ME. T. (IE ATT AM ON LIQUID DIFFUSION APPLIED TO ANALYSIS. 
197 
Table X. — Diffusion of a mixture of 4-01 per cent, of Chloride of Sodium and 5 ’99 per 
cent, of Sulphate of Potash (equivalent proportions), for seven days, at 14°. 
Number of 
stratum. 
Potassium, 
in grammes. 
Sulphuric acid, 
in. grammes. 
Total diffusate, 
in grammes. 
1 
•028 
•002 
•023 
0 
•034 
•002 
•030 
3 
•049 
•004 
•044 
4 
•064 
•009 
•065 
5 
•092 
•015 
•096 
6 
•128 
•031 
•149 
7 
•172 
•059 
•219 
8 
.042 
•104 
•315 
9 
•435 
]0 
•600 
11 
•797 
12 
1*025 
13 
1*261 
14 
1*480 
15 and 16 
3-467 
10-016 
The weight of the mixed salt Avas always 10 grammes. The diffusions exhibited in 
the tAvo Tables are strikingly similar, and indeed may be considered as identical. It 
thus appears that the diffusion of the metals is not affected by the acid Avith Avhich they 
are in combination. The result is quite in harmony with Beethollet’s view, that the 
acids and bases are indifferently combined, or that a mixture of chloride of potassium 
and sulphate of soda is the same thing as a mixture of sulphate of potash and chloride 
of sodium, when the mixtures are in a state of solution. With tAVo acids very unequal 
in their affinity for bases, the result possibly might be very different. 
2 . Effect of Temperature on Diffusion. 
Diffusion is promoted by heat, and separations may accordingly be effected in a shorter 
time at high than at low temperatures. In a series of obseiwations made upon hydro- 
chloric acid, the diffusion of that substance Avas carefully determined at 15°-5 (60° F.), 
and at three higher points, advancing by Il°-ll (20° F.). The ratios of the diffusions 
observed Avere as folloAvs : — 
Diffusion of hydrochloric acid at 15°’55 ( 60° F.), I 
„ „ at 26°-66 ( 80° F.), 1-3545 
„ „ at 37°-77 (100° F.), 1-7732 
„ „ at 48°-88 (120° F.), 2-1812. 
The increments of diffusibility, 0-3545, 0-4187, and 0-408 for equal increments of 
temperature, are probably affected by small errors of observation, but they appear to 
indicate that the diffusion increases at a higher, although not greatly higher, rate than 
tlie temperature. The aAm-age increase of diffusibility for the Avhole range of tempera- 
ture observed is 0-03543, or for each degree (0-01969, or 3 ^ nearly for 1°F.). 
