68 Cellulose 



D. DECOMPOSITION BY HEAT. DESTRUCTIVE DISTILLA 

 TION. Destructive distillations of cellulosic raw materials con- 

 stitute an extremely important group of industrial processes ; and 

 if we include the coals in such a classification, the hydrocarbons 

 of coal tar must be regarded as products of a series of trans- 

 formations of cellulose, of which the final stages are determined 

 by destructive distillation. By the direct action of heat, 

 however, upon the celluloses proper, 'aromatic' products 

 hydrocarbons and phenols are obtained in relatively small 

 quantity. The main products are (i) gases : carbonic 

 anhydride, carbonic oxide, and methane ; (2) liquids : water, 

 acetic acid and furfural, methyl alcohol, and small quantities of 

 hydrocarbons and phenols ; (3) solids : paraffins and aromatic 

 hydrocarbons in small quantity, and the residual charcoal. 



The proportions of these products necessarily vary with all 

 the conditions of the distillation, chiefly (i) rapidity of heating 

 and (2) maximum temperature attained. Recent investigations, 

 in which these conditions were carefully regulated and the 

 products of distillation estimated, have led to more definite 

 results than those of previous date. It must be borne in mind 

 that the term Cellulose has been used in a somewhat loose way, 

 and by some writers or compilers of articles as synonymous 

 with the cellulosic raw materials generally. * The destructive 

 distillation of cellulose ' has in consequence been described as 

 including the woods. ' It is important now to differentiate 

 between the products obtained from the typical cotton cellulose 

 and compound celluloses, such as the woods. These differences 

 will be noted more particularly when treating of the latter 

 group. At this point we give the results obtained for (a) raw 

 cotton, (b) bleached cotton (Ramsay and Chorley, J. Soc. 

 Chem. Ind. n, 872), and (c) cellulose (cotton) regenerated 

 from solution as thiocarbonate. 



