[cARR] AN EXTENSION OF PASCHEN’S LAW 179 
And at the minimum discharge potentials which are again con- 
stant, 420 volts, the readings given are:— 




Distance between electrodes Discharge pressures in 
in mm. mm. of mercury, 
1 5°02 
2 2°52 
3 1°63 
5 1°07 
10 510 

Special attention is directed to these latter results, inasmuch as 
the exactness of the ratio indicated by the pressures is very remarkable 
The ratios of the pressures are practically 10: 5: 3-1: 2: 1, the nearest 
approximation to the numbers demanded by Paschen’s law which has 
been shown by any of the comparisons, and this result is all the more 
convincing in that these figures were obtained at the critical points 
where in the other two gases the results obtained indicated the law 
in a somewhat less marked degree. 
Fig. Vi Carbon DIOx/de 
+ |d= |/m 
x fat 2m 
/0 M, 
6 4 
Beewer Ox De ana Dies ce pes Zec/Foaes 
Though it would appear that further evidence was unnecessary, 
the table of products was again calculated and is given in Table VI. 
Also the corresponding curve is shown in Fig. VII. 
. Once more the regularity of the curve shows that as in air and 
hydrogen so in carbon dioxide Paschen’s law is rigidly applicable to 
all spark potentials both above and below the critical pressure. 



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