98 THE farmers' handbook. 



To prepare the superphosphate from bone-ash, it is necessary to provide a 

 receptacle for mixing the ingredients which is not attacked by sulphuric 

 acid. A wooden trough lined with lead (a sheet of lead hammered to fit the 

 trough) is about the best ; but a wooden trough, pitched inside, will answer 

 the purpose, ur a hole in the ground lined with cement. In this receptacle 

 the ingredients are mixed in the following proportions: — For every 40 1b. 

 of bone-ash add 1 gallon of water and 15 lb. strong sulphuric acid 

 (commercial oil of vitriol). Pour the whole of the water into the empty 

 tank, then add gradually, stirring; constantly with a wooden Dole, the 

 sulphuric acid. The acid combines very violently with the water, and unless 

 it be added as directed above, an explosion may result. Now add gradually, 

 a little at a time, the bone-ash, stirring constantly with a stout pole or hoe. 



The above proportions should yield a mass possessing the consistency of a 

 stiff dough. If it is not stiff enough, some more bone-ash may be added. 

 Leave it to itself for a few hours, Avhen it will dry to a friable mass, easily 

 broken, and in a fine state of division. Protect from rain whilst drying. 

 The manure is now ready for use. The acid does not actually dissolve the 

 bone-ash, and the resulting superphosphate is very similar in appearance to the 

 original bone-ash, nor is it visibly soluble in water, that is, a large quantity 

 of sulphate of lime is formed which is insoluble. The resulting superphos- 

 phate is acid in character. Although burning the bones destroys the organic 

 matter and diminishes the proportion of nitrogen, this loss is more than 

 compensated for by the ease with which the product can be dried and 

 handled. If fresh bones or bone-meal be used, the fat which they contain 

 prevents the complete action of the acid, and the resulting product is so- 

 slimy as to be unmanageable in many cases, and much difficulty will be 

 experienced in getting it to run through the drill. 



If it is preferred to use fresh bones or meal, the following proportions are 

 said to be the best : — 



Dilute every \ gallon of acid with 1 gallon of water as directed above — 

 that is, add the acid to the water, stirring all the time. Never, on any 

 account, add water to the strong acid. Pour this diluted acid upon 20 lb. of 

 the bone-meal in the trough, taking care to pour slowly, stirring all the 

 while. The sticky mass must now be mixed with loam, wood-ashes, peat, or 

 gypsum, in order to dry it. 



Instead of burning the bones, the oil may be removed by steaming them r 

 but this is rather a troublesome process, though a smaller proportion of 

 nitrogen is lost by this means. Simple boiling with water is better than 

 nothing, but in no case is the product so satisfactory as that piepared from, 

 burnt bones. 



In order to avoid disappointment, it must be remembered that superphos- 

 phate is not entirely soluble in water. It is known as soluble phosphate, 

 but the solubility only refers to the phosphate of lime. A large proportion 

 consists of sulphate of lime (gypsum) produced by the action of the sulphuric 

 acid on the bonedust, and this is insoluble in water. Further, it is an acid 

 manure— that is, it turns blue litmus paper red. 



Instead of using acid, bones may be rendered soluble by allowing them, 

 to ferment (see page 95). The following is also a good plan : — 



Dig a trench, and fill it with alternate layers of wood ashes and bones,, 

 beginning and ending with wood-ashes. Moisten each layer of ashes when 

 laid, and keep the whole moist by watering from time to time. In a few- 

 months the heap may be turned over. 



