262 On the Volatility and Inflammability 



ing often heated. In all new oil there was a certain portion of 

 water, and of course it did not inflame quite so soon as old oil 

 which had been frequently heated, and had lost some of those 

 aqueous particles. The difference in that respect could not, 

 however, be considerable. It was quite clear, from the model 

 then before tliem, that if any inflammable gas had been generated 

 in the machine, it would have escaped through the leaden pipe 

 which led into the steam -vent. 



Cross-examined. — Experiments had been tried for the pur- 

 pose of ascertaining whether oil changed its properties in conse- 

 quence of constant use, A quantity of old oil was put into one 

 retort, and an equal quantity of new into another. Very httle 

 difference was found in heating them to the pitch at which gas 

 was produced. In heating oil for refining sugar^ he saw no dan- 

 ger whatever. The process of boiling sugar in the old way was 

 extremely dangerous. 



Mr. Samuel Parkes stated that he was an experimental and 

 practical chemist. He had attended to the model of the machine, 

 and to the manner in which the process of refining sugar was 

 carried on ; and he considered that the old mode of boiling sugar, 

 for the purpose of refining, was more dangerous than the present. 

 He had no hesitation in saying, that it v;as attended with much, 

 less danger. The danger arose from the chance of the fire com- 

 ing in contact with the sugar-pan. Witness attended through- 

 out to Mr. Wilson's examination, and, with certain exceptions, 

 agreed in the correctness of what he stated. He did not, how- 

 ever, agree with him in what he said on the subject of the gas of 

 old oil. He had mixed five ounces of sugar with a proper pro- 

 portion of water ; and when he had increased the heat to 230 de- 

 grees, the sugar and water boiled rapidly. The thermometer 

 then remained stationary for a time, but it afterwards moved 

 slowly upwards to 340 degrees. A species of gas was then pro- 

 duced ; but, when the heat was raised to 370 degrees, the gas 

 burned with a strong and permanent flame. When a heat of 590 

 degrees was applied to old oil, it produced an inflammable, but 

 not a permanent inflammable gas. The lowest temperature at 

 which inflammable gas was produced from oil was 586; but it 

 was not permanent inflammable gas. What he meant by a non- 

 permanent inflan.mable gas was, a gas which would light if a 

 match were applied to it, but which would go out when the match 

 was removed. When the heat was raised to 600 degrees, a gas 

 was produced from oil, which, if touched with a match, lighted 

 up, and continued to burn. That was the lowest temperature at 

 which permanent inflammable gas was produced from oil. When 

 a chemist went on applying powerful heatj the difficulty of raising 



it 



