Corrections of the Nitrogen Scale. 
535 
The corrections at higher temperatures, where the 
hydrogen thermometer cannot be used, are of more interest. 
A comparison of these values is given in Table V., Oallendar's 
values having been reduced to 7r=1000 mm. as before. The 
relation of the several sets of corrections may be seen from 
the curves in Plate XYIT. Curve A represents Berthelot's 
values. Curve B x represents the values computed by equation 
(14) with Holborn and Austin's values of C p . Curve B 2 
represents the results obtained by means of equation (11). 
Curve C represents Callendar s results. The greatest dis- 
crepancy at 1000° is less than o, 4, an amount which is 
negligible in the present state of gas-thermometry. 
Table V. 
Constant-Pressure corrections for Nitrogen at high 
temperatures. 7r=1000 mm. 
(The corrections are to be added to the constant-pressure readings.) 
■■ 
2, 
3. 
4. 
5. 
6. 
.... 
t°C. 
Callendar. 
Bertbelot. 
Buckingham 
(equ.ll). 
Buckingham 
(equ. 14). 
Buckingham 
(equ. 15). 
200 ... 
0-135 
0113 
0128 
0-105 
400 ... 
0-457 
0-523 
433 
0-456 
450 ... 
0-660 
600 ... 
0844 
0-992 
0827 
800 ... 
1-248 
1-492 
1-262 
1000 ... 
2-047 
1-654 
2-007 
1-706 
1-721 
1200 ... 
2532 
2157 
2-170 
1600 ... 
3-596 
2000 ... 
... 
4-072 
The agreement of Bj with A and of B 2 with C is so close 
as to suggest premeditation. In reality equation (14) was 
developed and the values represented by curve Bj computed 
before the writer had succeeded in obtaining a copy of 
M. Berthelot's paper. That paper then suggested further 
work which resulted in the development of equation (11) 
from which were computed the values represented by curve B 2 . 
Equations (14) and (15) w r ere deduced on the assumptions 
that the critical pressure of hydrogen was 19'4 atmospheres 
and 13 atmospheres, respectively. It is evident therefore, 
upon comparing columns 5 and 6 of Table Y.. that small 
errors in the critical constants, while they have some influence 
on the reduced equation for //, or /jlG p , are almost entirely 
eliminated in the process of finding the coefficients of the 
corresponding unreduced equation. 
