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Whence this strange difference should arise, that the 

 "vapours of some mines catch fire with a spark, and 

 others only with a flame, is a question that we must be 

 content to leave in obscurity, till we know more of the 

 nature both of mineral vapour and fire. This only we 

 way observe, that gunpowder will fire with a spark, but 

 not with the flame of a candle: on the other hand, 

 spirits of wine will flame with a candle, but not with a 

 spark. But even here the cause of this difference re- 

 mains a secret. 



A like instance of the fatal nature of foul air hap- 

 pened at Boston, in New-England. Mr. Adams and 

 his servant being employed to repair a pump, uncovered 

 the well, and Mr. Adams went down by a rope; but he 

 had not gone six feet before he dropt suddenly without 

 speaking a word, to the upper part of the joint of the 

 pump, where being supported about a minute, and 

 breathing very short, he then fell to the bottom without 

 any signs of life. His servant hastily went down to 

 help his master ; but at the same distance from the top 

 was .struck, and without discovering any signs of distress, 

 fell to the bottom. The workmen prepared a third, 

 with a tackle about his waist, On his descent, he was 

 quickly speechless and senseless. Though he made no 

 sign, they drew him up. He was the very picture of 

 death, but by the use of proper means recovered. He 

 remembered nothing of what had passed. The other 

 bodies, when taken up, had all the marks of a violent 

 death. 



The vapour of fermenting liquors is equally extraor- 

 dinary in its effects. This vapour appears over the fer- 

 menting liquor as a fog in a meadow, but more fleecy. 

 It is heavier than air, and falls quick to the ground, and 

 disappears. Van Helmont calls it gas syivestre. Boer- 

 haave says, " There is nothing more surprizing in fer- 

 mentation than that spirit us sylvestris, war is there any 

 poison that I am acquainted with so subtle, swift, and 

 fetal. For if a very large vessel full of must, in the 



