MANUFACTUEE OF BONE SUPEEPHOSPHATE. 175 



waste such as debris of skins, gut, etc. It is impossible to give a 

 complete analysis, seeing the difficult}^ of taking a fair average sample. 

 The skill and experience of the buyer, and inspection by a glance 

 of his eye, are the best guides. Fossil bones naturally ditfer in 

 their composition, thus their fluorine content rises to as much as 

 16 per cent. Miiller found 17 per cent of gelatine in diluvian 

 bones. 



Fertilizing Value of Bones. — The use of bones as a manure has 

 been known for a long time. They have been used for centuries 

 in the manuring of vines in the south of France. Hunter, in 

 Endand, drew the attention of farmers to bones in 1771. In that 

 country the use of bones doubled and trebled the production of 

 mediocre land, at a time when certain continental agronomists were 

 still protesting against what they called the spoliation {gaspillage) 

 by the bones used in fertilizing the land. England knew how to 

 profit adroitly by this situation, by importing thousands of tons of 

 bone 3 at a vile price. At a certain time all the production of bones 

 took the road to Great Britain, although it had itself an enormous 

 production, and in spite of a rise in freights. In 182:^, the battle- 

 fields of Central Europe, in themselves alone, furnished her with 

 33,000 tons. 



But the introduction of Persian guano, the pioneer of all other 

 concentrated manures, completely altered the situation. There is 

 not now to be found a single farmer who does give to bone 

 manures all the credit which they deserve, even when he is in- 

 different to other manures. However, uncrushed raw bones are 

 absolutely valueless to the farmer, as they do not become soluble 

 in the soil until after a very long time. Now, in order to obtain 

 good crops, the farmer requires rapid decomposition of the nitro- 

 genous matter and of the phosphate in the soil. The bones must 

 therefore undergo an appropriate operation. In chemical manure 

 factories it is reduced to a fine powder or the gelatine is extracted 

 from it, and it is afterwards made into superphosphate (dissolved 

 bones). The use of bones in any other form is spoliation. Bone 

 waste (fleshy fibre), which can be often bought cheap, should be 

 similarly treated. 



Storing, Classifying, Sorting and Crushing Bones. — Storing. — 

 The first duty of the manufacturer is to bring all his care to bear 

 on the storing of bones, because when they begin to rot they give 

 off a smell which the workmen cannot stand. Besides, the decom- 

 position of nitrogenous matter gives rise to a disengagement of 

 ammonia, and there is a loss of nitrogen which may exceed 0"5 per 

 cent. The drying of fresh bones requires fastidious and costly 

 manipulations ; that is why they rest content with sprinkling them 

 with water containing O'Oo percent of carbolic acid or with spirits 

 of turpentine. 



