BETWEEN” THE VISCOSITY OF LIQUIDS AND THEIR CHEMICAL NATURE. 695 
above conditions, the results will be general, and related to the chemical nature of 
the substance. 
By trial we have found that if slopes be chosen which satisfy the relationship 
or. 
(Sa. . ^A . 
(Sa,. C 
+ 1) 
^i/(«A + i)Wa/Oa + n - 
= (Sb, . Wb ■ = &C., 
= (Sb, . %. ^ = &c., 
the condition for generality is fulfilled, the slopes obtained are almost the same, and 
they are chosen according to a system, as the constants employed are c and n, which 
occur in the formulae of the particular liquids. 
The same conditions are also satisfied if instead of either (n + 1) + U Qp 
be substituted in the above equations. 
At all these conditions of comparisons, however, the stoichiometric relationships 
are no more definite than at temperatures of equal slope. We do not propose, 
therefore, in the present state of the question, to give details of the results obtained. 
The above discussion, however, may serve to show how it is possible by means of 
slope comparisons, and with a simple formula like that of Slotte’s, to insure that 
the results obtained shall be general, even when n varies. 
The fact that the above somewhat complex methods lead to no better physico¬ 
chemical relations than the simple method of equal slopes, may also be taken as a 
further indication that, at least for liquids in which the molecular complexity does 
not change with the temperature, in a formula of the type employed, if it could 
be made to agree more closely with actual observations, the constant n would 
be the same. This again indicates that at temperatures of equal slope the results 
may be taken to be general as well as comparable. 
Conclusions relating to the Generality of the Results Obtained at the Temperatures of 
Equal Sloq)e, and to the Comq)arisons in which a Different Sloq)e is Employed 
for each Liquid. 
1. From the preceding discussion it is evident that over such temperature-ranges 
as our observations extend the results obtained at a particular value of the slope 
maj^ be regarded as general for all liquids, with the exception of the alcohols 
where the relationships vary slightly as the slope alters. 
2. It is further indicated that in the present state of the question equal slope is 
the most suitable condition at which to compare the viscosities of different liquids. 
Comparisons of the Magnitudes of the Temperatures of Equal Slope. 
In the preceding comparisons we have been concerned with the values of the 
various viscosity magnitudes corresponding with points on the viscosity curves 
