Prof. Buff on the Electrical Properties of Flame. 145 



Group 6, with D predominating. — Crystals elongated verti- 

 cally. A very rare configuration principally exhibited by a few 

 crystals from Siberia, and from the Siebenbirgen district. 



The most common forms of sulphate of baryta are P, |A, and 

 E. D, 0, and L are also of frequent occurrence, but they are 

 comparatively of small size. L is more common than the back 

 and front monaxial form M : the two are not often found in the 

 same combination. 



XXII. On the Electrical Properties of Flame. By H. Buff, 

 Professor of Natural Philosophy in the University of Giessen*. 



PROFESSOR BUFF commences his memoir with a review 

 of the divergent notions at present existing as to the elec- 

 tricity of flame ; Becquerel finds electric opposition in all direc- 

 tions in flame, which depends upon the difference of the tem- 

 perature of the metals immersed in it ; Pouillet recognises a 

 motion of electricity only from the interior to the exterior, and 

 hence also from the base to the summit of the flame ; according 

 to Hankelf, however, the motion of the electric fluid, at least in 

 flames obtained by the ignition of spirit, is exactly opposite, and 

 independent of the temperature of the immersed conductor. 

 To solve these contradictions was the object of the present in- 

 vestigation . 



Two small strips of platinum were introduced into a glass tube 

 closed at one end; they were separated by an interval of 1*5 

 line of air. The air within the tube could not be heated to a 

 degree sufficient to permit the electricity of two of DanielFs cells 

 to pass through it. When the glass became soft by heating, and 

 both pieces of platinum were permitted to touch it, a strong 

 deflection of the needle of a galvanometer was the consequence. 



A porcelain tube two feet long and six lines wide was encom- 

 passed with glowing coals, and air was drawn slowly through it ; 

 this air could not be heated so as to allow the passage of the 

 electricity from the source above mentioned, although the two 

 platinum wires sunk in the air were less than a line apart, and 

 were glowing red. 



A metal web was placed over the flame of a spirit-lamp ; the 

 flame did not pass through ; over the web the platinum strips 

 were held a line apart — there was no passage of electricity. 



The galvanometer used in these experiments was extremely 

 sensitive When two persons who were connected simply by the 



* Avnalen der Vkemie und Fharmacie, vol. lxxx. S. 1. 

 t Pl.il. Blag., 8.4. vol.ii. p.642. 



Phil. May. S. 1, Vol. 3. No. 10. Feb. 1852. L 



