170 



J. G. STEPHENS. 



measurements may be conducted need not be emphasised. 

 After the work which forms the subject of this paper had 

 been completed, my attention was drawn by Mr. J. W. 

 Hogarth of the University, to papers by Blackman and 

 Barger, 1 in which a somewhat similar method is described. 

 As the principle of Blackman's method is slightly different, 

 however, the present description may not be entirely with- 

 out value. 



In conclusion I wish to express my thanks to Professor 

 O. E. Fawsitt, for much advice and encouragement in the 

 course of the present investigation. 



Chemical Laboratory ', University of Sydney, 



Trans. Chem. Soc, 1905, 87, 1474, 



