TO Scientific Intelligence. 



curve showing the relation between the deflections and the 

 electromotive force for any cell of the series is of the well- 

 known form. Accordingly, by means of cells of proper con- 

 struction, a simple and accurate series-electrometer may be 

 made ; such, also, that its range may be increased by increasing 

 the number of component cells. 



These experiments were made in the Sloane Laboratory of 

 Yale College, at the suggestion and under the direction of 

 Prof. A. W. Wright, to whom I expi'ess my thanks, for his 

 assistance and kindly encouragement. 



June 1, 1892. 



SCIENTIFIC INTELLIGENCE. 



I. Chemistry and Physics. 



1. On the Luminosity of Coal Gas Flames. — An investigation 

 has recently been made by Lewes as to the causes of the lumin- 

 osity in the flame of ordinary coal gas Previous researches have 

 proved beyond question the presence of solid particles in a lumin- 

 ous flame ; leaving the mode of decomposition by which they are 

 set free, for subsequent determination. Figures, obtained by the 

 analysis of the flame gases taken at different heights, show that 

 the hydrogen in the gas burns first, and that the saturated hydro- 

 carbons also undergo a rapid decrease in quantity ; while the 

 unsaturated hydrocarbons diminish only very slowly until the 

 top of the inner non-luminous zone has been reached, after which 

 they quickly disappear. Carbon monoxide also increases largely 

 up to the top of the luminous cone. Evidently this slow decrease 

 of the unsaturated hydrocarbons in the inner zone suggests that 

 the luminosity is due to these compounds, and especially to acet- 

 ylene. Experiment showed that in the interior of the luminous 

 flame the hydrocarbons begin at once to undergo decomposition 

 giving rise to acetylene which constitutes over 70 per cent of the • 

 unsaturated hydrocarbons present at the top of the inner non- 

 luminous zone. By means of a thermocouple it was found that 

 in a flat flame consuming T cu. ft. of gas per horn 1 , the temperature 

 at a half inch from the burner was 500° and at the commencement 

 of luminosity at the apex 1267°; while that at the center was 

 1014° rising to 1216° at the luminous edges. In the center of the 

 luminous portion the temperature was 1166°, while at the top of 

 the flame it was a maximum 1368°. Evidently then in the inner 

 non-luminous zone, the hydrocarbons heated up by the combus- 

 tion of the hydrogen and some of the methane, undergo certain 

 changes which result in their conversion into acetylene ; and this 

 being an endothermic compound, breaks up when a sufficient 

 temperature is attained. Owing however to the diluting action 



