W. G. MixteT — Heat of Comhustion of Hydrogen. 221 



mCy = 3'6, m = 9 grams and ~r- is a small correction amount- 



ing to about 6' calories when t is 18°. Thus 



Q = Q' + o-tvLt + 4044-9^ — 3-6j^^- ^ . (1) 



If Q^' is the heat given out when 7n grams of the mixed 

 gases are burned to liquid water between t^ and t, at the con- 

 stant pressure P, precisely similar reasoning shows that we 

 have 



Q = q" + mt-7nC^t^ (2) 



where Cp is the specific heat, at constant pressure, of the 

 mixed gases. 



^irst Series. 



Exjperirnent i.— Hydrogen, 110T'6^<= at 17-6° and 7674"^"^ ; 

 calculated weight 0'0944, observed 0*094:5 gram. Water and 

 water equivalent of calorimeter 1761*2 grams. 



Minutes. Temperature. • Temperature interval. 



15*73 17*498 — 15*73 + 0-005 = l-773° 



1 15-73 



2 ■ 15*73 Observed heat, 1761*2 XI •'773=:3122-6<^ 



3 17-50 Correction to calorie at 20° 2*2° 



4 17*498 



5 17*495 3124*8^ 



6 17*488 



7 17*485 



8 17*477 



Substituting numerical values in equation 1 we have 



^, 3124*8 



Q'= — — — - = 33102 



^ 0*0944 



o-tvLt = 102 



J "~ 



9t = 157 



—s-m^ = — 57 



Q =r 33702° 



404 



Experiment ^.— Gas, 1108°° at 18*3° and 756*8^^, weighing 

 0*0965 gram ; weight of like volume of hydrogen 0*09289 

 gram. Calculated amount of hydrogen present 0*09266 gram. 

 Water and water equivalent of calorimeter 1720*4: grams. 



