Measure of Resistance to Galvanic Currents. 29 
be screwed up against the mouth of the tube. The receiver was 
then properly secured and filled with clean mercury, which was 
suffered to run down the slightly inclined tube into a vessel 
placed below. When all the air-bubbles, which at first appeared 
adhering to the sides of the tube, seemed to be carried away by 
the descending stream of mercury, the lower orifice of the tube 
was tightly closed by means of the screw and plate; the tube 
was placed im a vertical position, and its upper end withdrawn 
from the caoutchouc covering. When this was done with care, 
the vertical tube was found entirely filled with a column of 
mercury which terminated in a projecting hemisphere of the 
metal. The upper orifice was next closed by pressing against it 
a glass plate ground flat, the superfluous metal being thus 
removed. The tube being then freed, by means of a brush, from 
any globules of mercury that might have adhered to its surface, 
was emptied into a glass vessel, and its contents weighed on an 
accurate chemical balance. When the precaution was taken of 
Jetting the mercury flow slowly from the tube by inclining it 
very slightly, and suffermg the air to enter gradually at the 
upper orifice, 1t was found that no globules were left behind in 
the tube, as is generally the case under other circumstances. 
Warming the tube when full by contact with the naked hands 
was of course avoided. The temperature at the time the tube 
was filled was observed, and the weight of the contents corrected 
for the difference of this above 0° C. Of the following Tables, 
Table I. gives the lengths of the threads of mercury observed in 
gauging the capacity of the tubes employed, and the ratio a of 
the greatest and least section thence determined. Table II. the 
weight of the mercury at the actual temperature, and the same 
as corrected for 0° C. 
Table I. 
1, a 3. 4 5. 6. 
125-0 | 101-2 48-2 143-0 115 111 
116-4 98-4 47-5 145-0 116 109 
115-3 96:9 450 146-0 119 107 
114-0 04:5 45-0 145 0 121 105 
112-0 94-0 44-8 143-5 121 105 
110-2 93°38 44-2 1425 122 103 
108-2 94:5 43-9 142°5 121 101 
107-0 95:7 43°7 140-0 | 120 100 
107-0 97-5 42-5 139-0 119 Lois | 
106-0 99-4 ANEOD PG 3.0536 ace ts 102 
101-1 AO cloarctin pela h a 100 
=e ie 125 | 101-2 48-2 | 146 122 | lil 
106; 933 | 401 | 139 | WS | Too 
