140 A VISIT TO A BONE BOILING FACTORY. 



closed bins or receptacles, some in carts, and others in piles on the 

 ground. On inquiring their uses, and the cause of the separation, we 

 are informed that the very best are converted into animal charcoal, 

 which is the chief product of the establishment, the large marrow bones 

 are sent to France, and the thin bones are used for making knife, tooth 

 brush, and other handles ; the ends of the bones are cut off by a steam 

 saw, and used for ■ buttons, small toys, &c. The bones are carefully 

 selected into heaps, and each kind is boiled separately in open pans by 

 steam at a low temperature, or not more than 212°. Marrow bones 

 take from 1^ to 2 hours ; common bones, such as blade bones, small 

 bones, &c, from 3 to 9 hours ; and the ends of the marrow and other 

 bones require 10 hours to boil. The fat, wbich is white from fresh 

 bones, and brown from old bones, is skimmed off, and as the pans are 

 hung on an axis, the contents are emptied at pleasure into a truck on 

 wheels beneath. Tbe bones are then allowed to drain, and are trans- 

 mitted to their required places. 



When bones are submitted to destructive distillation, the gelatine 

 and albumen which they contain is abundantly productive of ammonia ; 

 hence a copious source of that alkali and its compounds ; the residue is 

 a mixture of the earthy part of the bone with charcoal, commonly 

 termed bone black. 



Bone black possesses the extraordinary property of appropriating to 

 itself the colouring matter of near ly all fluids that are filtered through 

 it, and so powerful is its agency in this respect, that in testing the 

 quality of some bone black offered for sale, a dark coloured claret was 

 so completely discoloured in a single filtration, through a depth of 

 twelve inches of the black, as to be undistinguishable by the eye from 

 the purest spring water. The introduction of this powerful auxiliary 

 has created a complete revolution in the process of manufacturing and 

 refining beet sugar on the Continent, and cane sugar in the sugar 

 colonies of the East and West Indies. The only drawback to its use 

 was its cost, because formerly it was thrown away. as soon as repeated 

 nitrations had saturated the black with the colouring matter and im- 

 purities of the syrup, to such an extent as to deprive it of its efficacy ; 

 but the discovery of a mode of renovating, or as it is technically termed, 

 " revivifying? the bone-black has obviated this difficulty, by causing 

 the manufacturer to use the same charcoal for an indefinite length of 

 time with but little loss in quantity or quality. The process of revivi- 

 fication is simple and inexpensive. 



Messrs. Leblay and Cuisinier have published a new process for 

 reviving exhausted charcoal. They find that the power of absorbing 

 colouring matter is restored on treating the charcoal with a weak boil- 

 ing solution of caustic alkalies. They also state that the original absorb- 

 ing power maj* be very much increased by pouring over it a weak 

 solution of sulphate of lime. 



If (say? Mr. A. Aikin,) we throw into the fire a bone, even of the 



