SECTIONAL TRANSACTIONS.— M, TEXTILES. 411 



species do differ in their response to soil conditions ; and manuring was obviously 

 a method of varying soil condition. There was, in fact, abundant evidence to disprove 

 Dr. Fisher's conclusion. 



The statement that the error in field experiments was ' almost wholly ' due to 

 differences in soil fertility was far too sweeping. They also had to deal with weeds 

 of all kinds, wireworm and numerous other insect pests, fungoid diseases of many 

 kinds, also with rabbits, birds and field-mice. The list of causes of error might, in 

 fact, be increased almost ad infinitum. As the diagram showed, some of these were 

 more or less systematically, but most of them quite erratically, distributed. 



In conclusion, the Lawes Agricultural Trust was to be congratulated on having 

 at last, after so many years, accepted the principle of the desirability of replicating 

 plots on different areas. 



SPECIAL SESSIONS FOR TEXTILE SUBJECTS. 



(For references to the publication elsewhere of communications entered in the 

 following list of transactions, see p. 435.) 



Thursday, September 1. 



Dr. S. G-. Barker. — Fading of Dyestuffs. 



Investigation of fading of dyestuffs shows that atmospheric influences and the 

 conditions under which the exposures are made have a considerable effect on the 

 amount of fading. Artificial light sources are compared with sunlight as regards 

 constitution and fading power. It is shown that the carbon arc is the best artificial 

 li<*ht for use as a fading agency. The influence of glass screens is discussed and 

 experimental results quoted to show the influence of shop window glass on fading, 

 &c. An outdoor fading cabinet and a new type of fading lamp giving controlled 

 conditions of humidity, temperature and illumination at the surface of the pattern 

 under test are described. The effect of tropical sunlight is compared with that of 

 sunlight in England. Methods of measurement of the amount of fading, &c, are 

 discussed. 



Dr. J. J. Hedges. — Moisture Relations of Colloidal Fibres. 



Textile fibres are Irygroscopic colloids, and their physical properties vary con- 

 siderably with the amount of absorbed water. In the case of wool fibre the whole 

 of the absorbed water is not removed by heating alone ; the last A per cent, of water 

 being held very tenaciously. 



During the absorption of moisture there is an evolution of heat, and for dry wool 

 the amount is quite considerable (24-1 calories per gram). The amount of heat 

 evolved by the textile fibres during absorption is given by a form of the Kirchoff 

 equation for the heat of dilution of a solution. 



Wool and its absorbed water behave like a two-phase system in which a little 

 water is absorbed by the colloidal particles while the bulk is held in a system of pores. 

 This hypothesis accounts for the lowering of vapour pressure of the water, the large 

 apparent compression of the latter, the peculiar rate of evaporation curves, the 

 change in length of a fibre under tension with change in moisture content, &c. The 

 heat of absorption can also be accounted for in such a system by surface energy 

 considerations. Under certain conditions, pores can be observed in textile fibres 

 under the microscope. 



The moisture content has a very definite effect on the electrical and thermal 

 conductivity. This has been investigated by a number of observers, and their results 

 are discussed in the paper. 



The amount of water held also affects the fastness to light of absorbed dyes. 

 With increasing moisture content, the dyes become more fugitive. 



Visit to Laboratories of the British Research Association for the 

 Woollen and Worsted Industries, Torridon. Papers : — 



Mr. A. T. King. — The Chemical Aspect of Wool Research. 



This paper gives in the first place a general indication of the wide scope of chemical 

 research in relation to wool and wool processes, and touches upon some of its more 



