found in the Guano Deposits and in their Vicinity. 549 



are derived, is clearly the percolation of water through the 

 guano beds dissolving out these salts, which running into lower 

 situations may be detained in lagoons and hollows of rocks, 

 where being subject to the high temperature of the climate 

 they would be evaporated down, leaving these salts in the 

 crystalline state described. As guano contains abundance of 

 these two salts, it is possible there may exist considerable 

 masses of them ; should this be the case, it is evident that to 

 the chemist in particular it would be of great interest as an 

 additional source of these valuable salts. 



The chance of finding any considerable quantity of guanite 

 in the state of crystals is not great, but as it forms one of 

 the ingredients of guano it is a substance of some import- 

 ance. The application of it as a manure in combination with 

 other ingredients is likely to be highly beneficial, it being a 

 compound containing two important substances in an insoluble 

 state, namely, ammonia and phosphoric acid ; these may be 

 taken up by plants only as they may be required, and not be 

 liable to be dissolved out of the soil or evaporated like other 

 ammoniacal salts. 



The last substance which I shall describe was also found 

 imbedded in the guano from Saldanha Bay ; it consists of 

 small globular particles composed of concentric lamina? slightly 

 adhering together, of a yellowish white colour, containing in 

 places portions of a similar nature, which on fracture have ap- 

 pearances of an organic structure like bone, but on examina- 

 tion by the microscope proved to be portions of shells resem- 

 bling Nummulites. On analysis I found the substance to be 

 composed of — 



37*50 parts Carbonate of lime. 



32*50 ... Carbonate of magnesia. 



12*00 ... Phosphate of lime. 



12*00 ... Water with a little ammonia and animal 

 matter. 

 3*00 ... Sand. 

 2*50 ... Alkaline sulphates and chlorides. 



99*50 

 There does not appear to be any great quantity of this sub- 

 stance. How it has been formed it is difficult to imagine ; 

 the composition is so very different either from that of bones 

 or shells, particularly in regard to the large quantity of car- 

 bonate of magnesia which it contains. It is however probable 

 that both bones and shells form the base of this substance, 

 and that partial decomposition having taken place, the mag- 

 nesia may have subsequently entered into combination with 

 the carbonate and phosphate of lime. 



