218 E. W. Hiigard on Luminous Flames. 
» Mr. Stoney does not state what method he employed in inter- 
polating ; the correspondence between his values and my own is 
in general very close, though I employed the data obtained by 
Ditscheiner, in place of those of Angstrém.* 
Cambridge, Jan. Ist, 1869. 
Art. XVI.—On the condition of our knowledge of the Processes 
in Luminous Flames ; by Evcenr W. Hinearp. 
For more than half a century after Sir Humphrey Davy’ 
important investigations of the subject of flames, the expel 
ments and explanations of that eminent philosopher have passed, 
unchallenged and almost unchanged, into text-books and lec- 
ures. As regards luminous flames especially, he established 
the necessity of the presence of a solid incandescent body 
produce useful luminosity ; and in reference to the flames of 
hydrocarbons in particular, he suggested that the liberation of 
earbon in them was owing to the combustion of the hydroge? 
of the compound in advance of its carbon, the latter bemg 
eated to incandescence by an oxhydrogen flame, as it We®; 
and failing to be consumed until all the hydrogen was first 
ox 
stating at the same time that the prevalent opinion concerMMS 
* It is proper to state here, that since this paper was read before the Natie 
Academ, of Seiences, all the calculations oc se revised and many corre’. 
and alterations have been introduced. ‘The original title was, ‘‘ On the deter”? ” 
= a lengths by the method of comparison,” and a portion of the 
2 eee has already: ap with this title. This Journal for May, 1868- 
