356 



It was deemed importivnt, 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 Peiai- 

 vian guano, where the conditions ai-e 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 dis- 

 engaged, 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 proximate 

 decomposition of the tri-hasic 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 proportion 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 am- 

 monia is readily formed from them. Perfect samples are, how- 

 ever, 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, accidentally present. This fact establishes a 

 resemblance which was unexpected, between the two diffei'ent 

 modes of decomposition of organic matter ; one in presence of 

 abundance of water ; the other, where mere moisture and decay- 

 ing 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 physi- 

 ological conclusions. Chemical physiologists, with hardly an 

 exception, consider the earthy part of bones as composed of tri- 

 basic phosphate of lime, bi-basic phosphate of magnesia, carbo- 

 nate of lime, and fluoride of calcium ; alkaline salts being occa- 

 sionally 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 de- 

 position take place, without derangement of vital functions. 



On looking over the evidence supporting this important con- 



