"eR oh 
Fawr 
Pee. * 
Teas 
1910. ] with the State of Aggregation of Matter. 111 
Viscosities of Salt Solutions. 
The following measurements were made, as a direct comparison of the 
viscosities of the salts employed in the investigations was required under 
varying conditions of temperature, etc. The measurements were made at 
different temperatures also to determine whether any evidence as to the state 
of hydration of the salts in solution could be obtained. It was thought that 
the temperature coefficient would be large in the cases of heavily hydrated 
salts. The results indicate, however, that the state of hydration has 
probably only a minor influence on the viscosity. The low viscosity of sodium 
salicylate solution, compared with that of the benzoate, may possibly be due to 
the higher hydration of the latter (compare freezing-point determinations 
below). The results also indicate that sodium iodide and lithium chloride at 
lower temperatures may be more heavily hydrated than the other halides. 
The determinations were made by means of Scarpa’s apparatus,* in which, 
under a pressure somewhat higher than atmospheric, and indicated by means 
of a water manometer (in the results below, a plus pressure of 200 mm. of 
water was employed), a definite volume of liquid is made to pass both 
upwards and downwards through a capillary tube. In the results given 
below, the time required for passage in both directions is given. If attempts 
be made to transpose the numbers given below into absolute units by the 
equation 7» =x«t, where » = viscosity in absolute units, « = apparatus- 
constant, and ¢ = time of passage through capillary, it was found, using Thorpe 
and Rodger’s values for water at different temperatures, that « gradually 
became smaller with increasing temperature of the determination. This was 
due to the error arising from the formation of eddy currents, which were 
distinctly visible in the determinations made with liquids of low viscosity. 
As the error due to this factor is greater the lower the viscosity of the liquid, 
the differences between the determinations should be somewhat larger than 
those indicated in the table. The error does not detract, therefore, from the 
comparative value of the results. 
The most salient features of the following table are the high viscosities of 
the organic monobasic sodium salts as compared with the inorganic salts. 
Sodium formate occupies an intermediate position with a viscosity lower 
than the highest inorganic salt viscosity (sodium iodide, which only has such 
a relatively high viscosity at quite a low temperature) but lower than that 
of any of the other organic salts. The high viscosity of the benzoate 
compared with that of the salicylate is also to be noted. No other features 
of the table call for special comment. 
* ‘Archivio di Fisiologia,’ 1905, vol. 2, p. 246. 
