DETERMINATION OF THE SPECIFIC HEAT OF WATER. 419 
TasLe I.—Comparison of Standard Clark Cell with C.T.C. Cell. 








1 | 2 8}. 4. 5 
Gen = {pais lar 
Observe 1 
Tere | eee berecune pete difference Calculated 
thermostat. standard. | pees LO difference. 
1891. e c 
Nov. 26 25:26 13:9 — 68 -- 67 
ye 25:2 127 — 78 —7 
Dec. 11 25:3 13:8 — 68 — 68 
eS) 25°4 11:9 — 81 — 82 
1892. 
Feb. 2 25-08 14-1 | — 63 — 65 
SoG | 25-4 12°6 — 76 — 76 
xy le 25-4 14:0 — 66 — 66 
| = 25°45 14-4 — 65 — 63 
March 1 | 25°7 13:2 — 73 — 72 
eS 25°52 11-4 =) | =186h | 
hy iD 25°65 11:2 — 8&7 — 87 
April 2 25°75 13:9 — 69 — 67 
ae Vo) 25:7 15-9 — i} — 52 
May 9 25°4 16:8 — 46 | — 45 
+ LO z 25°8 14-9 = 5S | — 59 
., 24 25°32 | 148 — 60 — 60 
Jane l 25°46 | 18:3 — 34 — 384 
Mean value. . oe 13:99 —663 | 



A small correction to the observed numbers is necessary, owing to the small varia- 
tions in temperature of the C.T.C. cell. The corrected values of 7 are given in the 
fourth column. As the C.1T.C. cell was not quite saturated with zinc sulphate when 
placed in the thermostat, the temperature coefficient 0004 was used to reduce its 
value to 25°. The corrections are so small that an accurate knowledge of that coef- 
ficient is not required. The mean temperature of the standard cell in all these 
experiments was 13°99, the mean value of 7 was 66°3. From these data we may 
calculate what the value of 7 should have been in each experiment, on the assumption 
that the temperature coefficient of the standard was -00081.* The values of 7, thus 
deduced, are given in the fifth column. With the exception of the experiment on 
May 20, the agreement is quite satisfactory ; and we are justified in concluding that 
the changes in the electromotive force of our standard cell may be correctly deduced 
* The temperature coefficient determined by Guazeproox and Skinner (‘ Phil. Trans.,’ vol. 183, 1892, A ) 
is ‘00076 between 0° and 15°—that is, for an average temperature of 7°°5. The temperature coefficient 
according to Kaute (‘ Zeitschrift fiir Instramentenkunde,’ August, 1893) is —:000814-—-000007 (t—15), 
giving an identical value for t=7°'5. 
3H 2 
