The Typical Cellulose and the Cellulose Group 55 



Although, therefore, the products resulting from the action 

 of hydrochloric and sulphuric acids (1*55 sp.gr.) are identical 

 in empirical composition, they are the very opposite in physical 

 characteristics, and the actions of these acids certainly take 

 very different courses. 



It should be noted that the action of sulphuric acid at 

 greater dilution (1-3 sp.gr.) approximates closely to that of 

 hydrochloric acid, the product being a disintegrated and 

 friable mass of the hydracellulose. 



The non-oxidising acids generally produce similar results, the 

 degree of action being proportionate to their hydrolytic activity. 



A curious practical application of these processes of disin- 

 tegrating cellulosic tissues may be noted in evidence of the 

 fundamental chemical distinction of the vegetable (cellulose) fibres 

 from those of animal origin (silk and wool). The latter are very 

 resistant to the action of acids. From a wool-cotton fabric, there- 

 fore, the cotton is easily separated by soaking the fabric in dilute 

 sulphuric acid, and, after removing the excess of acid, drying down 

 on a hot floor. The disintegrated cellulose is then completely 

 removed by dusting out, leaving the wool unaffected. A similar 

 result is obtained with hydrochloric acid ; or by treatment with 

 certain chlorides which are dissociated, on heating, into hydrochloric 

 acid and basic oxide e.g. aluminium chloride or chlorhydrate. 



On the other hand, the animal fibre-substances are extremely 

 sensitive to the action of alkalis, to which, as we have seen, the 

 celluloses are very resistant. The student should compare the 

 constitution of the substances in question, so far as they have been 

 elucidated, with that of cellulose, and for that purpose should read 

 Bed. Ber. 1886, 850 ; J. Soc. Chem. Ind. 12, 426. 



This activity being conspicuously feeble in the case of acetic 

 acid, this acid has but little action upon cellulose, and therefore 

 finds extensive use in the printing of cotton and linen fabrics. 



Solutions of the mineral acids are extensively used in the 

 'souring' operations of the bleacher and dyer. They are 

 usually employed cold, and the operation of souring is always 



