between the viscosity of liquids and their chemical nature. 595 
Normal Propyl and Allyl Compounds. 
Normal propyl. 
Difference. 
Allyl. 
'/• 
'/• 
Hydrocarbons. 
201 
(6) 
192 
Iodides . 
353 
9 
344 
Bromides. 
325 
10 
315 
Chlorides. 
274 
12 
262 
Alcohols. 
463 
90 
373 
Ethylene and Acetylene Bromides. 
Ethylene. 
Acetylene. 
Bromides. 
514 
72 
442 
With the exception of the alcohols, a normal propyl compound has invariably a 
slightly larger coefficient than the corresponding allyl compound, the average 
difference being some 9 units. It is noteworthy that diallyl and normal hexane are 
related in the same way as the halogen derivatives. In the case of the alcohols, the 
difference is still in the same sense but has reached the value of 90 units, or 10 times 
its magnitude in the preceding comparisons, a result no doubt due to molecular 
complexity. 
Ethylene and acetylene bromides may be compared here, as they differ in consti¬ 
tution in the same way as normal propyl and ally] compounds. The saturated 
compound has a coefficient wBich is the larger by some 72 units, a value comparable 
with that given by the alcohols. 
Isologous Hydrocarbons. 
n. 
(Normal) 
Difference. 
C«H.„. 
Difference. 
C„Ho«_o. 
Difference. 
C.H,._6. 
>h 
'/• 
'/• 
V- 
0 
200 
15 
185 
12 
188 
6 
204 
12 
192 
-112 
316 
7 
199 
- 49 
248 
8 
198 
• • 
• • 
- 35 
233 
4 G 2 
