144 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



of amber, as is supposed to have been the case in the Baltic 

 Sea. Schriften Naturfor. Gesellsch., Dantzig^ III., 2. 



LUMINOUS AND NON-LUMINOUS FLAMES. 



It was shown by Kriapp that flames may be rendered non- 

 luminous by the addition to the illuminating gas of nitrogen, 

 carbonic acid, or of air, and the effect was ascribed mainly to 

 the dilution of the gas. These experiments have been ex- 

 tended by Blackmann, by mixing air, oxygen, nitrogen, car- 

 bonic acid, carbonic oxide, and hydrogen, in turn, with the 

 gas, and noticing the effect upon aflame about \\ inches high. 

 The general results were as follows : The introduction of a 

 gas that does not take part in combustion increases the size 

 of the flame ; the ignition takes place on the exterior only, 

 and there is a definite degree of dilution at which combustion 

 ceases. On the addition of oxygen, on the contrary, an in- 

 terior zone of combustion manifests itself, the flame is short- 

 ened, and finally strikes down. While a flame can be render- 

 ed non-luminous by oxygen, the opposite effect can be pro- 

 duced by mixing this substance with the gas at the instant 

 of combustion, which may be done externally as well as in- 

 ternally by allowing the two to issue from separate openings, 

 and not affording time for uniform mixture, as in the Bunsen 

 burner. In such a flame, if the amount of oxygen be suffi- 

 cient for complete combustion, the air can take no important 

 part, and but a small amount of inert nitrogen can be present 

 to absorb the heat; the increased illuminating power must 

 be ascribed to the increased temperature resulting from more 

 concentrated combustion. The removal of the luminosity 

 by a gas that takes no part in combustion is due, on the con- 

 trary, to the extremely dilute condition in which the gas 

 enters into combustion, and the relatively small amount of 

 combustible matter that comes in contact with the oxygen 

 of the air. There is, however, a different explanation of the 

 non-luminous character of the flame of the Bunsen burner 

 found in the interior zone of combustion, in which a portion 

 of the illuminating gas is consumed, while another and larger 

 portion is converted into carbonic oxide and hydrogen, which 

 under ordinary conditions afford a non-luminous flame ; while 

 in the other zone of combustion there is a great dilution by 

 the products of combustion, and the nitrogen remaining from 



