946' TRAKS'ACTIOirS of the AitEBICAN INSTITUTE. 



phosphate, then mixed with plenty of charcoal, and volatilized 

 act a high heat. Phosphorus is the resulting product. It is used in 

 the manufacture of friction matches, and also for the extermination 

 of vermin. The phosphoric nodules from the lower silurian rocks of 

 Canada, and the coprolites found in the fossiliferous rocks, are all of 

 organic origin, and contain phosphate of lime in various proportions 

 ranging from fifteen to eighty-five per cent. These nodules contain, 

 frequently, fragments of small shells ; such sometimes present a spiral 

 or other fdrm of interior structure derived from their animal organiza- 

 tion, Coprolites were first noticed by Buckland on the English coast, 

 but are now found in many other localities. They are used solely in 

 the making of superphosphate of lime ; while apatite containing a 

 uniform percentage of phospliate of lime, bids fair to compete with 

 the other substances already mentioned in the manufacture of the 

 vtirious chemical compounds. 



The superphosphate of lime obtained from the native phosphate of 

 lime, forms the base of various manures, which, if well prepared, 

 oannot but prove highly beneficial, as the sure means of communi- 

 cating phosphoric acid to the crops. They consist essentially of 

 superphosphate and sulphate of lime, with more or less undecomposed 

 bone phosphate and free sulphuric acid. When this compound is 

 scattered on the surfaces, it remains unaffected until rain falls upon 

 it, when it 'dissolves and trickles or soaks down into the soil, meeting 

 bere with its constituents (lime and potash), depositing here and there 

 a particle of bone phosphate, until the whole soil is filled with the 

 precious fertilizer. The superphosphate, as stated above, is prepared 

 fi'ora the apatite, eupychroite, phosphorite, coprolite and phosphatic 

 aodul«s,and also from bones, in which case it is called bone phos- 

 pkate^ because it contains the earth ingredient of bones. The 

 phiDsphoric acid is mostly combined with lime in all the genuine 

 guanos. According to the quantity of acid all these materials contain, 

 theiT market value is determined. A good superphosphate ought to 

 contain, according to Johnson, from twenty to twenty -five per cent 

 of phosphoric acid, partly soluble and partly insoluble in water, and 

 gome ammonia or ammonical salts. The soluble part is for quick and 

 energetic action, while the insoluable phosphoric acid renders its 

 effect more lasting. 



Gtiano, which, as well known, is formed from the excrements of sea 

 gulls, or fowls, pelicans and cormorants, and found in the torrid zone 

 • of tliis continent, consists essentially of phosphates, but more or- less 



