SUPERPHOSPHATE OF LIME. 261 



Alkaline sulphates and 



chlorides, . . 0.82 .... 0.82 lbs. 



.Free oil of vitriol, . 3.54 .... 3.54" 



100. 34.47 



No account is here taken of the solubility of the sulphate 

 of lime. It is all ultimately soluble in cold water. The 

 actual amount of the crude superphosphate, readily soluble 

 in cold water, is about 40 per cent, of which 5, or -J, is sul- 

 phate of lime. By repeated treatment with cold water, at 

 least one-half of the air-dried superphosphate, as above con- 

 stituted, is dissolved, and in the soil would minister imme- 

 diately to the wants of plants. Ultimately, all the crude 

 superphosphate would dissolve in soil. 



307. Having thus explained the composition of bone in its 

 various forms, and determined the quantity of oil of vitriol 

 which is requisite to convert 100 lbs. to superphosphate, that 

 process is to be conducted as follows, supposing bone ashes 

 to be used: 



Take a half hogshead tub, or any vessel of similar depth, 

 which will hold from 80 to 100 gallons. If lined with lead 

 it is better, but this is not essential for making a few hun- 

 dred pounds. 



1. Put 100 lbs. of burned bones, ground to fine powder, 

 into the tub. 



2. Wet the bone ash with 5| gallons of cold water, mix- 

 ing evenly. 



3. Pour on this wet mass 5J gallons, or 87^ lbs. by weight 

 of best commercial oil of vitriol. 



4. With a stout wooden paddle, stir the whole briskly, so 

 as to mix thoroughly and evenly the materials. The mixture 

 works, froths, and foams, becomes nearly boiling hot, steams 



