Dana on Flame. 401 



Art. XV. On the Effect of Vapour on Flame. By J. F. 



Dana, Chemical Assistant in Harvard University^ and 

 # Lecturer on Chemistry and Pharmacy in Dartmouth 



College, 



Cambridge, Mass. February b, 1819. 

 To Professor Silliman. 



DRAR SIR, 



^tlBOUT a year since I made some experiments on the effect 

 of steam on ignited bodies, with a view to learn the theory of 

 the action of the " American water-burner." These experi- 

 ments were published in an anonymous paper in the North 

 American Review, and have been published in London, with- 

 out an acknowledgment of their source. 



The effect of them concerning bodies is peculiar, and it 

 probably admits of more extensive application to the arts than 

 in the above named instrument alone. 



When a jet of steam, issuing from a small aperture, is 

 thrown on burning charcoal, the brightness is increased, if the 

 coal be held at the distance of four or five inches from the 

 pipe through which the steam passes ; but if the coal be held 

 nearer it is extinguished, a circular black spot first appears 

 where the steam is thrown on it. The steam in this case does 

 not appear to be decomposed, and the increased brightness of 

 the coal depends probably on a current of atmospheric air, 

 occasioned by the steam. But when a jet of steam, instead of 

 being thrown on a single coal, is made to pass into a charcoal 

 fire, the vividness of the combustion is increased, and the low 

 attenuated flame of coal is enlarged. 



When the wick of a common oil lamp is raised, so as to 

 give off large columns of smoke, and a jet of steam is thrown 

 into it, the brightness of the flame is increased, and no smoke 

 is thrown off. 



When spirits of turpentine is made to bum on a wick, the 

 light produced is dull and reddish, and a large quantity of thick 

 smoke is given off; but when a jet of steam is thrown into 



