BONE-DUST AXI) SUPERPUOSl'HATE OK LIMi:. .'U9 



furriisli the two atoms of water for the ph<jsphate, and the two 

 atoms for the sulphate of lime." 



"Such is unciouliteclly the case," said I, "and when large quan- 

 tities of superphosi)hate are made, and the mixing is done by ma- 

 chinery, it is not necessary to use water. The advantage of using 

 water is in tlie greater ease of mixing." 



" Bone-dust," said the Doctor, "contains alioul G per cent of 

 water, and the suli)huric acid (sp. g. 1.7) contains about one-third 

 its weigiit of water. So tliat, if you take 620 lbs. of bone-dust, 

 and mix with it 240 lbs. of common suliihuric acid, you have in 

 the mixture 117 lbs. of water, which is 45 lbs. more than is needed 

 to furnisii the water of coml)iiiati()n." 



"The superph()si)hate produced from 020 llis. of bones, there- 

 fore," continued the Doctor, "would contain: 



Phosphoric acid ) (142 lbs. 



Limu J- acid phosphate -{ 50 " 



Water ) I :«". " 



Sulphuric acid | I KX) lbs. 



Lime J- sulphate of lime ^ 112 " 



Water J ■ { '^> " 



Organic matter, ash, etc., of the bonc6* 3:3."> " 



Total dri/ superphosphate 877 " 



Moisture, or lo>s 45 " 



Total mixture 92^ lbs. 



• ConUinins iiilro^^eii, 2.!', Itis. 



"There is a small quantity of carbonate of lime in the bones," 

 Baid I, "which would take up a little of tiic acid, and you will 

 have a remarkably good article if you calculate that the 020 lbs. of 

 bone-dust furnish you half a ton (1,000 lbs.) of superphosphate. It 

 will be a better article than it is practically jjossible to make." 



" Assuming that it made half a ton," said the Doctor, " it would 

 contain 14} per cent of soluble piiosphoric acid, and 2^^ per cent 

 of nitrogen." 



"With nitrogen at 20 cents per lb., and soluble phosphoric 

 acid at 12ic. per lb., this half ton of superphosphate, made from 

 620 lbs. of good bone-dust, would be worth $22.50, or $45 per ton." 



" Or, to look at it in another light," continued the Doctor, " a 

 ton of bone-dust, made into such a superphosphate as we are talk- 

 ing about, would be worth $72.58." 



" How much," asked the Deacon, " would a ton of the bone-dust 

 be considered worth before it was converted into superphosphate ? " 



"A ton of bone-dusl," replied the Doctor, " contains 76 lbs. of 

 nitrogen, worth, at 18 cents per lb., $13.68, and 404 lbs. phosphoric 

 acid, worth 7 cents per 11>., $32.48. In other words, a ton of bone- 

 dust, at the usual eslimatJ, ii worth $46.16." 



