Compound Celluloses 99 



Furfural-yielding Complex. 1 It has been found, so far, 

 impossible to isolate this constituent of the fibre-substance ; in 

 the mean time, we are limited to indirect methods of arriving at 

 its constitution and its quantitative relationship to the ligno- 

 cellulose molecule. It has been established, by the elaborate 

 researches of Tollens and his pupils, that the condensation to 

 furfural of those carbohydrates which, from their constitution or 

 configuration, readily yield this special product of dehydration, 

 admits of such control that the yield of the aldehyde may be 

 regarded as constant, and an exact measure, therefore, of the 

 parent molecule. The general method of conversion is that of 

 boiling the substance with hydrochloric acid of 1*06 sp.gr. (12 

 p.ct. HC1). For the estimation of the resulting furfural, various 

 methods have been proposed and practised ; the final selection 

 resting with that which consists in converting the aldehyde 

 into its hydrazone, which is then gravimetrically estimated. 



A careful survey of the evidence upon which this selection 

 is grounded, together with an elaborate account in detail of the 

 methods both of the conversion of the carbohydrate into the 

 aldehyde in question, and its estimation as described, will be 

 found in a recent paper by Flint and Tollens (Landw. Vers.- 

 Stat. 42, 381-407), which should be closely studied. 



The process may be outlined as follows : (a) The weighed 

 fibre (5 grms.) is placed in a flask, covered with 100 c.c. of 

 hydrochloric acid of ro6 sp.gr. The flask is fitted with a 

 double-bored indiarubber cork, carrying (i) the connection 

 to the condenser, the usual bent glass tube, (2) the tubulus 

 of a stoppered * separating funnel.' The flask is heated, 

 preferably in a bath of oil or fusible metal, so that the rate of 

 distillation is about 2 c.c. per minute. The distillate is col- 



The designation 'furfural-yielding complex' or carbohydrate may be 

 conveniently shortened to furfiirose or furfurosan in accordance with the 

 modern nomenclature of the group. 



