2O Cellulose 



cise knowledge of the first only ; the ' theory of solution ' is a 

 recent development, and the third factor is at present to be dealt 

 with only speculatively ; and of the constitution of the celluloses 

 we have at present only a general knowledge. 



The further investigation of these problems is therefore probably 

 the most promising direction from which to approach the position 

 of the actual molecular constitution of the celluloses. 



The actions of dilute alkaline and acid solutions at higher 

 temperatures are, of course, more pronounced. The mineral 

 acids of concentration, equal to semi-normal at the boiling 

 temperature, rapidly destroy in the sense of disintegrating 

 cellulose fibres, producing an important molecular change in 

 the cellulose itself. The modified cellulose is brittle and 

 pulverulent, and will be more fully described as the product 

 of the action of concentrated hydrochloric acid, viz. as hydro- 

 or hydracellulose. The time required for completing this 

 change varies of course with the temperature and the concen- 

 tration of the acid. The acid treatments of cellulose textiles, 

 which are necessary incidents of bleaching and dyeing opera- 

 tions, are carried out as a result of practical experience well 

 within the limits of safety ; such treatments being for the most 

 part in the cold (<7o F.) and at strengths of 0-5-2-0 p.ct. 

 (HC1,H 2 SO4). In dyeing operations requiring an acid bath 

 and the boiling temperature, ' free ' mineral acids are as much 

 as possible avoided, acetic acid being substituted. This acid 

 is without sensible action on cotton. 



The action of the acids in disintegrating cellulose structures 

 is undoubtedly hydrolytic^ and of the same order, for instance, 

 as their action upon cane sugar. The ' inversion ' of saccha- 

 rose by boiling with the dilute acids is not, it must be remem- 

 bered, a simple process of hydration ; according to the usual 

 equation, 



CiiH M O n + H 2 O = C 6 H 12 O 6 + C 6 H 12 O 6 , 



Dextrose Levulose 



