30 
IOWA ACADEMY OF SCIENCES. 
know that a layer of water equal in area to that of the 
disk has been torn apart by the counterpoise weights. 
Knowing the area of the disk and the number of grams to 
separate it we can calculate the number of dynes per 
centimeter to separate the molecules of water. 
Before giving the data and results of the experiment it 
may perhaps be well to state the precautions taken in the 
experiment. First, in order to insure that the water used 
was chemically pure, ordinary laboratory distilled water 
was redistilled in Jena glass vessels. All the ordinary 
tests failed to show traces of soluble salts in this water. 
Second, the disk was thoroughly cleansed by washing in a 
solution of potassium hydroxide; followed by washing in 
a solution of potassium dichromate and sulphuric acid; 
then in alcohol; then the disk was dried in a current of air 
and washed again in redistilled water. Third, a delicate 
laboratory scale with a rider weight was used in the ex- 
periment. 
Data: - Diameter of the disk. 
1 Measurement -106 62 m.m. 
2 Measurement — 106.98 m m. 
3 Measurv-^ment — 107. 27 m.m. 
4 Measurement — 106. 94 m.m. 
5 Measurement — 106.54 m.m. 
6 Measurement— 106. 74 m . m . 
7 Measurement — 107.20 m.m. 
Average 106.898 m.m. =10.6898 c.m. 
Test No. 1:— The number of grams to separate the disk 
from water at 4^,C. 
Trial 1:— 48.725. ' 
Trial 2:— 48.730. 
, . Trial 3:— 48.725. 
' Trial 4:— 48.733. 
. ■ : Average. .48.728. 
