61 



are identical with those governing the hydration and dehydration of certain 



proteins, which in turn show analogies to living cells. 

 Habrison, W. ' Investigations on the Physical and Cliemical "Properties of 



Cotton. Report of ' The Nat. Assn. of Cotton Mfrs.', 1916. 

 LoEB, Jacques. ' The Mechanism of the Diffusion of Electrolytes through the 



Membranes of Living Cells.' I. The Necessity of a General Salt Effect upor 



the Membrane as a Prerequisite for this Diffusion.' ' J. Biol. Chem.' 27, 



339 (1916). II. The Diffusion of Potassium Chloride out of the Egg of the 



Fimdulus and the Relative Efficiency of Different Ions for the Salt Effect. 



Ibid., 353. III. The Analogy of the Mechanism of the Diffusion for Acids 



and Potassium Salts. Ibid., 363. 



' The Similarity of the Action of Salts upon the Swelling of Animal Mem- 

 branes and of Powdered Colloids. Ibid., 31, 343 (19l'7). 

 Procter, H. R. ' Recent Developments in Leather Chemistry. ' J. Royal 



Soc. Arts,' 1918. 



' CoUoid Chemistry of Tanning. ' First Report,' p. 5. 

 Peocter, H. R., and Burton, D. ' The Swelling of Gfelatinous Tissues.' J. 



Soc. Chem. Ind.' 35, 404 (1916). Treats tlie subject from the viewpoint of 



the leather chemist. 

 Procter, H. R. and Wilson, J. A. Theory of Vegetable Tanning. J. Chem. 



Soc' 109, 1327 (1916). 

 Sheppard, S. E., and Elliott, F. A. ' The Reticulation of Gelatin.' J. Ind. 



and Eng. Chem.' 10, 727 (1918). An application to photography. 

 Tratjbe, L, and Kijhlee, F. ' The Velocity of Formation and Solution and of 



SweUing of Gels.' ' Intern. Z. Biol.' 2, 42 (1915). A discussion is given of the 



relation between experimental results and the following biological problems : 



narcosis, plasmolysis of cells, cheraotaxis, muscular work, edema, and 



inflammations. 

 Tratjbe, L, and Mabusawa, T. ' Swelling and Germination of Plant Seeds.' 



'Intern. Z. Physik. Chem. Biol.' 2, 370 (1915). 

 Upson, F. W., and Calvin, J. W. On the Colloidal Swelling of Wheat Gluten.' 



'J. Am. Chem. Soc' 37, 1295 (1915). 

 Wilson, J. A. ' Theories of Leather Chemistry.' ' J. Am. Leather Chem. 

 .♦Assn.' 12, 108 (1917). 



'Theory of Tanning,' ibid., 13, 177 (1918). 



'Theory and Practice of Leather Chemistry,' ibid., 14, 93 (1919). 

 Wilson, J. A., and ICern, E. J. ' The Non-Tannin Enigma.' ' J. Am. Leather 



Chem. Assn.' 13, 429 (1918). 



COLLOID PROBLEMS IN BREAD-MAKING. 



By R. Whymper, Chief Chemist to Messrs. Peek, Frean c& Co., Ltd., 

 Biscuit Manufacturers, London, and late Assistant Inspector of Bakeries, 



B.E.F., France. 



There is no manufacturer less aware of the chemical problems 

 underlying his trade than the master baker. In spite of his ignorance, 

 however, he is one of the most efficient members of society, in that 

 he produces an excellent article with great regularity. This is, 

 perhaps, less a matter of wonder when it is reaUsed that the art of 

 bread- making of a high order can be traced through the Chinese to 

 about 2,000 years B.C., and is of course older than that, and that 

 even to this day the majority of people can make a very passable 

 loaf. 



Such scientific work as has been done, in or for the bakery, has 

 usually been undertaken for some specific material object, for advantage 

 to the large manufacturer (yields, moisture retainers, effect of machinery) 

 or for the protection of the consumer (sanitary conditions of manu- 

 facture, effect of alum, bleaching agents, &c.). There is comparatively 



