( 783 ) 



É ■r r , .(i+A 1 H*,« , )+M-« 1 



.4 (l + />> II , Cr II' ) A (Ij />'/< // i 



^ / /' r 'V ,./ / 



" " "•< 



+ -T-7; , .. „" -7 + 



=±H„ 



AAl+BMH) A (1 + />W/ ) A (H />/'//,) 



" -«O '11 ' 



(6) 



This formula holds also for (he carbonic acid thermometer up to 

 the number of decimals given by Chappuis. Id XV we shall further 

 discuss the deviation of the formula used by Chappuis. 



With a sufficient degree of approximation the formula for the 



determination of the temperature down to 0\001 with a hydrogen 



thermometer of 1100 m.M. zero point pressure and a «lead space 



11 

 — <^ 0.01 may be written in the simpler form: 



o 



F (l+V+£ s *') + & + «, 



H T 



+ ' , + 



A (l+Bi>]H ,_) 1 + 0.00366 t 



T 



it. 



+ , .'.„.„ + , >,'„. + 



//„ 



1 4- 0.00366 * a " 1 + 0.00366 < 3 ' 1+0.00366 / 4 



+ 



u 



A {\+Bf I[ o) 1 +0.00366X15 



(7) 



First an approximate value may be assumed for By. With the 

 approximate value of the temperature found i]i this way a better 



value of B'r may be determined, and the correction term for the 

 expansion of glass calculated. 



Thus we find At, from which the value of tt follows through 



A T - A Ta 

 0.0036618 



AT. Influence of thé deviation from the law of Boyle — Charles 

 on the temperature, measured with the scale of the gas thermo- 

 meter of constant volume according to the observations with 

 this apparatus. 



§ 1. When the formulae are drawn for the calculation of the 

 temperature on the scale of the gas thermometer of constant volume 

 the variation of pressure of the gas both in the thermometer-reservoir 



