“Such is undoubtedly the case,” said I, “and when large quantities of superphosphate are made, and the mixing is done by machinery, it is not necessary to use water. The advantage of using water is in the greater ease of mixing.”
“Bone-dust,” said the Doctor, “contains about 6 per cent of water, and the sulphuric acid (sp. g. 1.7) contains about one-third its weight of water. So that, if you take 620 lbs. of bone-dust, and mix with it 240 lbs. of common sulphuric acid, you have in the mixture 117 lbs. of water, which is 45 lbs. more than is needed to furnish the water of combination.”
“The superphosphate produced from 620 lbs. of bones, therefore,” continued the Doctor, “would contain:
| Phosphoric acid | acid phosphate | 142 lbs. |
| Lime | 56 lbs. | |
| Water | 36 lbs. | |
| Sulphuric acid | sulphate of lime | 160 lbs. |
| Lime | 112 lbs. | |
| Water | 36 lbs. | |
| Organic matter, ash, etc., of the bones* | 335 lbs. | |
| Total dry superphosphate | 877 lbs. | |
| Moisture, or loss | 45 lbs. | |
| Total mixture | 922 lbs. | |
* Containing nitrogen, 23½ lbs.
“There is a small quantity of carbonate of lime in the bones,” said I, “which would take up a little of the acid, and you will have a remarkably good article if you calculate that the 620 lbs. of bone-dust furnish you half a ton (1,000 lbs.) of superphosphate. It will be a better article than it is practically possible to make.”
“Assuming that it made half a ton,” said the Doctor, “it would contain 14¼ per cent of soluble phosphoric acid, and 2⅓ per cent of nitrogen.”
“With nitrogen at 20 cents per lb., and soluble phosphoric acid at 12½ c. 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 talking 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?”