176 CHEMICAL MANUEES. 



Classification of Bones. — Market bones are classified as fol- 

 lows : — 



(1) Kitchen Bones. — These consist of ox, calf, sheep, goat, and 

 some game bones. They are fresh, dry or fused (fttse, ? roasted). 

 They often contain 20 to 25 per cent of water. Dry bones are called 

 country bones. Their percentage of moisture is from 8 to 12 per 

 cent. Thev are generally crushed and often fat -extracted by the 

 vendors, which is readily recognized by the farinaceous tint of the 

 bones on the outside. Fused bones enter into the class of the fossil 

 bones ; they are unfit for glue- making, for the organic matter has in 

 great part disappeared owing to fermentation and exposure to all 

 sorts of weather. Amongst kitchen bones are to be found sheep 

 bones and those of kids, with down, and pork bones, which are less 

 esteemed. Kitchen bones generally contain remains of horns, horn- 

 piths, glass, scrap iron, earth, bread. Hand picking enables the 

 value of the goods to be appreciated. 



(2) Horse Bones or Knackers' Bones. — These bones yield a less 

 valuable glue than kitchen bones, and they have to be sold cheaper. 

 Ten per cent of these bones are tolerated amongst kitchen bones.. 

 The fat and glue which they yield are inferior. 



(3) Buried Bones. — Buried bones are those of animals (ox, horse) 

 w^hich have remained a certain time in the ground to destroy the 

 flesh. They are the bones of infected animals which have taken a. 

 bistre colour owang to burial. They are depreciated and the manu- 

 facturer refuses those with hanging flesh.i 



(4) Bullocks' Heads and Canards {Sheep's -Heads) pass into 

 the kitchen bone class, but they are generally sold apart for the 

 acidulator (? glue maker,? manure maker : both are acidulators). 



(5) Scraps and Waste.— These are the residues of the " turnery " 

 trade. They are in great request for acidulation and are sold 



separatelv. 



(6) Hornpiths.— They are used like "scraps" for acidulation. 

 Thev are fresh or drv. The dry piths are often fused and are then 



of less value. 



Bones, therefore, in consequence of the different material which 

 they contain, are classed and assorted so that the operations which 

 they have to undergo furnish satisfactory products. As the bones 

 are most often mixed with impurities which are of a nature to 

 damage the machines, it is necessary to pick or assort them. 



Bone Picking. — In factories of a certain size the picking is done 

 on shaking tables, driven mechanically or by means of large sifting 

 machines, both appliances being fitted with meshes of % of an inch. 

 Soil and small particles of bone fall through the grating, whilst 



1 The resurrection of the bones of infected animals is a most dangerous 

 practice. The earth mould from the remains of animals dead of anthrax is 

 Btill infectious after twenty years.— Tr. 



