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BOOKBINDING 



155 



fectly free from moisture, it is to be separated into small pieces, and sifted through a 

 sieve, the wire or meshes of which are placed at distances of about two and a halt' in 

 every inch. This sifting will not only divide the charcoal into small pieces, but will 

 cause any bits of wood or other improper matters to be separated from it. 



The charcoal thus prepared is then to be packed lightly in cylindrical vessels 

 called crucibles, with some small quantity of bones, oil, or other animal matter, mixed 

 with it. The crucibles are then closed by covers, and luted at the joints, leaving no 

 other opening but one small hole in the centre of the cover, through which any gas 

 generated within the vessel when placed in the oven or furnace may be allowed to 

 escape. 



The crucibles are now to bo ranged round the oven, and placed one upon another, 

 in vertical positions ; and when the oven is properly heated, gas will be generated 

 within each crucible, and issue out from the central hole. The gas thus emitted, 

 being of an inflammable quality, will take fire, and assist in heating the crucibles; 

 and the operation being carried on until the crucibles become of a red heat, the oven 

 is then to bo closed, and allowed to cool ; after which the crucibles are to bo removed, 

 when the charcoal will be found to have become perfectly renovated, and as fit for use 

 as before. 



A process for the restoration of bone-black, or animal charcoal, was made the 

 subject of a patent by Messrs. Bancroft and Maclnnes of Liverpool, which consists in 



washing the granular charcoal, 

 or digesting it, when finely ground, 

 with a weak solution of potash or 

 soda, of specific gravity 1 '06. The 

 bone-black, which has been used 

 in sugar-refining, may bo thus 

 restored, but it should be first 

 cleared from all the soluble filth 

 by means of water. 



Mr. F. Parker's method, patented 

 in June, 1839, for effecting a like 

 purpose, is by a fresh calcination, 

 as follows : 



Fig. 155 represents a front sec- 

 tion of the furnace and retort ; 

 and fig. 156 a transverse vertical 

 section of the same, a is a retort, 

 surrounded by the flues of the fur- 

 nace b ; c is a hopper or chamber, 

 to which a constant fresh supply 

 of the black is furnished, as the 

 preceding portion has been with- 

 drawn from the lower part of a. 

 d is the cooling vessel, which is 

 connected to the lower part of the 

 retort a by a sand-joint c. The 

 cooler d is made of thin sheet-iron, and is large ; its bottom is closed with a slide- 

 plate,/. The black, after passing slowly through the retort a into the vessel d, gets 

 so much cooled by the time it reaches ./', that a portion of it may be safely with- 

 drawn, so as to allow more to fall progressively down ; g is the charcoal-meter, with 

 a slide door. H.M.N. 



BONE-EARTH. The residue of bones after calcination ; it is chiefly phosphate 

 of lime. It finds many uses in the arts. 



BONE-IilQTJOR. The liquor obtained by distilling bones. It is an impure 

 solution of ammonia a poor spirit of hartshorn. 

 BONE-OIL. See DIPPKL'S OIL. 



BOOKBINDING ' in all its branches ' includes every process by which the sheets 

 as received from the printer (from the pamphlet of a few pages to the folio of enormous 

 size and thickness) are arranged in duo order, and the leaves of which each sheet is 

 composed secured and prepared, either simply or elaborately, for the use of the 

 reader. It thus includes every gradation of style and finish, from the stitched and 

 wrappered periodical to the costly and elaborate binding of the most magnificent 

 library. 



The sheets of paper on which books are printed are of various dimensions, beginning 

 with the 'pott' and 'foolscap' (the smallest sizes that come from the paper-maker) 

 up to the 'crown,' 'demy,' 'royal,' 'imperial,' ' atlas,' &c. The printer arranges each 

 of bis pages eo as to occupy, with the required margin, tho half, the fourth, tho 



