Tl^p SOUTHERN PLANTER. 



261 



This would give us a manure yielding 

 32 per cent, of soluble or superphosphate 

 of lime in 100 parts, equivalent to 46f 

 per cent, of the neutral phosphate ; and 

 as the proportion of sulphuric acid used 

 was larger, it follows that the proportion 

 of plaster would be considerably greater 

 than in other cases. We see, therefore, 

 how valuable refuse bone black is as a 

 source of manure, even when compared 

 with ground bones, and how groundless is 

 the belief, which is quite prevalent, that 

 bone bj^ick is greatly inferior to ground 

 bones as a source of superphosphate of 

 lime. By using bone black instead of 

 bones, we shall have some 8 per cent, 

 more soluble phosphate in the 100 parts, 

 equivalent to about 12 per cent, of neutral 

 phosphate, together with a material addi- 

 tion to the amount of plaster, which, as I 

 have said before, is more than sufficient to 

 compensate for the loss of If per cent, of 

 ammonia. 



Boiled bones have lost most of their fat 

 and some of their other animal matter, 

 while the proportion of phosphate of lime 

 in them is something greater than in raw 



Do 



bones ; in using them, therefore, as a 

 source of superphosphate of lime, a little 

 more acid is necessary than for common 

 bone dust, and the composition of the ma- 

 nure will be somewhat different; there 

 will be a liUle more soluble phosphate and 

 plaster, and less ammonia. 



Bones that have had all their animal 

 matter burned off in the open fire, are 

 sometimes used; they contain some 80 or 

 90 per cent, of phosphate of lime, and 

 consequently require more acid than is 

 necessary for any other form of bones. 



Mineral phosphate of lime, Mexican and 

 Columbian guano, may all be used for the 

 same purpose ; the quantity of acid, and 

 in each case, should always be determined , 

 by reference to the proportion of neutral 

 phosphate present. 



I have before remarked that the com- 

 plete transformation of the phosphate is 

 not attainable in practice, particularly 

 when the manure is manufactured on a 

 large scale ; yet a reasonable approach 

 ought to be made to the numbers given 

 above. In an experiment made in my 

 laboratory, with bones that were not by 

 any means in as fine a state of division as 

 they should be, I prepared a superphos- 

 phate in which their was 18 per cent, of 



soluble phosphate of lime, equivalent to 

 28 per cent, of neutral phosphates, the en- 

 tire* phosphate present was 35 per cent., 

 so that 7 per cent, of it remained untouch- 

 ed by the sulphuric acid. It also contained 

 the usual amount of animal m.atter capable 

 of yielding ammonia, and the proportion of 

 plaster due to the quantity of sulphuric 

 acid used. Had I added some foreign 

 substance, the proportion of soluble matter 

 would have been less ; suppose, for exam- 

 ple, that 25 per cent, of some other sub- 

 stance had been added, then the propor- 

 tion of soluble phosphates would have 

 been reduced to about 14f per cent. 



Prof. Way, chemist to the Royal Agri- 

 cultural Society of England, after having 

 examined numerous samples of super- 

 phosphate of English manufacture, says, 

 that the farmer has a right to expect from 

 8 to 11 per cent, of soluble phosphate, and 

 from 1 to 1| per cent, of ammonia, in 

 every sample purchased. Now, I think 

 this estimate is too low; I think that the 

 farmer has a right to expect some 16 or 18 

 per cent of soluble phosphate, and from 

 | to If per cent, of ammonia in every 

 sample ; and if the proportion of soluble 

 phosphate is less than this, then he may 

 fairly expect, a proportionate increase in 

 the per centage of ammonia, otherwise he 

 certainly is not getting an equivalent for 

 his money. 



To show this, let us take my own sam- 

 ple, in which the proportion of soluble 

 phosphate was not, I am sure, more than 

 ought to be obtained in practice by any 

 one who is at all conversant with hts bu- 

 siness. This contained. 18 per cent, of 

 soluble phosphate ; the addition of 25 per 

 cenfc of foreign matter would have reduc- 

 ed it to 14f per cent. If this addition had 

 been Peruvian guano, we should have had 

 an increase of about 4 per cent, in our 

 ammonia, and about 7 per cent, in our 

 neutral phosphate; then the manure would 

 have contained 14f per cent, soluble phos- 

 phate of lime, 14 per cent, insoluble or 

 neutral phosphate, about 5 per cent, am- 

 monia, and the proportion of plaster due 

 to the acid used. 



Sulphate of ammonia or dried blood, or 

 a mixture of either of these with guano, 

 would also have been useful additions, be- 

 cause they would have materially increas- 

 ed the per centage of ammonia; but to 

 have added any other substance, such as 



