NATURAL SCIENCES OF PHILADELPHIA. 99 



a very interesting table of the degrees of solubility of the various basic-Phos- 

 phates of Lime iu water saturated with carbonic acid gas.'-" 



It is not only in carbonic acid waters that Phosphate of Lime is soluble ; 

 basic-Phosphate of Lime dissolves in 3.150 parts of water, containing one-twelfth 

 by weight of Chloride of Sodium. The presence of Chloride of Ammonium in- 

 creases the solubility still more.* 



It is probable, therefore, that the solubility of the Phosphate of Lime Guano 

 rock from Los Monges is owing to the presence of the Chloride of Sodium exist- 

 ing in it. By reference to the analyses (II and III), it will be seen thai the 

 Phosphate of Lime dissolved is in proportion to the Chloride of Sodium in the 

 specimens. This will, however, require more detailed examination. 



Though the rock from Centinella containing so large a percentage of Phos- 

 phoric Acid combined with Iron and Alumina may seem at first worthless as a 

 fertilizer, no positive opinion should be formed or expressed without a very 

 careful investigation of the subject, which I believe has never yet been made. 

 It is true that Phosphate of Alumina is one of the most sparingly soluble sub- 

 stances known, though it is soluble in water saturated with Carbonic Acid, ac- 

 cording to Bischof in about 6.828.000 parts, though in the water of the Carlsbad 

 springs about double this quantity is held in solution, viz : ' t 



3-125000. 



Though the Phosphate of lime is applied to soils, and, as such, taken up by 

 plants, there is no proof that it remains in that form until the plants have need 

 of it; it enters into new combinations, some of which may be quite as insoluble 

 as this Centinella rock. The Phosphate of Lime dissolved by the carbonated 

 waters always found more or less in soils, J is decomposed by alkaline carbonates : 

 the lime would therefore be converted into a carbonate, and a phosphate of the 

 alkali will be formed.^ Bousingault and Levy, Journ. des Debuts, Dec. 5, 1852, 

 found that the air in the insterstices of arable soils contained as much as 22 

 to 23 times as much carbonic acid as the atmosphere, and when the soil has 

 been recently moistened 245 times as much. Phosphate of lime lying in such a 

 soil would be dissolved in a comparatively short space of time. 



Carbonate of Iron is present more or less in every soil, and consequently if in a 

 soil the carbonate of iron and phosphate of lime exist, both held in solution by a 

 carbonate of the alkalies, a mutual decomposition may take place||, consequently 

 we may have vivianite formed in the soil : instances are frequent of vivianite in 

 fossils of the green sand of New Jersey,^ but geological ages are not required 

 to produce these changes. M. Jerome Nickles has recognised its presence in 

 human bones, (Amer. Jour, of Sci. vol. xsi. p. 402.) he found in a cemetery at 



* Chem. and Phys. Geology, vol. ii% p. 28. 



f (Chem and Phys. Geol. vol. ii. p. 34. 



JResearches that have been made by Lassaigne, Journ. Chim. Med. 3 ser. iv. 

 354 ; and Ann. de Chim. et. de Phys. 3 ser. xxv. 346, show that phosphate of 

 lime is conveyed into the plants organism by water saturated with carbonic acid. 

 Dumas (Comptes Rendus, xxiii 1018,) holds the same opinion. 



I Bischof, Chem. and Phys. Geology, vol. i. p. 13. No. 19. Phosphate of lime 

 dissolved in carbonated water forms Carbonate of Lime, which is precipitated, 

 and alkaline phosphate which remain in solution. 



II Phosphate of lime dissolved in carbonated waters and proto-carbonate of 

 iron form a proto-phosphate of iron, which is precipitated, and bi-carbonate of 

 lime which remains in solution. (Bischof vol. i. p. 13, no. 20. 



^In the green sand of New Jersey, the decomposition is not owing probably 

 to the carbonate of iron, but to the sulphate resulting from oxydation of the 

 iron pyrities. (Bischof, vol. i. p. 14, no. 21.) Phosphate of iron and proto-sulph- 

 ate of iron form sulphate of lime and proto-phosphate of iron,) Similar changes 

 probably result in this guano rock, as in many specimens we find crystals of 

 gypsum recognizable with a pocket-lense. 



1857.J 



