Combination of Bodies mth Oxygen. 333 



Alcohol and Oxygen. 



Tlie alcohol employed was perfectly pure. Its density at 

 15^ was 0-7959, and it was always redistilled IVoni a large 

 excess of pure lime immediately before being used. The 

 principal difficulty in examining the heat produced by the 

 combustion of this substance, was to complete all the prelimi- 

 nary arrangements alter its introduciion into the oxygen gas 

 so as to ignite it before any appreciable quantity had evapo- 

 rated. The shortest time in which I was able to accomplish 

 this was seven minutes ; but there can be little doubt that any 

 portion of alcohol which might rise into the state of vapour 

 during this time would become ignited along with the rest. 

 The duration of each experiment was five minutes. 



We have, therefore, for the heat evolved during the combi- 

 nation of — 



One gramme alcohol with oxygen . 6850 

 One gramme oxygen with alcohol . 3282 

 One litre oxygen with alcohol . . 4716 



In two experiments, Dulong found the heat produced during 

 tl>e combination of one litre of the vapour of alcohol with 

 oxygen to be 14310 and 14441 units. The corresponding 

 nuniber deduced from the preceding experiments is 14156. 



PhospJiorus and Oxygen. 



The inner vessel was filled with dry oxygen gas by displace- 

 ment. A shallow dish of thin Dresden porcelain was substi- 

 tuted for the platina cup, as platina enters into combination 

 with phosphorus at the elevated temperature at which the latter 

 burns in oxygen gas. The experiment occupied ten minutes, 

 from the slowness with which the porcelain dish gave out its 

 heat. 



