186 W. J- Taylor on Rock Guano. 



wltli water is no proof that it exists in a free state. Pliospliate 

 of lime, when recently precipitated^ is soluble to a slight extent 

 in pure water (R. Phillips^ Ann. Phil. 22, 188). Berzelius long 

 since discovered phosphates of lime and alumina in the water 

 and deposits of hot springs at Carlsbad,*^ That phosphates are 

 insoluble and must be rendered free before becoming efficacious 

 as fertilizers is an erroneous though a very prevalent opinion. 

 According to Bischof f phosphate of lime must be regarded as 

 resent in all water running into the sea; it has already been 

 elected in the waters of the Bee and of the Don, and it will 

 most likely be found in the waters of all rivers. Phosphate of 

 lime and magnesia have also been found in the waters of an ar- 

 tesian well at AVildegg, in the Canton Argan (Switzerland). 

 Phosphate of lime has been shown to be present in sea water by 

 Clemm:}: and by Forchhammer.§ According to Berzelius it is the 

 diphosphate which is found in the mineral waters,! which is 

 readily soluble in water saturated with carbonic acid. The basic 

 phosphate of lime is also readily soluble in water containing 

 carbonic acid; Bischof gives a very interesting table of the de- 

 grees of solubility of the various basic phosphates of lime in 

 water saturated with carbonic acid gas,^ 



It is not only in carbonic acid waters that phosphate of lime 

 is sohible; basic phosphate of lime dissolves in 3'150 parts of 

 water, containing one-twelfth by weight of chlorid of sodium. 

 The presence of chlorid of ammonium increases the solubility 

 still morel" 



It is probable, therefore, that the solubility of the phosphate 

 of lime guano rock from Los Monges is owing to the presence 

 of the chlorid of sodium existing in it. By reference to the 

 analyses (II and III), it will be seen that the phosphate of lime 

 dissolved is in proportion to the chlorid of sodium in the speci- 

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

 Though the rock from CentincUa, containing so large a per- 



centage of phosphoric 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 investiga- 

 tion 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 substances known ; still it is soluble in water saturated 

 with carbonic acid, according to Bischof in about 6,828,000 

 parts, while in the water of the Carlsbad springs about double 

 this quantity is held in solution, vi^. ^^^i^^^.^-' 



Gilberts Annalen. Ixxiv, 136. 

 f Chem. an.! Pliys. Geology, vol. 2, p. 27 (Engl edit). 



i Jaurn. fiir pnikt. CluMnie, sxxiv, 186. § Berzelius, JahresbericLt, xxvi, 393. 



I Gmelin, vol. iii, p. 195. ^ Chem. and Pbys, Geology, vol. ii, p. 28. 



** Chfim. and Phys. GeoL, voL li, p. 34. 



