ME. T. GBAHAM ON LIQUID DIUFUSION APPLIED TO ANALYSIS. 
191 
chloride of sodium appears to be pretty nearly three times greater (or more rapid) than 
that of sugar. 
The following experiments were made upon hydrochloric acid and chloride of sodium 
at a somewhat lower temperature and for times which are different, but which give a 
nearly equal difiusion for each substance. 
Table IV. his . — 10 per cent, solutions. 
Number of stratum. 
Hydrochloric acid, 
in grammes. 
Three days at 5°. 
Chloride of sodium, 
in grammes. 
Seven days at 5°. 
1 
•003 
•003 
2 
•006 
•009 
3 
•012 
•010 
4 
•022 
•026 
5 
•043 
•055 
6 
•086 
•082 
7 
•162 
•165 
8 
•308 
•270 
9 
•406 
•403 
10 
•595 
•595 
11 
•837 
•823 
12 
1-080 
1-085 
13 
1-163 
1-270 
14 
1-578 
1-615 
15 and 16 
3-699 
3-589 
10-000 
10-000 
The diffusion of hydrochloric acid in three days corresponds closely with the diffusion 
of chloride of sodium in seven days. The times of equal diffusion for these two sub- 
stances, at the temperature of the experiment, appear accordingly to be 1 (hydrochloric 
acid) and 2'33 (chloride of sodium). Hydrochloric acid and the allied hydracids, with 
other monobasic acids, are the most diffusive substances known. The general results of 
several series of experiments may be expressed approximately by the following num- 
bers : — 
Ap-proximate times of equal diffusion. 
Hydrochloric acid 1 
Chloride of sodium 2 ’33 
Sugar 7 
Sulphate of magnesia 7 
Albumen 49 
Caramel 98 
It is curious to observe the effect of changing the liquid atmosphere in which diffusion 
takes place, which is water in all these experiments, and replacing it by another fluid, 
namely alcohol. Two substances were difliised in the usual manner, but with this differ- 
ence, that the substances were dissolved in alcohol, and the solutions placed under a 
column of the same liquid in the jar. The alcohol was of sp. gr. 0*822 (90 per cent.). 
