260 Dr. C. R. A. Wright on the Determination of 



perature of 19°*7 ? produced (on an average of four accordant 

 experiments) enough heat to raise 3036 grammes of water 1°, 

 the water being at an average temperature of 20°* 7, and the 

 calculation not including the heat required to raise the water 

 produced from the average initial temperature of 19° # 7 to the 

 average final temperature 21°'8. Since a litre of hydrogen at 

 0° and 760 millims. weighs 0*089578 gramme (Regnault), 

 the corrected heat-evolution per gramme of hydrogen burnt 

 (i. e. per 8*98 grammes of water produced) would suffice to 



heat +19 = 33,911 grammes of water 1°, the water 



being at 20 o, 7. According to Regnault's formula the specific 

 heat of water at 20 0, 7 is 1*00122 ; according to Bosscha's 

 formula, 1*00455. Hence the heat-evolution is 33911 x 1*00122 

 = 33952 (Regnault's formula), or 33911 x 1*00455 = 34065^ 

 (Bosscha's formula). To this must be added a quantity e—f 

 to reduce the value to that which would have been produced 

 had the gases and water formed been all at 0°, e being the 

 heat given out by 8*98 grammes of water in cooling from 

 19°*7 to 0°, and /that required to heat up the constituent 

 hydrogen and oxygen from 0° to 19°*7 ; so that e—f is sen- 

 sibly 76 gramme-degrees ; whence finally the heat-evolution 

 becomes 34,028 by Regnault's formula, and 34,141 by 

 Bosscha's formula. 



30. These reduced values may therefore be thus contrasted : — 



Schuller and Wartha 

 Von Than 



By Regnault's 



formula. 

 . 34297 

 . 33928 



By Bosscha's 

 formula. 



34501 

 33928 



Julius Thomsen . . , 

 Favre and Silbermann 

 Andrews .... 



. 34207 

 . . 34408 

 . . 34028 



34308 

 34461 

 34141 



Mean . 



. . 34174 



34268 



That is, the average of these different determinations indicates 

 that by the combustion of 1 gramme of hydrogen and 7*98 

 grammes of oxygen to water, the gases and water produced 

 being at OS and 760 millims. throughout, the heat produced 

 would raise the temperature of 34,174 or 34,268 grammes of 

 water from 0° to 1° 0., according as Regnault's or Bosscha's 

 formula for the specific heat of water is used. It is noticeable 

 that the latter formula makes Schuller and Wartha's most 

 carefully made experiments appear abnormal, by showing a 

 much greater divergence, both from von Than's (made by 

 essentially the same method) and from the general average, 

 than is the case when Regnault's formula is employed ; and 



