RICHARDS. — HEATS OF COMBUSTION OF ORGANIC SUBSTANCES. 581 



After the combustion, the pressure of the gas in the bomb was 

 relieved and the bomb opened. The interior of the bomb and the 

 crucible were always inspected for any caramel or unburned sugar, but 

 in only two cases among the preliminary and rejected experiments was 

 any trace of caramel noted. The remaining gas was repeatedly ana- 

 lyzed after combustions of sugar for carbon monoxide, with negative 

 results. Any unburned iron wire was measured, and a correction sub- 

 tracted from the knoAvn heat of combustion for the original amount 

 used. The interior of the bomb and the crucible were rinsed with dis- 

 tilled water, and these washings, containing the nitric acid formed in 

 the combustion, were titrated with a solution of sodium hydroxide, 

 which was standardized so that one milliliter was equivalent to a 

 known rise in temperature of the calorimetric system. Corrections for 

 the burning of the iron wire and the formation of nitric acid were of 

 course subtracted from the observed rise in temperature. 



The data of a typical combustion of cane-sugar follow. 



Combustion No. 2. 



The weight of sugar (Sample A) taken was 1.5270 grams. The 

 calorimeter was adjusted at 2.55 o'clock. 



Temperature of jacket = 1.50*^ 

 Temperature of cover = 1.50 



The sugar was ignited at 3.08.10 o'clock, and the rapidly rising 

 temperature of the interior was equalled in the jackets and cover. 



Temperature of jacket = 3.11" 

 Temperature of cover = 3.19 



The observed rise of temperature was therefore 



3.117° - 1.496°= 1.621°. 



