130 FARMfcRS' AND MECHANICS' JOURNAL. 



have had to replace three times, once with walnut, once with white 

 ash, and once with red ash. The maple is perfectly sound now. 

 Many reasons may be offered why September is the best time for 

 the felling of timber, but one general reason must suffice for this 

 time : The timber is more ripe in September than at any other 

 time. I have thought that making these suggestions at this time, 

 might induce some to try the experiment this season of removing 

 the bark from trees designed for timber." 



ANIMAL CHARCOJ^L. 



Animal charcoal is prepared from the bones procured in large 

 cities, and particularly at Paris, [France,] where the consump- 

 tion of meat is very great. A great number of persons collect 

 bones throughout large cities, among the refuse of other substances ; 

 and also the bones from kitchens, which are thrown into the streets. 

 Shopkeepers, such as the dealers in marine stores for instance, buy 

 them, and send them to the melters ; who, after having extracted 

 the fat or grease from the bones, sell them to the manufacturers of 

 ivory-black and sal-ammoniac. These boiled bones require to be 

 heated in close vessels ; which operation is performed by two dif- 

 ferent processes. With the bones, broken to pieces, they fill large 

 iron cylinders placed horizontally in a furnace ; which are adapt- 

 ed, by means of a tube of three inches in diameter, with a long 

 range of a refrigeratory apparatus. 



The temperature is gradually raised, till the vessels become of 

 a cherry-red heat ; at which they are kept for thirty-six hours ; 

 when the charcoal is withdrawn from the cylinders, to be instantly 

 enclosed in the extinguishing boxes. It is sufficient, then, to leave 

 it to cool, and to reduce it into very tine powder. The greater 

 part of the animal black is prepared in this manner. 



The secand process consists in carbonizing the bones in cast- 

 iron pots, used in pairs, the one being inverted upon another; so 

 that they assume nearly the form of a cylinder terminated by spheri- 

 cal ends. The joints are luted with loam. The cracks, caused 

 by the contraction which the loam experiences in the fire, are suf- 

 ficient for the escape of the vaporized water, the empyreumatic 

 oil, and the gases resulting from the decomposition of the animal 

 matters ; such as, hydrogen, carbonic-acid, oxygen, and azote, 

 either separate or combined, two and two, three and three, or ia 

 other varied mixtures, during the different periods of operation. 

 The temperature of the whole soon becomes sufficiently elevated 

 for the disengaged volatile products to be inflamed, and thus to 

 assist the operation, by uniting with the fuel to produce heat. 

 When the carbonization is complete, and all the volatile products 

 are disengaged, the furnace is allowed to cool, so that a man may 

 enter it : the brick- work door of the furnace is then broken down, 

 and the cast-iron vessels are emptied : the bone charcoal they 

 contained, is pounded, in the dry state, and is then ready for sale. 



