Temperature on the Specific Heat oj Aniline. 69 



I have shown (p. 65) that the error introduced by this 

 uncertainty is in any case small, more especially so as the 

 results are deduced from differences in the ordinates. The 

 most probable position appears to me to be about midway 

 between the points of intersection of the 2-cell line with the 

 other lines ; but as it is improbable that the position of the 

 point would vary capriciously as the temperature rose. I have 

 selected points on the smoothed curve (called the " null-point 

 curve ") which passes most nearly through the various inter- 

 sections. 



It will be noticed that the null-point curve approaches more 

 nearly to the outside temperature as the value of 1 increases *. 

 This indicates either (1) that the work done by the stirrer 

 had diminished (this would probably be due to diminished 

 viscosity or surface friction) ; or (2) that the loss by con- 

 vection, &c, had increased. The former is I think the more 

 probable explanation. 



When the depth of the liquid is increased, the stirrer has more 

 work to do and the supply of heat is greater while the loss 

 remains unchanged. The null point therefore is at a higher 

 elevation when the mass is greater, and PI. I. shows that 

 $isr — #o is nearly proportional to the depth, i. e. to the mass, of 

 the contained liquid. 



In order to illustrate the method of applying the various 

 corrections, and also to indicate their comparative magnitude, 

 1 give in full (Table ITL) the working out of experiment 26, 

 of which the details were given in Table II. The numbers in 

 Roman numerals indicate the sections on the preceding pages, 

 in which the particulars of the correction are given. The 

 greatest correction is that given by the calibration of the 

 bridge-wire, and this can be applied with great certainty. 



I do not consider it necessary to crowd this paper with 

 similar details regarding the remaining experiments. Table 

 IV. (pp. 71, 72) is a summary in which I have given the 

 numbers necessary for the remaining calculations. 



* This curvature is more marked than would at first sight appear from 

 an inspection of Plate I. Owing to the difference in the temperature 

 coefficient of the two differential thermometers, the true bridge null point is 

 given by the expression 59 -84 + "0003 X , where 1 is the temperature of 

 the thermometers. The position of the bridge null point is shown by 

 the vertical lines on the left. 



