Chemical Effects of Caloric, Sfc. 85 



that when we set the spirit of wine on fire, the 

 flame continues clear without smoke till the last 

 drop of the fluid is consumed, and nothing re- 

 mains in the vessel. But here is a deception, 

 for a great quantity of matter escapes from the 

 spirit that evades the cognizance of our senses. 

 This may be proved by placing a hollow ves- 

 sel over the flame, which confining and cool- 

 ing it, the internal surface of the vessel will be 

 bedew r ed with a watery moisture. Some have 

 imagined it to be one-third of the spirit, others 

 one-half, and others three-fourths : the fact is, 

 however, that highly rectified spirit affords ra- 

 ther more than its own weight of water by com- 

 bustion. 



The reason we do not see the watery part eva- 

 porate is, that the fluid is converted into vapour 

 in so gradual a manner, that it is impossible to 

 discover it by our senses, unless we use those 

 means of collecting and condensing it. Sulphur 

 is another substance which former chemists ima- 

 gined was consumed or destroyed wholly by fire; 

 but by an easy experiment we find that a quan- 

 tity of acid is thrown off during the combustion, 

 which is equal in weight to the substance which 

 produced it. 



The theory of combustion is now indeed as 

 well understood as most facts in chemistry. Com- 

 bustible bodies are such as will readily combine 

 with oxygen gas ; consequently, when any such 



