Mr. P. E. Chase on Gravity and Magnetic Inclination. 329 



much fainter, and a dark space is observed above the burning 

 hydrogen surmounted by a flame of a light green colour. The 

 greenness is seen very well by employing a long test-tube, and 

 slowly bringing the mouth upwards as the hydrogen burns. 

 Mr. Waldie, in a paper "On Combustion and Flame/ J published 

 in the Philosophical Magazine for August 1838, remarks that 

 " one peculiarity in the flame of hydrogen must have been fre- 

 quently observed, namely, a green jet inside of the usual dark 

 central portion ; and when the flame is full, a dark central part 

 even in this.-" No explanation of this green colour is given by 

 the writer ; but it is, I believe, quite distinct from that which I 

 remarked. The appearance seen by Mr. Waldie I have frequently 

 noticed, and is probably caused by impurities in the gas. In 

 connexion with the hydrogen-flame, however, there is another 

 curious appearance, which possibly has often been observed — 

 namely, a kind of luminous stream to be seen stretching itself 

 some distance above the tip of the flame when the gas burns in 

 a darkened room. 



After the results detailed in the foregoing paper had been ob- 

 tained, it occurred to me that it would be well to try the effect of 

 bringing gases as well as solids and liquids into contact with the 

 hydrogen-flame. I tried carbonic acid, and found that the pre- 

 sence of this gas instantly changed the colour of burning hy- 

 drogen from a yellowish brown to a pale lilac, the whole of the 

 hydrogen-flame being here tinged. The same change in colour 

 may be seen by allowing the products of combustion from a 

 small and lightless gas- or alcohol-flame to pass through a 

 jet of burning hydrogen. A very small quantity of carbonic 

 acid imparted this colour to the hydrogen ; for it may be produced 

 by merely breathing on the flame. Beyond the fact just noticed, 

 I have as yet made no additional experiments : the explanation 

 of the phenomenon is therefore merely conjecture; but it is 

 possible this lilac-blue colour may be due to the hydrogen-flame 

 rendering incandescent the molecules of carbonic acid — or, more 

 probably, to a partial decomposition of the gas, and combustion 

 of the carbonic oxide. 



XLIV. On Gravity and Magnetic Inclination. 

 By Pliny Earle Chase, M.A. } S.P.A.S* 



A SOMEWHAT critical survey of the anomalies presented 

 by the magnetic inclination, to which I referred in a for- 

 mer article (Phil. Mag. S. 4. vol. xxx. p. 191), has given me 



* From Silliman's American Journal for September 1865. 



