Phosphatic Materials used for Agricultural Purposes. 377 
the phosphoric acid is united with magnesia and with lime, and 
the carbonic with lime. The traces of chlorine and sulphuric 
acid, in all probability, are present as sulphate of soda and 
chloride of sodium, 
Ey uniting together the analytical results in the same manner 
in which the constituents occur in bone-ash, we obtain for the 
ash of — 
Tribasic phosphate of lime, 
3 Ca 0 + P O,. 
Consisting of — 
Phosphoric acid . 
Lime 
Phosphate of Magnesia. 
2 Mg O, P O,. 
Consisting of — 
Magnesia 
Phosphoric acid 
Carbonate of Lime. 
Consisting of — 
Lime 
Carbonic acid 
Horae-bones. 
38-77 
45-24 
1-51 
Lime, neither united with phosphoric acidl 
nor with carbonic acid ]\ 
Potash 
Soda 
Chloride of sodium 
Sulphate of soda i 
•80 
•99 
84-01 
2-35 
86'36 
6-79 
5-97 
•25 
•03 
traces 
traces 
99-40 
0.\-I)(iiies. 
38-38 
44-77 
•80 
•43 
4-48 
3-52 
83-15 
2-23 
85-38 
8-00 
C-18 
•49 
•51 
-11 
•07 
100-74 
In perfectly pure bone-ash thus we find no more than 85^ to 
86^ per cent, of phosphate of lime and magnesia (bone-earth). 
It will be noticed that pure bone-ash is much richer in carbonate 
of lime than the commercial articles, after deduction of sand and 
other accidental impurities. There is no silica in pure bone- 
ash, and it is the silica in the shape of fine sand which, driving 
out carbonic acid from the carbonate of lime, causes the differ- 
ence in the proportion of carbonate of lime found in pure and the 
commercial bone-ash respectively. 
After uniting the lime and magnesia with phosphoric acid, and 
the carbonic acid with lime, it will be seen a considerable quantity 
of lime remains over. I do not think it probable that all this 
lime is present in the shape of fluoride of calcium. 
The state of combination in which it may exist, is of com- 
