18 



The gelatine contains from 3 to 5 per cent of nitrogen, and the phos- 

 phate of lime (or bone phosphate) from 18 to 23 per cent of phosphoric 

 acid. Bones are brought to the fertilizer manufacturer as the waste of 

 the slaughter-house or butcher shops. Where they have been exposed 

 to the action of the elements bones are found to have lost more or less 

 of their gelatine, and hence are not so rich in nitrogen. The methods 

 of preparing bones for plant food are numerous. By one method the 

 gelatine is saved, and by the other lost. To make the phosphoric in 

 this fully soluble, the bones must be first treated with sulphuric acid, 

 though the results from burning the bones are to reduce the particles to 

 so fine a state as to make them more or less available without the use 

 of acid. 



BONE MEAL. 



This substance is made by cracking up and grinding dry bones. These 

 contain, as materials valuable for fertilizers, phosphate of lime and cer- 

 tain complex substances containing nitrogen. The phosphate is the 

 chief constituent; it forms the frames of the bones, and is what might 

 be called the mineral portion of the same. The other plant food con- 

 tained in bones belongs to that class of matter from which the plant 

 obtains the material necessary for building the so called albuminoid 

 substance, such as the gluten of wheat, and the legumin of the pea, to 

 which those substances owe their nourishing and flesh-forming qual- 

 ities. The more finely divided a fertilizer is the more valuable it is, on 

 account of the greater readiness with which it goes into solution. Hence, 

 in determining the value of a fertilizer, the mechanical analysis is of 

 considerable assistance. 



MANUFACTURING SUPERPHOSPHATE. 



In the manufacture of superphosphate, Professor Nichols recommends 

 the following plan: Take a plank box four feet square and one foot deep. 

 This may be simply water tight, and if so there must be no nails that 

 the acid can reach, for it will eat them out and so make a leak, or it 

 may be lined with lead, all soldering being done with lead solder. The 

 box will be large enough to take a carboy of sulphuric acid with the 

 necessary quantity of phosphate material and water to make about a 

 quarter of a ton of superphosphate. If finely ground bone be used, 

 the result following will be a pasty mass, needing mixing with muck or 

 other dry material to get it in good mechanical condition for use. If, 

 instead of bone, bone black is used, the result will be a dry mass easily 

 handled. To make superphosphate, a carboy of one hundred and sixty 

 pounds of sulphuric acid or oil of vitriol (60 degrees), three hundred 

 and. eight pounds of bone black, and ten gallons of water are required. 

 Having first donned old clothes, and having at hand a little saleratus 

 or some alkali, ready to rub on any spot should by chance a drop 

 spatter (for where it touches if not immediately neutralized it will char 

 like fire), be sure to first pour in the water, and then the acid; next, 

 slowly add the bone, stirring it all the while with an old hoe of but 

 little value. There will be a great commotion', a great boiling, frothing, 

 and foaming, and throwing off of heat with a suffocating vapor. Because 

 of the suffocating vapor, it is better to do the work in the open air or 

 under an open shed. 



