On the Elasticity of Spider Lines. 491 



minute in a normal solution of ester, and the correspond- 

 ing dissociation 0*12 X 10 -6 of a gramme-molecule per litre. 



Fig. 6. 



2- 



I - 



So H>0 tfo mo 2S~0 mi n.ute$ 



The great importance of this result is seen on comparison 

 with the following numbers. Shortly before. Ostwald found 

 in quite a different way that the electrolytic dissociation of 

 water lay between 0*74 X 10 -6 and 0*27 X 10~ 6 gram.-mol. 

 per litre ; whilst from Kohlrausch's conductivity determina- 

 tion he calculated that the maximum value did not exceed 

 0'6 xlO- 6 . Arrhenius obtained 0-11 xlO" 6 from Shields' 

 experiments, and Bredig estimated it at about 06xlO -6 

 gram.-mol. per litre. 



Is the theory of electrolytic dissociation hereby proved ? 

 By no means. In the domain of saponification it has never- 

 theless accomplished far more than could have been expected. 



XLVIII. Note on tlie Elasticity of Spider Lines. 

 By James H. Gray, 31. A. (Glas.), B.Sc. (Lond.)*. 



THESE tests were made last summer in the Physical 

 Laboratory of Glasgow University, in the course of some 

 work in which a very sensitive mirror- galvanometer was 

 required. 



When the mirror was suspended with a fine silk fibre, it 

 was found that, when deflected, it took an inconveniently 

 long time to return to zero. This defect, common to silk 

 and most metal suspensions, and which has been called 

 " creep," was, at the suggestion of Dr. J. T. Bottomley, 

 F.R.S., obviated by using a spider's thread for supporting 

 the mirror. 



* Communicated by the Author. 

 2 L2 



