ON COLLOID CHEMISTRY AND ITS INDUSTRIAL APPLICATIONS. 305 
Colloid Chemistry and its General and _ Industrial 
Applications.— Summary Report of the Committee (Professor 
F. G. Donnan, Chairman; Dr. W. Crayron, Secretary; Dr. E. 
Arprry, Dr. E. F. Armsrrone, Sir W. M. Bayriss, Professor 
CG. H. Descu, Dr. A. E. Dunstan, Mr. H. W. Greenwoop, Mr. 
W. Harrrson, Mr. BE. Hatscnex, Mr. G. Kina, Professors W. C. 
McG. Lewis and J. W. McBary, Dr. R. S. Moretu, Professors 
H. R. Procrer and W. Ramspen, Sir E. J. Russevn, Mr. A. B. 
SmARLE, Dr. S. A. SHorrER, Dr. R. E. Suave, Mr. F. SPROXTON, 
Dr. H. P. Stevens, Mr. H. B. Stocks, Mr. R. WHymper). 
Tux Fifth Report was published by the Department of Scientific and Industrial 
Research, and contains an index to the five reports now issued. Six papers 
have been contributed, of which the following are brief abstracts :— 
(I.) The Measurement of Surface Tension. By Allan Ferguson, M.A., D.Sc. 
(East London College). 
‘This report deals with recent advances in the methods and technique used 
in the determination of surface tensions. It advisedly concerns itself with 
methods rather than results, for it is now clearly recognised that an accurate 
knowledge of the tension in surfaces separating a liquid from a vapour phase, 
and, more especially, of the tension in a liquid-liquid or a liquid-solid interface, 
is a first condition for the quantitative discussion of many of the problems of 
colloid chemistry and physics.’ 
The very important subject of the measurement of contact-angles is first 
dealt with, and then the various methods for determining the surface tension 
at a liquid-gas interface, special attention being paid to the capillary-rise method. 
The methods used in determining interfacial tensions are discussed, the 
modern work of Harkins and his collaborators receiving detailed treatment. 
The great defects in the drop-number method are clearly pointed out, and atten- 
tion is directed to a promising new method of determining interfacial tensions 
now being investigated by the author. 
(II.) Report on Collagen and (relatin. By Professor H. R. Procter, D.S8c., 
F.R.S. (University of Leeds), and J. A. Wilson, D.Se. (Chief Chemist, 
Messrs. A. F. Gallun & Sons Co., Milwaukee, U.S.A.). 
The authors present separate accounts of the work done in Europe and 
America, the latter being dealt with first. 
The comprehensive work of Loeb on gelatin is well summarised, his experi- 
ments seeming to indicate that proteins combine only with cations on the alkaline 
side of the iso-electric point, and only with anions on the acid side. According 
to the Procter-Wilson theory, the combination of protein and hydrogen ion is 
governed by the law of mass action, and Loeb’s experiments are in keeping with 
the theory. The work of Loeb and of Procter and Wilson on the Donnan mem- 
brane equilibria is briefly dealt ‘with. 
In connection with the European work, discussion is made of the researches 
of Miss D. L. Lloyd on the swelling of gelatin in relation to the p, of the 
medium, and of Atkins’ papers on the same subject. 
_ The elucidation of the ultimate structure of jellies, and especially of gelatin 
jelly, occupies considerable space, dealing with the work of Hatschek, Procter 
and Wilson, McBain, von Gaza, Bradford, Barratt, and others ; incidentally, the 
Liesegang phenomenon is dealt with. Kubelka’s important work on collagen 
concludes the paper. 
(III.) Colloid Phenomena in Bacteriology. By Eric K. Rideal, M.A., D.Sc. 
(University of Cambridge). 
The subject is treated under the headings: Bacteria as colloidal systems ; 
bacterial growth; surface adsorption; chemical constitution and adsorption: 
selective action ; conclusions. 
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