59 



Robertson, T. B. ' The Physical Chemistry of the Proteins.' (Longmans. 



Green & Co., 1918.) 

 RoSENBOHM, E. ' The Heat of Swelling of Colloids.' ' Kolloidchem. Beihefte,' 



6, 177 (1914). The swelling of gelatin appears to be divided into two phases, 



the first where a small amount of water is taken up and all the heat of 



swelling is evident, and the second "where a large amount of water is taken 



up and no heat evolved. 

 ToLMAK, R.C., and Steakn, A.E . ' The Molecular Mechanism of Colloidal 



Behaviour.' I. Tlie swelling of Fibrin in Acids. ' J. Am. Cliem. Soc, 40, 



264 (1918). 



Wilson, J. A. ' Retardation by Sugars of Diffusion of Acids in Gtels.' ' J. Ams 

 Chem. Soc' 41, 358 (1919). A reply to the statement by E. A. and H. T. 

 Graham (see above) that Procter's theory cannot account for the repression 

 of the swelling of acid-swoUen gelatin by sugar. 



Wilson, J. A., and Wilson, W. H. ' Colloidal Phenomena and the Adsorption 

 Formula.' 'J. Am. Chem. Soc' 40, 880 (1918). A further mathematical 

 development of Procter's theory of the swelling of colloid jeUies and its 

 relation to other branches of colloid chemistry. 



Wolff, L. K., and Buchner, E. H. ' The Behaviour of Jellies towards Liquid, 

 and their Vapours.' ' Verslag. K. Akad. Wetenschappen,' 21, 988 (1912) 

 and 23, 1323 (1914). It is contended that von Schroeder's observation 

 that the amoimt of water in gelatin swollen in liquid water decreases when 

 the gelatin is placed in water vapour rests upon a defective method of 

 experimentation. 



IMBIBITION OF GELS. PART II.— INDUSTRIAL 

 APPLICATIONS. 



By John Abthuk Wilson, Chief Chemist, A. F. Gallun ds Sons Co., 



Milwaukee. 



Imbibition plays a most important role in the manufacture of 

 leather, paper, textiles, and many other colloidal products, but few 

 cases are generally known of ajjplications of theory to manufacturing 

 conditions. In view of the fact that Procter's theory grew from 

 an investigation of the process of pickling hides, it is not surprising 

 that what applications of it have so far been published have been 

 connected with the leather industry, especially since many of the 

 formulas are of recent derivation. A general survey of applications, 

 to the leather industry has been given by Procter in the First Report 

 pp. 5-20, and need not be repeated here. Wilson and Kern used 

 the theory to explain causes for certain discrepancies in tannin 

 analyses made by the hide-powder method, which is widely employed 

 both in Europe and America. One direct outcome of the theory of 

 imbibition is the Procter-Wilson theory of vegetable tanning, which 

 like its parent theory is largely mathematical in character. The 

 equations forming part of the theory enable one to regulate the 

 astringency of the tannins, their rate of diffusion into the hide, and 

 the degree of plumping of the hide fibres, by simple alterations of the 

 concentrations of electrolytes in the tan Uquors. 



Bovard, in pointing out the importance of imbibition to the 

 manufacture of paper, claims that the character of the sheet is largely 

 determined by the degree of hydration and length of the fibres. He 

 noted that cellulose swells more rapidly in alkaline than in neutral 

 or acid solutions, and since the rosin size used in paper manufacture 

 is alkaline, he reasoned that the hydration of the stock would be 



