Compound Celluloses 



169 



that these all contain celhtloses easily hydrolysed by dilute acids 

 to ' glucoses ' thus clearly anticipating the later work upon the 

 celluloses of Class C (p. 85) the author makes the following 

 statement in regard to the cereal straws : 



' L'exemple le plus frappant de cet effet nous est oflfert par la 

 paille, dans laquelle le microscope ne nous fait decouvrir aucune 

 trace d'amidon et dans laquelle pourtant on dose d'apres les 

 methodes ci-dessus indiquees 20 p.ct. d'amidon ' : the method 

 consisting in hydrolysing with dilute sulphuric acid (2 p.ct H.,SO 4 ) 

 at 108, and titrating, in alkaline solution, with Fehling's solution 

 as in glucose estimations. Celluloses thus easily hydrolysed may 

 be assumed also to be digestible by the animal organism, and to 

 have a value equal to that of starch. In the case of starchy fodders, 

 however, the author adds to his scheme a method for the exclusive 

 estimation of starch, and selects the process of diastatic conversion. 

 In determining crude fibre (described in the original as * cellulose 

 brute') the method of alternate digestion (at 108) with dilute acid 

 (2 p.ct. H 2 SO 4 ) and alkali (5 p.ct. KOH) was adopted. The residues 

 from these treatments were found to have the composition, and 

 to be formed in the proportions, given in the annexed table : 



the high C percentage being referred to the * ligntn* group remain- 

 ing in combination with the cellulose. The proportion of nitrogen 

 in these residues surviving the treatment is from 0-2 to 0-3 p.ct. 

 which is neglected in the calculations. In criticising this process 

 the author clearly states that it is of purely statistical and approxi- 

 mate value, even as a measure of non-digestible constituents ; and 

 as a determination of cellulose, valueless, if not altogether mis- 

 leading. 



Having found in effect that from 20-25 P- ct - of the substance of 

 straws yields to acid hydrolysis in the same way as starch, and 

 that the constituent so attacked appeared to be of the nature of 

 cellulose, the following method is proposed for estimating the 



