between the viscosity of liquids and their chemical nature. 625 
Homologues (continued). 
Difference. 
Methyl sulphide. 
335 
(6) 
Ethyl sulphide. 
346 
Dimethyl ketone. 
3.0 
(7) 
Diethyl ketone. 
343 
Methyl ethyl ketone. 
330 
14 
Methyl propyl ketone. 
344 
Formic acid. 
373 
- 3 
Acetic acid. 
370 
20 
Propionic acid. 
390 
- II 
Butyric acid. 
379 
Acetic anhydride. 
378 
( 1 ) 
Propionic anhydride. 
379 
Benzene . 
330 
24 
Toluene. 
354 
13 
Ethyl benzene. 
367 
At this condition of comparison the effect which an increment of CHg in chemical 
composition exerts on the magnitude of 17 varies within much narrower limits than 
when the boiling-point is used as the temperature of comparison. With the exception 
of the acids, which are still peculiar, and the dibromides, the effect in all cases is 
positive, and, in general, diminishes as the series is ascended. The large differences 
which exist at the boiling-point between the lowest members of series have now dis¬ 
appeared. 
The paraffins have no longer almost the same constants, but have values which 
vary regularly with the molecular weight. With the exception of propionic acid, the 
acids and anhydrides, which at the boiling-point had values which differed considerably 
from each other, have now practically the same viscosity coefficients. 
The alcohols, as already stated, cannot be compared at this particular value of tlie 
MDCCCXCIV.—A. 4 L 
