RICHARDS. — HEATS OF COMBUSTION OF ORGANIC SUBSTANCES. 587 



Temperature of jacket = 2.31° 

 Temperature of cover =2.32" 



'I' 



Temperature of jacket = 4.10° 

 Temperature of cover =4.20° 



Observed rise of temperature = 4.118° — 2.330° = 1.788° 

 There was little if any odor in gas remaining in the bomb after com- 

 bustion. 11.0 centimeters of iron wire were burned, and 4.0 milliliters 

 of the solution of sodium hydrate were used. 



From the observed rise of temperature, 1.788°, the following correc- 

 tions must be subtracted : 



For error in graduation of thermometer = 

 For the combustion of 0.2073 gram sugar = 



" 11 cm. iron wire = 

 " nitrogen to nitric acid = 



Total, 





—0.001° 

 —0.218° 

 —0.011° 

 —0.003° 



-0.233° 



of 0.5840 gram of benzol raises the 

 = 1.555°, and 1 gram of benzol would 



Therefore the combustion 

 temperature 1.788° - 0.233° 

 raise the temperature 2.662°. 



In this result, 2.662°, mistakes of 0.001° in reading the initial and 

 final thermometric height would cause an error of almost 0.004°, if the 

 mistakes happened to be in opposite directions. On comparing a num- 

 ber of determinations, one would therefore expect to find an occasional 

 deviation from the mean as large as this ; but the mean should be much 

 more accurate, because in many determinations such accidents tend to 



