DETERMINATION OF THE SPECIFIC HEAT OF WATER. 439 
corrections under the condition of our experiments have to be diminished by 0°00046 ; 
hence, if ¢ is any interval of temperature on the standard thermometer, and ¢, that on 
the Baudin thermometer, we find finally 
t = ty (1 — ‘00135). 
We have made a few observations which check the correction (:00046) we have 
made to eliminate the error due to the fact that, in the actual equivalent experiment, 
the zero of our Baudin had not reached its final state. The Baudin was placed in 
water at a temperature 10° above that at which it had previously been kept, and was 
compared after the lapse of about ten minutes with the standard. The latter instru- 
ment had been immersed in the warm water for several hours, and its zero was 
determined at the conclusion of the comparison. The corrections thus found on three 
different days for the Baudin were — 0°:0059, — 0°:0069, — 0°:0053, or — 0°-0060 
in the average, at a mean temperature of 22°°6. ‘Taking the correction at 12° to be 
that found above, viz., 0°°0082, we should get an interval correction of — 0°-60142, 
holding for the conditions of the experiment closely resembling those of the equivalent 
experiments. The difference between this number and the one adopted (—0:00135) 
is less than one part in a thousand. 
The Calorimeter and Water-equvalents. 
The calorimeter consisted of a copper vessel, heavily gilt outside and inside, the 
weight of gold deposited being about 1°6 grms. The copper vessel was of the usual 
cylindrical form, and had the following dimensions :—- 
ileteht? = Tavlos: eas es Pall7-9¥centims: 
Diameter owsection: ss eee) L10 4. 
itincknesstomwallsW (ies are. 0°0295 centim. 
Total weight of calorimeter . 161°3 orms. 
The following data will show the agreement between different determinations of 
the specific heat of copper :— 



TaBLE VI. 
Range of tempera- Mean | ipa Wepa ae 
Observer. Specific heat. | ture through which | temperature of Be im eS 
copper was cooled. | of copper. | ok 
fo} (e) ° fe) Ap 
Reenautt (Naccari)* 0933 100-17 59 17 
| ToMLINSON . . . . 0938 100 — 20 60 20 
POGSt aa, Cee te ae meee 0933 100-15 58 | 20 
JOULES irae et 0921 40- 8 24. 7 
| TOMMINSON 9 > ' 2-2 0926 60 — 20 40 20 





* REGNAULT gives a higher value, based apparently on a wrongly-assumed value of the specific heat 
of lead. The above value is that which Naccari has recalculated from RErGNAULT’s observations, 
correcting for the error. 
