 3 grains, in tiie other 

 3.2 grains, giving an average of 3.1 grains of 

 water in "200 grains of powdered shell — or 1..5-5 

 grains per 100. Almost precisely the same re- 

 sults were obtained in another experiment made 

 afterwards. 



2. Four hundred grains of the powdered shell, 

 were digested in i)ure hydro-choloric acid, until all 

 the soluble matter was taken up. Two filters were 

 then prepared of Papier Joseph, of exactly equal 

 weight when dried in the sand bath. Through 

 one of these the liquid was carefully passed: the 

 filter repeatedly washed with distilled water and 

 then dried. Both filters were now exposed on (he 

 sand bath for a few minutes to bring them both to 

 the same state of dryness; and then they were 

 placed in opposite scales. The excess of weight 

 arising from the matter left by the solution on the 

 filler through which it had passed, was 3.4 grains ; 

 of this obviously only a part was animal matter, and 

 it became a matter of delicate experiment to de- 

 termine how much. In order to do this, as the 

 substance was too small in quantity to remove from 

 the filter, 



3. The filters were successively burnt in a pla- 

 tinum crucible, until nothing but a white ash re- 

 mained. The residue weighed as ioUows: 



That of the filter, containing the deposite 2.2 grs. 

 That of the filter alone, 0.6 grs. 



The former residue, viz : 2.2 grains, obviously 

 consisted in part of the proper ashes of the filter 

 itself This, amounting lo 0.6 grain being sub- 

 tracted, leaves 1.6 grain of incombustible matter 

 left on the filter by the .solution. But the entire 

 quantity of matter deposited on the filter, was 3.4 

 <T^rain; "deducting from this 1.6 grain, we have 1.8 

 grains of combustible or animal matter, which dis- 

 appeared in the combustion of the tiller. The in- 

 combustible matter was found to be silex. The 

 four hundred grains of shell, therefore contained 

 Of Silex, 1.6 gr. 



Of insoluble animal matter, 1.8 gr. 



4. The solution obtained [in 2,] was now exa- 

 mined 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 be- 

 came t loudy, and after some time a fiocculent 

 precipitate subsided. The solution was then passed 

 through a filler previously dried at the normal 

 temperature of 200° and accurately weighed. Of 

 course the precipitate was retained upon the filter. 

 The filter well washed in distilled water, to remove 

 any portions of adhering solution, was then dried 

 and brought to 200°. It now weighed 7.5 grains 

 more than at first. This excess obviously gives 

 the weight of the precipitate thrown down by the 

 ammonia. As the precipitate thus produced, might 

 have been alumina, as well as the phosphate of 

 lime — although the presence of the former was 

 not considered probable, an examination of the 

 precipitate became necessary. It proved to be in- 

 soluble in sulphuric acid, which showed that it was 

 not alumina, and before the blowpipe, it had all the 

 characters of phosphate of lime. This operation, 

 therefore, gives in four hundred grains of the pow- 

 dered shell, 7.5 grains of phosphate of lime. 



After the removal of the phosphate of lime from 

 the solution, a portion of the latter was tested lor 

 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 pro- 

 bably be taken up by the acid, and thus Ihe quan- 

 tity as obtained by the above process [3,] fall short 

 of the amount really present — another mode of 

 examination was adopted for the purpose of com- 

 parison, of which the following are the details. 

 In these experiments, the principal object being the 

 estimation of the animal matter of the shell, the 

 other ingredients are not particularly referred to. 



5. Four hundred grains of the powdered shell 

 were dried at the temperature of 200° — and lost by 

 the operation 6.5 grains. The mass was then expo- 

 sed 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 lor half an hour. 

 On cooling, it weighed 379 grains. Its color was 

 pure white. It was somewhat caustic and had ob- 

 viously 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 dr^ and the odor of ammonia ceased to be 

 exhaled. It now weighed 389.7 grains. 



The same operation repeated upon another four 

 hundred grains of the powder gave, after exposure 

 ibr some lime to an intense white heat, only 272 

 grains — so that the mass w.is almost pure caustic 

 lime. Treated with carb : ammonia to restore 

 the carbonic acid, its weight was 390 grains. The 

 average of these two results is 389.85 grains for 

 the earthy or saline matter contained in 400 grains 

 of the i)Owdered shell. 



Two parallel experiments were now performed, 

 each with 500 grains of the powdered shell — ex- 

 posed to a white heat in a Hessian crucible. Treat- 

 ed as before with carb : ammonia — they gave 487 

 and 486.6 grains respectively. These numbers 

 give an average of 486.8 grains of earthy or 

 saline matter contained in 500 grains of the pow- 

 dered shell, which corresponds lo 389 44 for 400 

 grains. This latter number differs from the re- 

 sults with the platinum crucible by ^^j^ of a grain, 

 a difference which is readily explained by the ad- 

 hesion of a small portion of the powder to the in- 

 terior of the Hessian crucible, a circumstance 

 which cannot be avoided. It will therefore be 

 more correct in this case instead of taking the 

 average by both crucibles, to rely upon the first 

 results with that of Platinum. 



Subtracting 389.85 grains from 400 — we have 

 10.15 for the moisture and animal matter contained 

 in 400 grains. The moisture has already [5,] been 

 determined to be 6.5 grains. The remaining 3.65 

 grains, would therefore appear to be animal matter, 

 By the direct process however, wo found the ani- 

 mal matter to amount only to 1.8 grains. It is to 

 be observed, that a part of the difference between 

 these two numbers, viz. 3.65 and 1.8, must be 

 ascribed to the unavoidat)le loss in transferring the 

 calcined powder from the crucible to the caj)sule 

 in treating it with carb: ammonia — and again, 

 in the operation of weighing. The remainder of 

 the difference may probably arise from the disapr 

 pearance of a small portion of animal matter by 

 solution, in the acid. We may therefore put down 

 for soluble animal matter and loss 1.85 grains. 



The quantity of carbonate of lime, not having 



