351 



100 parts of the Arenaceous Guano, from below the guano 

 rock, contain — 



Combined water 6.84 



Dry Organic matter . . . . • . 1-80 



Sulphate of Lime 7.00 



Bone Phosphate Lime and Magnesia . . 114.40 



Sand 0.60 



130.64 



Considering the mineral matter of each, that in 100 of guano 

 rock weighs SS^q, in 100 of arenaceous guano Oly^^ ; the pro- 

 portion of bone phosphate of lime and magnesia becomes 110 

 nearly in each, when an equal weight is taken. The question, 

 from whence does phosphate of lime, of this composition, come ? — 

 at once arises in the mind of any one who has a recollection of 

 the composition of fish bones, and especially the composition of 

 the ordinary Atlantic guano of the Aves, and other Islands. In 

 100 parts of calcined ox bone, there are 86 parts of bone phos- 

 phate of lime and magnesia and 14 parts of carbonate and silicate 

 of lime ; rarely 88.5 parts as given by Heintz. Fremy has 

 recently classed the bones of man, elephant, lion, calf, kid, ostrich, 

 serpents, codfish, and other fish as identical in composition. I 

 have found the bone phosphates of lime and magnesia, in the 

 burnt bones of the halibut, to equal 86.80 per cent., while the 

 bone and organic matter of the vertebra of this fish, as extracted 

 by acids, afforded 92 per cent, of the mixed phosphates. Taking, 

 therefore, the highest result on any fish bones, we have in the dry 

 matter only 92 per cent, of bone phosphate of lime and magnesia, 

 while 100 parts of the dry mineral part of the guano rock, afford 

 the phosphoric acid sufficient, when combined with lime, to pro- 

 duce 125 parts of the same salt. 



As we can look to no natural source for bones having the 

 composition of guano-rock, we inquire into the chemical influ- 

 ences exerted while the excrement of birds, mixed with more or 

 less of other animal remains, undergoes decomposition at a tem- 

 perature never lower than 85'^ F., moisture and water being 

 present. 



Experiment shows that under these conditions, the putrefac- 



