544 Mr. A. Grilmour on the Resistance of 



Any of the electrons in any of the octets might act in this 

 way to fill the gaps in the layer of electrons round an atom. 

 Thus any octet might act like a nucleus from which chains 

 and side-chains of atoms ramified in every direction. As far 

 as geometrical considerations are concerned, there is nothing 

 to limit the number of certain kinds of atoms which could 

 be linked together in this way. It is probable that systems 

 built up in this way are too weak to have any but the most 

 transient existence ; but the possibility of their formation to a 

 limited extent in certain cases ought not to be lost sight of. 



XL VI. On the Resistance of Solutions of Copper Sulphate 

 in Glycerine. By A. Gilmour, M.Sc, 1851 Exhibition 

 Scholar, Queen s University, Belfast *. 



IN many laboratories a high resistance of very small induc- 

 tance and capacity is becoming very desirable. In the 

 physical laboratory of Queen's University, Belfast, a mixture 

 of glycerine and copper sulphate has been used for some 

 years for high-resistance potentiometer and other high- 

 resistance work. During the past year variable resistances 

 of very large value and negligible inductance and capacity 

 were required in connexion with some work undertaken on 

 valves f, and, on investigation, glycerine-copper sulphate 

 solution proved very suitable. 



Though glycerine has been known for a long time as a 

 solvent of very wide range — at least as extensive as that of 

 water — very little work has been done on the resistance of 

 glycerine solutions prior to that of Jones and his colla- 

 borators J. They investigated the molecular conductivity of 

 a large number of salts dissolved in glycerine and in mixtures 

 of glycerine and water, but make no mention of glycerine- 

 copper sulphate mixtures. In this paper the specific re- 

 sistances of various mixtures of these substances are dealt 

 with for convenience in laboratory work. 



Method of Measurement. 



The cell used to measure the resistance was an inverted 

 U-tube a (fig. 1) into the horizontal part of which a glass 

 tube with a bulb b was sealed ; the latter acted as a reservoir 

 for any extra solution drawn up by the rubber bulb c, by 

 compressing and releasing which the U-tube was filled- 

 The ends of the U-tube were encased by spirals of copper 

 wire e e, which acted as electrodes and dipped well under 



* Communicated by the Author. 



+ Beatty and Gilmour, Phil. Mag. Sept. 1920. 



£ Jones and collaborators, Carnegie Inst, of Washington, No. 180, 1913. 



