340 On the Chemical Evidence 



flammable at 310°." These statements convince me that there 

 must either have been some mistake as to the nature of the oil 

 that was employed, or a part of the mercury must have escaped 

 from the thermometer by an accident, or by distillation, in the 

 intense heat to which oil may be subjected, as we are told the 

 thermometer was open at the top. It is certainly not usual to 

 employ such thermometers in any experiments that require ac- 

 curacy. Mr. Wilkinson also tells us, " that the thermometer was 

 proved by hot water before it was put into the oil ;" but I should 

 be glad to be informed, how the a'^uracy of a thermometer, 

 which is designed to measure temperatures above 212°, can be 

 determined by hot water. 



Mr. Michael Faraday, Assistant in the Laboratory of the 

 Royal Institution, stated, that " he heated oil in an open pan, 

 and found the vapour combustible on the surface of the oil at 

 490°, and that it will burn constantly, the temperature being 

 kept up ; that he has distilled whale-oil, and produced naphtha 

 from it ; that he had produced it at a lower temperature from 

 oil that had been heated to 360° for twenty-four successive 

 days, than he could from fresh oil ; that the vapour of the dis- 

 tilled oil is heavier than the atmosphere, and so is the vapour 

 produced from the naphtha ; that the vessel in which the oil 

 was boiled had a tube rising two feet above it ; that he caught 

 the vapour issuing from the pipe in a pewter vessel, and when a 

 light was applied to it, it inflamed throughout the capacity of 

 the vessel, and that if the steam-bin at the sugar-house had 

 been filled with such vapour, he should not be surprised if it 

 did inflame." On being asked, if any experiment was made to 

 see what effect was produced on the oil itself, he replied, 

 " they rose the oil to 410°, and the emission of vapour was 

 continued ; the heat was then continued to get a stronger va- 

 pour, but instead of that we got the oil out." When asked at 

 what degree it had then arrived ? he answered, " During the 

 boiling, and when we began to look at things, the temperature 

 was 460°." He went on to say, " it passed out in jerks, it was 

 thrown out by a rapid concussion in the boiler, the formation 



