282 On the Volatility and Infiammaliltty 



easily happen. He should conceive, that the moment when an 

 explosion was most likely to take place would be that, when, 

 after the volatile oil had been detained by the mass standing to 

 cool all night, the fire was applied on the following morning, 

 before the pump was set to work. 



Willoughby and Clayton were then again called, and, in an- 

 swer to a question from the bench, stated, that when they first 

 perceived the fire breaking out from the premises of the plaintiffs, 

 there was no particular smell, nor did the flame appear of a dif- 

 ferent colour from that of ordinary fire. 



Here the evidence for the defendants closed. 



The jury afterwards intimated a wish to have some of the wit- 

 nesses recalled, in order to put certain questions to them on the 

 same subject. 



Mr. Faraday was then recalled, and examined by the foreman 

 of the jury. In his former evidence, he had spoken of an inflam- 

 mable vapotir, not of a volatile oil, as arising from the pipe. That 

 vapour would have burned more or less quietly in proportion to 

 the quantity of atmospheric air mixed with it. It required a 

 proportion of a fourteenth of gas to be explosive. This was the 

 vapour of oil at the temperature of 410. The explosion pro- 

 duced !)y it would not resemble the explosion of gunpowder. 

 The explosion of gunpowder was violent in proportion to the 

 volume of gas produced by the volume of gunpowder, combined 

 with the rapidity of the inflammation. The explosion of gases 

 might be generally considered in the same way — that was, the 

 proportion of the heated gas to the cold gas before it was fired. 

 The explosion would of course cause a rapid expansion. When 

 heated to a white heat, it occupied three or four times more space 

 than before, and it would expand to that extent in every direction. 

 All the vapour exploded would have its smell destroyed. The smell 

 belonged to the vapour, and not to its result or product. The pro- 

 of the exploded vapour would have other properties, would 

 new substances, and enter into new combinations with the 

 air into which it exploded. From the rough experiments he had 

 made, he thought that inflammable gas would have the same 

 effect as the oil. The smell, after the explosion, would depend 

 on the quantity of unconsumed vapour which might get about* 

 If the proportion of vapour were small, the flame would be blue; 

 if there was a great (juantity of vapour, and more confined, it 

 would burn brighter. The common gas-light was an instance 

 of continuous explosion with the greatest portion of vapour. 



Mr. Parkes was next recalled, and asked, by the same juror, 

 whether he differed from Mr. Faraday, and in what? He said he 

 did Jiot concur in all that Mr. Faraday had stated. He did not 



recollect 



