Experimental and Applied 257 



themselves, more especially in the regions of high temperatures, 

 rendering it somewhat difficult to distinguish the primary from 

 secondaiy products. 



Generally we may take the saturated compounds of lower 

 molecular weight as direct products of the decomposition : these are 

 water, oxides of carbon, methane, methyl alcohol, formic and 

 acetic acids, &c. Volatile compounds, either hydrocarbons or their 

 derivatives, containing unsaturated C H nuclei, result from re- 

 arrangements of the component groups of the original celluloses ; 

 these are olefines and aromatic hydrocarbons, furfural, phenols, 

 aromatic methoxy-derivatives, &c. ; the residue of the process or 

 charcoal represents the extreme limits of condensation of the 

 carbon nuclei. 



One important general feature of the decomposition is notice- 

 able as connecting the decomposition with those determined by 

 electrolysis and fermentation in the case of compounds of similar 

 constitution, that is, the accumulation of hydrogen in the one direc- 

 tion, and oxygen in the other. Thus we have, on the one hand, 

 methane and a large number of compounds containing the CH 3 

 and O.CH S group ; and, on the other, CO and CO 2 . Acetic acid 

 represents an intermediate equilibrium, viz. of CH 4 and CO 2 . We 

 have already seen that the introduction of the alkaline hydrates so 

 alters the character of the decomposition that acetic acid becomes 

 a main product of decomposition ; and the remainder of the re- 

 action consists in the production of the more fully oxidised oxalic 

 acid (with CO 2 ), * balanced,' so to speak, by the formation and 

 liberation of hydrogen. These considerations illustrate the views 

 which may be applied to the elucidation of the very complex pro- 

 blems in dissociation, generally presented by destructive distillation. 



Constitution of Cellulose. Theoretical Notes. It is, perhaps, 

 premature to approach the problem of the constitution of cellulose, 

 as the molecule of cellulose is at present an altogether unknown 

 quantity. It will be instructive to the student to study, for their 

 general bearing on the subject, the investigations which have been 

 devoted to the elucidation of the structure of the starch molecule, 

 notably those of O'Sullivan (J. Chem. Soc. 1872), Brown and 

 Morris (ibid. 1889, 449-462), Lintner and Dull (Berl. Ber. 26, 



2533)- 



These researches are based on the study of the hydrolytic dis- 



S 



