IN EELATION TO CHEmCAL COMPOSITION. 
381 
valents of water ; but this would require confirmation. It is remarkable that hydrated 
liquid compounds appear in general to show only one decided transpiration maximum, 
as with the 1 -hydrate in sulphuric acid, the 2 -hydrate in acetic acid, the 3-hydrate in 
nitric acid, the 6 -hydrate in alcohol, and the 12 -hydrate in hydrochloric acid. 
A considerable number of experiments were made upon specimens of methylic alcohol 
prepared at ditferent times, with some discrepancy in the results. Although always 
derived from crystallized methylic oxalic ether, the liquid varied sensibly in transpira- 
bility. As the cause of this variation has not yet been ascertained, I shall confine my- 
self at present to one statement, namely, that a particular specimen of methylic alcohol 
gave 0‘63 as the transpiration-time of the anhydrous substance (water being 1 ), and 
1'8021 as the time of the 6 -hydrate, C 2 O 2 + 6 HO, and that for a considerable 
distance on either side of that point of hydration the transpiration was slightly less and 
nearly constant, as it is in \inic alcohol. It may be inferred, therefore, with some pro- 
bability, that alcohols have a maximum of retardation at the same stage of dilution. 
Three alcohols in a state of purity were transpired through the same capillary, with 
water for comparison, at 20°. The time of water was 297 seconds. 
Table IX. — Transpiration of Alcohols, at 20°. 
Transpiration-time. 
Specific gi-avity, 
at 15^ 
Boiling-point. 
In seconds. 
Water = 1. 
Methylic alcohol 
187-25 
0-630 
•7973 
66 C. 
Vinic alcoliol 
355’1 
1-195 
-7947 
78-5 
Amylic alcohol 
1084 
3-649 
'8204 
132 
It will be remarked that the transpiration-time of an alcohol increases with the elevation 
of its temperature of ebullition. A similar observation applies to the transpiration of ethers. 
Table X. — Transpiration of Ethers, at 20°, by Capillary C shortened. 
(Transpiration-time of water, 290 seconds.) 
Transpiration-time. 
Specific gravity, 
at 15°. 
Boiling-point. 
In seconds. 
Water =1. 
Formiate of ethyl 
148-2 
0-511 
•9174 
5.5-5 
Acetate of ethyl 
160-5 
0-553 
-8853 
74 
Butyrate of ethyl 
217-5 
0-750 
'8490 
114 
Valerianate of ethyl 
237-5 
0-827 
'8750 
133-5 
The transpiration-times of the homologous acids, previously observed, appear also to 
follow in progression. 
Transpiration of Acids, at 20°. 
Acid. Acid -|-2HO. 
Acetic acid 1-2801 2'740 
Butyric acid 1-565 3-279 
Valerianic acid 2-155 3-839 
3 G 2 
