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" Previously to describing myinventions, for some of which 

 I obtained patents for the three kingdoms and colonies, it will 

 be necessary to make some observations on the nature of those 

 substances which are concerned in the production of econo- 

 mical light. 



" Everyone knows that, although hydrogen is a chief com- 

 bustible element in all those flames which are used for the 

 purpose of illumination, its own flame, when the gas is per- 

 fectly pure, shows no light. In order to render it luminous 

 we have only to diffuse through it a small quantity of one or 

 other of the different forms of carbon or charcoal in a state of 

 very minute division. All our ordinary lights are derived from 

 combinations of hydrogen and carbon ; such are coal gas, oil 

 gas, resin gas, coal naphtha ; or from combinations of hydro- 

 gen, carbon, and oxygen, as oil, tallow, wax, spermaceti, 

 stearine of various kinds. 



"If the ratio of carbon to hydrogen be too small, the light 

 emitted from the combustible in burning will be pale and 

 feeble ; if the ratio of carbon be too large, the flame will be 

 yellow, or even brown and smoky. It is to the due adaptation 

 of the ratio of these two elements to the supply of oxygen, 

 whether contained in the combustible or in the air, that we 

 owe the production of the many brilliant lights which we 

 possess. 



" But the carbon and hydrogen need not be in that state of 

 combination in which we procure them. A hydrogen flame 

 may be rendered intensely luminous by the artificial supply 

 of carbonaceous matter; and a flame which is too pale and 

 feeble, such as that of hydrogen, bad coal gas, or of the oil or 

 stearine from the cocoa-nut, may be enriched to the greatest 

 intensity by merely presenting carbon in a proper state. 

 Carbon in such a state exists in all the volatile hydro-carbons, 

 as mineral naphtha, naphthaline, naphtha from coal tar, from 

 oil, from resin, or from Indian rubber ; it exists also in essen- 

 tial oils, and in spirit of turpentine or of resin, or of tar. 



