290 ANNUAL OF SCIENTIFIC DISCOVERY. 



points in connection with the composition of the various phosphates of lime, 

 proceeding from changes during decay. He had stated in former communi- 

 cations, that the so-called bone phosphate of lime, of bones forming the 

 earthy part of the " phosphatic guanos/' or the guanos of the rainy latitudes, 

 in presence of decaying organic matter, had lost one, two, or more equiva- 

 lents of the lime base leaving a monobasic phosphate. In subsequent 

 actions, this lime disappeared by solution, while the apparently more soluble 

 phosphate remained. 



It was deemed important, at this stage of the investigation, to study the 

 changes which the bone phosphate had suffered in the midst of putrefying 

 matter, resulting in the production of Peruvian guano, where the conditions 

 are peculiar. Analyses of a number of samples, from the different localities, 

 have proved that in every case the lime of the bone phosphate has in part 

 become engaged with other acids ; the oxalic acid being generally the most 

 powerful acid present; while the phosphoric acid disengaged, has united to 

 ammonia and other bases found in the mass. This change of composition 

 in the bone phosphate, under entirely different conditions of exposure, is 

 interesting, apart from the additional evidence it affords of a natural proxi- 

 mate decomposition of the tri-basic phosphate, without the presence of abundance 

 of water. In this new case, it is true, the phosphoric acid finds other bases 

 to combine with ; while in those before reported it remains in larger propor- 

 tion with the lime and water only. It is generally believed that Peruvian 

 and similar guanos are alkaline in constitution, from the fact that carbonate 

 of ammonia is readily formed from them. Perfect samples are, however, 

 always in the acid state naturally, and a large part of the volatile matter 

 consists of salts of the volatile, oily acids and ammonia; carbonic acid being 

 rarely found, unless as part of calcareous matter, accidently present. This 

 fact establishes a resemblance which was unexpected, between the two dif- 

 ferent modes of decomposition of organic matter; one in presence of 

 abundance of water; the other, where mere moisture and decaying organic 

 remains are abundant. 



Another course of experimenting has been pursued on this subject of bone 

 decomposition, which had been alluded to before, and the results have a 

 more general interest, as they affect physiological conclusions. Chemical 

 physiologists, with hardly an exception, consider the earthy part of bones 

 as composed of tribasic phosphate of lime, bi-basic phosphate of magnesia, 

 carbonate of lime, and fluoride of calcium ; alkaline salts being occasionally 

 present. This mixture of earthy bodies, rarely definite, is subject to great 

 variations of proportions in disease, and it is so loosely connected with the 

 cartilage, that absorption and deposition take place, without derangement of 

 vital functions. 



On looking over the evidence supporting this important conclusion, one is 

 surprised to find that it is all derived from two courses of analytical inquiry. 



1st. Carefully cleansed and fresh bones are treated by means of dilute 

 acids, for the solution of the earthy salts, leaving the cartilage in nearly its 

 natural form. Carbonic acid is usually determined in this operation, and 

 the phosphoric acid and bases form the solution ; the acids and bases are 

 then apportioned by calculation. 



2d. Bones which have been washed, and reduced to coarse powder, are 

 heated with free contact of ah 1 , until the organic part of the cartilage is 

 destroyed; the remaining ash is then analyzed for acids and bases, and the 

 compounds calculated. 



