BONE BLACK.

159

M. Derosnes proposed to employ animal charcoal in the purification of sirups andsugar refining. The quantities of bone blade left in the retorts employed by MM.Payen. for producing crude carbonate of ammonia, furnished abundant materials forWaking the most satisfactory experiments, and enabled these gentlemen soon to ob-Win ten per cent, more of refined sugar from the raw article than had been formerlyextracted, and to improve, at the same time, the characters of the lumps, bastards,treacle, &c.

The calcination of bones is effected by two different systems of apparatus; by heatingthem in a retort similar to that in which coal is decomposed in the gas works, or inswall pots piled up in a kiln. For the description of the former, see Gas-Light .On the second plan, the bones, broken into pieces, are put into small cast-iron potsthe form shown in fig. 135, about three eighths of an inch thick, two of which aredexterously placed with their mouths in contact, and then luted together with loam.Phe lip of the upper pot is made to slip inside of the under one. These double vessels,c °ntaining together about fifty pounds of bones, are arranged alongside, and over each°™er, in an oven, like a potter’s kiln, till it be filled. The oven or kiln may be either°ulong or upright. The latter is represented in figs. 136, 137, 138. a is the fireplacegrate for the fuel; c c are the openings in the dome of the furnace through whichflame flows; tile divisions of these orifices are shown in fig. 138. n is the wall ofrtek-work. d the space in which tiie pots are distributed. E is the door by which theWkman carries in the pots, which is afterwards built up with fire-bricks, and plasteredth 6r loam. This door is seen in fig. 136. r r are the lateral flues for conveyinge disengaged gases into the air.

135

i on '■ i f

ealci n ;"n„ ? IS a longitudinal section, and fig. 140, a ground plan of a horizontal kiln foris separat ”, nes ' a i s the fire-chamber, lying upon a level with the sole of the kiln; itrows of hi ^ a Pillar b, from the calcining hearth c. In the pillar or wall, severalfor the ea°* eS are at different heights; e is the entrance door; /, the outlet ventsluting thp Se ,i’ Y a P° rs ; and smoke, into the chimney g; h, a sliding damper-plate for regu-By thi s ^mission of the air into the fire in the space a.off with t} l arran “ emen t the offensive emanations are partly consumed, and partly carriedthrough „ e sm oke. To destroy the smell completely, the smoke should be made to pass

■ numh Wnd sma11 furnace ‘

Its d'mensir, r P°. ts that may be put into a kiln of this kind depends, of course, upon

at once ; the ? ’ general, from 100 to 150 are piled up over each other, in columns,

respects th„.® reatest heat being nearest the roof of the kiln; which resembles, in manyIn both k'l USed f ° r .Uniting pottery ware.

h er cest heat 1 ' 1 * 8 ttle ! rUer i° r walls are built of fire-bricks. In the oblong one, the“ntaining th 1S , near the vaulted roof; in the upright one, near the sole; and the pots,ormer, anc j ® larger lumps of bones, should be placed accordingly near the top of theP° ts , c ontaini n 6 . ottom °f the latter. Such a kiln may receive about seventy doublean v er the th l -' le w h°fe thirty-five cwt. of bones.

Pplied at f( rs , r * l ' s filled with the pots, and the entrance door is shut, the fire is®at, for °derately, but afterwards it must be raised and maintained, at a brisk

h 0 ar 'y nlosed to f t * 10urs ‘ The door of the ash-pit and the damper may now beUr s i onge/ moderate the draught, and to keep up a steady ignition for six or eighttak furnace wnflfl’tional firing; after which the doors must be all opened top r . e ? fl°wn the ln'i aen l ^' s * s done, the brick-work of the entrance door must bein .T 10l,s ly filled with 1 ^ nust A® e mptied, and immediately filled again with a set of potse course of a short 0 ?- 68 ’ an< ^ l utei l together; the pots which have been ignited may,time, be opened, and the contents put into the magazine. But