THE 

 LONDON, EDINBURGH, and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



[FIFTH SERIES.] 



OCTOBER 1889. 



XXXII. Viscosity of Solutions. By R. F. D'Arcy, B.A., 

 formerly Scholar of Gonville and Caius College, Cambridge* . 



[Plate XI.] 



ri^HE following paper gives an account of experiments on 

 JL the determination of the viscosity of solutions, especially 

 as a means of investigating chemical changes going on in 

 them. 



The liquids experimented on were (1) solutions of sulphuric 

 and acetic acids of different concentrations at different tempe- 

 ratures, (2) solutions of chrome alum, (3) solutions of calcium 

 chloride in water, and ethyl and methyl alcohols. 



Experiments on Sidphuric-acid Solutions. 



In 1861 Graham communicated a paper to the Royal 

 Society (" On Liquid Transpiration in relation to Chemical 

 Composition/' Phil. Trans. 1861) containing the results of 

 experiments he had made, following up Poiseuille's observa- 

 tion that a solution of alcohol corresponding to C 2 H 6 . 3H 2 

 has maximum viscosity. One of the most striking observa- 

 tions recorded in this paper is that on adding water to sul- 

 phuric acid (which at 20° C. is about twenty-one times more 

 viscous than water) the viscosity increases, attaining a maxi- 

 mum when the water added is in the proportion of 18 to 98 

 of acid, that is to say, when the composition of the liquid is 



* Communicated by the Author. 

 Phil Mag. S. 5. Vol. 28. No. 173. Oct. 1889. S 



