260 THE SOUTHERN PLANTER. 



reaction was complete, and the manure 

 had dried as much as it would by expo- 

 sure to air, give a product having about 

 the following composition in 100 parts — 

 Moisture. 10 

 Animal Matter, 2. 

 Sulphate of Lime (Plaster) 39 

 Superphosphate of Lime, 24 

 Equal to 35 per cent of bone phosphate. 



The animal matter would yield from 1 

 to 1| per cent, of ammonia. In this cal- 

 culation we have supposed the transforma- 

 tion to be complete, and all the phosphate 

 to have become soluble ; but in practice 

 this is ne-ver the case, a^ more or less of 

 the bone dust will escape the action of the 

 acid, and therefore remain insoluble. 



When this compound is applied to land, 

 and moisture is present, the free phospho- 

 ric acid immediately enters into combina- 

 tion with the bones present, forming neu- 

 tral phosphates which are in an exceed- 

 ingly fine state of division, and more inti- 

 • mately blended with the soil, than they, 

 could be by any other mode of application; 

 while the neutral phosphate which was 

 soluble in consequence of the presence of 

 the free acid, is precipitated in an equally 

 fine state of division, and also intimately 

 mingled with the soil. 



If, instead of allowing the manure to 

 dry up, some foreign substance is added 

 to absorb the water, its value is deprecia- 

 ted in proportion to the quantity of foreign 

 i matter used, unless the addition consists of 



some highly concentrated manure, such as 

 Peruvian guano, the sulphate of ammonia, 

 or dried blood. If the substance added 

 contains any bone, such as oxide of iron, 

 lime, or magnesia, the free phosphoric acid 

 unites with them, the phosphates become 

 insoluble, and there is no longer more than 

 .a very small per cent., if any, of the su- 

 perphosphate of lime — the manure has re- 

 turned to its original condition. 



From what has been said before in rela- 

 tion to precipitated phosphate of lime, it 

 follows that these phosphates, although in- 

 soluble, are far better suited to minister to 

 growing vegetation than the original bone 

 dust, but then the intimate mixture and 

 incorporation of the phosphate with the 

 soil, which results from an application of 

 really soluble phosphate to it, cannot be 

 attained by the use of one which has al- 

 ready been neutralized. But this is not 

 the greatest objection to the use of sub- 



stances which will neutralize the free acid 

 present ; so long as the practice is counte- 

 nanced, so long will frauds be almost un- 

 limited. A farmer purchases what pur- 

 ports to be a true superphosphate of lime, 

 he has it examined by a chemist who tells 

 him that it is not superphosphate ; that 

 not one particle of it is soluble, or, at most, 

 but a very small per centage ; and that 

 all the phosphate there is neutral phos- 

 phate. How, I ask, is the farmer to know 

 whether his manure ever was soluble, or 

 contains precipitated phosphate, instead 

 of the original bone phosphate, just as it 

 came from the mill, or from the sugar re- 

 finery ? If the amount of soluble phos- 

 phates is to be no index of the value of the 

 manure, it will be made, (as it sometimes is 

 made,) by deliberately mixing ground plas- 

 ter with finely ground bones. The only way 

 to check fraud, and secure a manure that 

 is worthy the name of superphosphate, is 

 for the purchaser to insist upon there be- 

 ing a certain per centage, and that not a 

 small one of soluble phosphate of lime in 

 every particle purchased. 



Bone black is prepared in large quanti- 

 ties for the use of the sugar refiners, by 

 heating bones in close vessels so as to ex- 

 clude the air ; after repeated using to clar- 

 ify the syrup, it loses its properties, and ' 

 may then be profitably used in the manu- 

 facture of superphosphate of lime. In its 

 preparation the animal matter is all de- 

 composed, and in its stead there is left a 

 certain amount of charcoal. When treat- 

 ed with a proper proportion of sulphuric 

 acid, so as to convert all the neutral into 

 superphosphate of lime, it becomes just 

 as valuable as the superphosphate from 

 unburned bones ; it is true there is no ani- 

 mal matter to yield ammonia, but the in- 

 creased per centage of superphosphate 

 more than compensates for this loss, when 

 we compare the money values of ammonia 

 and superphosphate of lime. Refuse bone 

 black has been found to contain from 6*5 

 to 75 — say 75 per cent, of neutral phos- 

 phate of lime, 10 or 12 of carbonate of 

 lime, and about the same proportion of 

 charcoal. 100 parts, therefore, would re- 

 quire about 12 parts of sulphuric acid to 

 decompose the carbonate, and some 38 

 parts of the same acid to transform the 

 bone into superphosphate of lime ; or the 

 bone black would require about one-half 

 its weight of acid. 



