of Flame and Gases. 417 



seem impossible that sufficient power might cause their sepa- 

 ration from a state of mixture. 



In the course of these experiments I subjected several of 

 the gases to heat, to ascertain whether they generally under- 

 went the same exaltation of their diamagnetic power which oc- 

 curred with common air. For this purpose a helix of platina 

 wire was placed in the mouth of the delivering tube, which 

 itself was placed below the magnetic axis between the poles. 

 The helix could be raised to any temperature by a little vol- 

 taic battery, and any gas could be sent through it and upwards 

 across the magnetic field by means of the Woulf's bottle ap- 

 paratus already described. It was easy to ascertain whether 

 the gas went directly up between the poles, or, on making the 

 magnet, left that direction and formed two equatorial side- 

 streams, either by the sensation on the finger, or by a spiral 

 thermoscope formed of a compound lamina of platinum and 

 silver placed in a tube above. In every case the hot gas was 

 diamagnetic in the air, and I think far more so than if the gas 

 had been at common temperatures. The gases tried were as 

 follows : oxygen, nitrogen, hydrogen, nitrous oxide, carbonic 

 acid, muriatic acid, ammonia, coal-gas, olefiant gas. 



But as in these experiments the surrounding air would, of 

 necessity, mingle with the gas first heated, and so form, in 

 fact, a part of the heated stream, I arranged the platinum 

 helix so that I could heat it in a given gas, and thus compare 

 the same gas at different temperatures with itself. 



A stream of hot oxygen in cold oxygen was powerfully 

 diamagnetic. The effect and its degree may be judged of by 

 the following circumstances. When the platinum helix below 

 the axial line was ignited, the effect of heat on the indicating 

 compound spiral, placed in a tube over the axial line, was 

 such as to cause its lower extremity to pass through one and 

 a half revolutions, or 54-0°: when the magnetic force was 

 rendered active, the spiral returned through all these degrees 

 to its first position, as if the ignited helix below had been 

 lowered to the common temperature or taken away; and, yet 

 in respect of it, nothing had been changed. On rendering 

 the magnet inactive, the current of hot oxygen instantly re- 

 sumed its perpendicular course and affected the thermoscope 

 as before. 



On experimenting with carbonic acid, it was found that 

 hot carbonic acid was diamagnetic to cold carbonic acid ; and 

 the effects were apparently as great in amount as in oxygen. 



On making the same arrangement in hydrogen, I failed to 

 obtain any result regarding the relation of the hot and cold 

 gas, for this reason : — that 1 could not, in any case, either 



F/iil. Mag, S. 3. Vol. 31. No. 210. Dec, 1847. 2 E 



