BETWEEN THE VISCOSITY OF LIQUIDS AND THEIH CHEMICAL NATURE. 691 
by means of the varying numbers obtained for n, these values can in general 
not be directly connected with the chemical nature of the substances, for such 
fortuitous variations in the value of n as those given by pentane and isopentane 
mask general relationships. 
It is also indicated that the general relation which connects the viscosities of all 
the foregoing liquids with the slope is 
so that knowing 77 ^ at the slope S^, it is possible to calculate its value at the new 
slope S 3 . 
The Alcohols .—As already stated, one formula of the type used by Slotte was not 
capable of representing with sufficient accuracy the observed values for the higher 
alcohols over the entire range between 0 ° and the boiling-point. It has already been 
stated, and it is evident from the table on p. 578, that even when several short range 
formulae are employed the values obtained for n are markedly in excess of the 
average value 1'76 obtained from the other substances. It is also evident from the 
different formulae obtained from the same alcohol that the value of n is not constant 
but falls as the temperature rises. This variation would probably take place in the 
case of any experimental curve if several formulae were deduced according to the 
method employed, inasmuch as a similar change is noticeable in the values of n as 
given by the formulae for water. 
This variation indicates that the magnitude of n is dependent ui^on the particular 
region of the curve to which the formula refers, and when it is remembered that for 
no two liquids is the portion of the curve compared between 0 ° and the boiling-point 
of the same extent, the variation lends further support to the idea that with such a 
method as that employed in deducing Slotte’s formula, little stress need be put upon 
such slight changes in the value of n as have been found for the majority of the liquids. 
The general mean of the 22 values obtained for n in all the formulse relating to 
the alcohols is 3'53, and this value differs so much from the mean value 1’76 obtained 
for the other liquids, that it is without doubt connected with the generic difference in the 
behaviour of the alcohols which is expressed in the peculiar shape of their viscosity 
curves. 
This large value for n, especially when it is borne in mind that for the alcohols h 
has also large values, also indicates that at a larger value of the slope their viscosity 
coefficients will not be related to those of the other liquids in the same way as at 
slope but will be relatively larger. 
From the unsatisfactory nature of the formula for the alcohols, it was not possible 
to estimate this difference by a general method. A new value of the slope was 
therefore chosen, and the corresponding values of 77 determined for the alcohols, and 
as many as possible of the other liquids. 
The value of the slope which appeared to be the most suitable was 'OgflQS, viz., that 
4 T 2 
