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MESSRS. T. E. THORPE AND J. W. RODGER ON THE RELATIONS 
certain conditions of measurement, successive observations on the same liquid vary 
by as much as 12 jDer cent. 
The comparisons of the specific viscosities were given at temperatures differing by 
a 5° interval between the maximum limits of 10 ° and 60°. The main conclusions 
which may be deduced from their work, which of course refers to specific viscosities 
measured at one and the same temperature, are stated by them as follows :— 
1 . The substitution in a molecule of Cl, Br, I, and NO 3 for H, in all cases increases 
the specific viscosity of the substance. This increase is smallest on the introduction 
of Cl, and increases on the introduction of Br, I, and NO 2 , and in the order given. 
The absolute amount of the increase depends not only upon the nature of the 
substituting radicle but also upon its position in the molecule. 
2 . Isomeric esters have nearly the same specific viscosity. Of two isomeric esters 
that possesses the greater specific viscosity which contains the higher alcohol radicle. 
3. The ester containing the normal radicle has always a greater specific viscosity 
than the isomeride containing the iso-radicle, and this obtains no matter whether the 
isomerism is in the alcohol or the acid radicle. 
4. The normal aldehydes have invariably a greater specific viscosity than the 
iso-compounds. In the case of the alcohols the results are conflicting, although as a 
rule the normal compounds have a greater specific viscosity than tbe iso-alcohols. 
5. The alcohols have a greater specific viscosity than the corresponding aldehydes 
and ketones. 
6 . In homologous series, in general, the increase in specific viscosity is proportional 
to the increase in molecular weight ; the actual amount of increase is, however, 
dependent u])on the constitution of the molecule, and only becomes constant when 
the members of the homologous series, considered as binary compounds, contain one 
constant and one variable member. 
Pribram and Handl’s work undoubtedly constitutes a great advance upon that 
of their predecessors. But whilst it establishes the broad fact of a connection 
between the viscosity of a liquid and the chemical nature of its molecules, it cannot 
be said that the numerical results afford us any accurate means of determining the 
quantitative character of this connection. This is probably due partly to the 
imperfection of their observational methods and to their mode of treating their 
results, and partly also to the uncertainty of the basis of comparison ; possibly, also 
the nature of the liquids themselves may have occasioned, to some extent, the 
equivocal character of the results, for it is impossible to gather from such data as are 
given that the liquids approached the standard of purity which is desirable in an 
investigation of this kind. 
B. Gartenmeister (‘ Zeits. fiir physik. Chemie,’ vol. 6 , p. 524, 1890) has also 
determined the viscosity of a large number of organic substances and has expressed 
his results in absolute measure. His method consisted in allowing the liquid to flow 
from bulb-shaped pipettes through capillary tubes in the manner already adopted by 
