100 
DH. T. E. THOllPE AND MR. J. W. RODGER ON THE RELATIONS 
Ethers. 
i 
tjd- (Obs.). 
(Calc.). 
0<. 
Diethyl. 
4.59 
408 
51 
j\lethy] propyl. 
471 
409 
63 
Ethyl propyl. 
534 
470 
61 
Dipropyl . 
601 
532 
69 
IMethyl isobutyl. 
534 
485 
49 
Ethyl isobutyl. 
593 
.547 
46 ' 
As regards both molecular viscosity and molecular viscosity work, tlie formates— 
as was to be expected from what has been already stated—give values which are 
much larger than tliose of other compounds. Of the remaining liquids the general 
mean of the values of ethers and esters as regards molecular viscosity is 62 8. 
The variations of the individual values are no doubt large, arising mainly from the 
fact that in the case of normal isomers the same calculated value is deducted from 
the observed numbers, no regard being paid to the effect of symmetry of the 
molecule, etc., on the viscosity. A quantitative measure of these effects will only 
be possible after a much larger number of compounds has been investigated. There 
can, however, be no question of the large differences which exist between the atomic 
constants of hydroxyl oxygen, carbonyl oxygen, and ether oxygen. 
Taking the value found above, we may now write as the probable values of oxygen 
in the three different conditions— 
Molecular 
Molecular 
Viscosity. 
Viscosity Work. 
Hydroxyl oxygen .... 
196 
102 
Carbonyl oxygen .... 
248 
41 
Ether oxygen. 
62 
37 
These numbers, of course, can only be regarded as provisional; they are mainl}’ put 
forward as confirming the conclusion already indicated in our previous paper, that 
the constitution of oxy-compounds largely affects their viscosity. 
