1902-3.] Freezing-Point Depression in Electrolytic Solutions. 369 
As a check on the readings, a thermometric reading was made 
after the filtration had been completed. Notwithstanding the 
changed conditions owing to the filtration, this reading did not 
differ from the equilibrium reading when the vessel was fully 
charged by 0‘0005°. The apparatus was now removed from the 
ice bath, thoroughly cleaned, and used for a second precisely 
similar experiment, hydrochloric acid or some similar substance 
being used instead of acetic acid. 
The following numbers will serve as an example of our experi- 
mental data: — 
I. — Barometer 762*7 mm. Boom temperature 15 *7°. 
80 c.c. water and 45 grams wet ice. 
Time, 
h. m. 
Thermometer. 
Micrometer. 
11.0 
5-06° 
8*0 
11.15 
9-0 
11.35 
8*9 
Added 11 ’5 c.c. normal acetic 
acid. 
11.45 
5-24° 
25-0 
11.55 
22*0 
12.0 
22-0 
12.5 
22-0 
12.19 
22*0 
Filtered off two portions. 
II.— 
■Barometer 763'0 
mm. Room temperature 15 '3°. 
80 c.c. water and 45 grams wet ice. 
Time. 
Thermometer. 
Micrometer. 
12.58 
5-06° 
8-0 
1.2 
8-7 
1.47 
8-9 
Added 57 c.c. normal hydro- 
chloric acid. 
1.55 
5*25° 
2*0 
1.59 
2-0 
2.31 
2*0 
Filtered off two portions. 
The readings on the thermometer aie the divisions on its scale 
to which the zero of the micrometer scale was adjusted, so as to 
measure back to the meniscus. Since the two scales read in 
opposite directions, the freezing-point depression may be obtained 
by adding each thermometric reading to its appropriate micro- 
meter reading, and then subtracting the one temperature from 
the other. Thus in the first example, the lowering of the freezing 
point is (5‘24° - S’OG 0 ) + (22*0 — 8’9) divisions. From the cali- 
bration table it is then found that this corresponds to a depression 
in terms of the thermometer scale of 0T844°. Each division on 
