Dee. 19281 WILKINSON ANU TYLER-"THE ABSORPTION 011' ACLDS BY WOOL-11" 3ti9

to intensify the differences by using basic dye- stuffs, e.g. Methylene Blue, which had a higher affinity for oxycellulose than for ordinary cellu- lose? The experiments of Mr. Pate1 showed that the affinity for Methylene Blue was decreased when the cotton was exposed to a high tem- perature.

The Lecturer said that the same resist effects were obtained with basic dyes as with direct dyes, thus showing that the effect was not pro- duced by what was ordinarily termed oxy- cellulose. This resistance to any class of colours could not be obtained unless during the singeing there was an excess of air present in the burning gas.

Mr. A. Herbert said the British Cotton In- dustry Research Association had shown that a t least two types of oxycellulose could be formed depending upon the concentration of hydrogen ions during the oxidation. By varying the p~ value of the system the nature of the oxy- cellulose formed varied in regard to its affinity for Methylene Blue.

Mr. F. Crompton said that in an attempt to re-dye a window blind, the portion which had been exposed to sunlight did not take the dye- stuff as well as that which had been on the roller. Was there any relation between such light exposure and heating?

The Lecturer thought it was quite possible. M i . J. It. Hannay said that there was no

general agreement as to what was meant by the term oxycellulose. Viscosity experiments were exceedingly interesting and enlightening in certain ways. But after all, the dyeing affinity of all fibres was associated with the hydroxyl groups. If the fibres were submitted to a very high temperature, was it not exceedingly prob- able that some of the hydroxyl groups would condense to form lactones, and that there would be a condition of fibre containing fewer hydroxyl groups '2 This might indicate the explanation of the type of result which the Lecturer had des- cribed.

The Lecturer said that raw linseed oil com- menced to dry more quickly on the tips of the singed fabric than it did on the tips of the un- singed fabric. It was very probable that the singeing did have Rome influence on the hydroxyl groups.

BRADFORD JUNIOR BRANCH A meeting was held on 1st November at the

Midland Hotel, Bradford, M i . C. 0. CLARK in the chair.

An address was given by Bernard Hickson, M.Sc., on "A Commercial Journey through Central and Eastern Europe." Mr. Hickson dealt with a recent journey on the Continent. He explained how necessary i t was to pay a personal visit to the countries in question if business was to result, it being practically im-

possible to introduce business by correspondence alone.

He dealt fully with the problems of labour and finance, and also spoke of the conditions of living in the various countries visited. After the address, an interesting discussion followed. The meeting was well attended, 22 members being present.

W. H. OXLEY Hon. Branch b'ecretmy

COMMUNICATIONS

The Absorption of Acids by Wool (Part 11-An Examination of the Experimental Data)

H. WILKINSON, A.I.C., and A. Ci. TYLER, M.Sc. (Drapers' Company Research

Xtudent )

In a. previous communication (Part 1, this Joour., 1928,44,241) we gave a summary of the work already published on this subject. The several investigators and theorists offer con- flicting opinions and different interpretations of their experimental evidence, A re-examination of the work in the light of more recent knowledge suggests that the differences are not necessarily as great as they a t first appear. Our main pur- pose in this communication is to submit such experimental data as we have obtained, and if possible discover where we are in agreement or disagreement with other workers.

Port and Lloydl0* draw attention to the difficulty in repeating any of their experiment>s so as to obtain concordant results. To standard- ise our conditions, preliminary tests were made to determine the influence of natural humidity upon the results. Samples of wool were dried (A) in the oven 1 hour a t 110" C., (B) in the oven 1 hour a t 95" C., (C) air dried a t room tempera- ture. They were then steeped in sulphuric acid solution overnight, and the acid retained by the wool determined. The following average figures were obtained-

o,!, Acitl Sarnple *(, Acid LJsecl J%ainecl

A ... ... 4 2.290 13 ... ... 3 2.292 c ... ... 3 2.401

This suggested that variations might be introduced by using pool in the air-dry con- dition, and this is supported by Wo~drnansey,~' who records variations in acid absorption by wools in different states of humidification. The difference between drying a t 95" C. and 110" C. was negligible, and the lower temperature was employed as less likely to cause changes in the wool, e.g. "browning." Steeping without a pre- liminary heating of the acid solution was tried, but it was evident from the small bubbles of air adhering to the wool a t the end of the operation that the wetting-out was incomplete. * For key to the numerical references 888 previous>mlJer, Part I

this Jwr . , 1938, 44,24B.