630 Mr. A. Holt on the Decomposition of 



flame-tube pendulum as shown in fig. 3 and bent by tying 

 the two ends at (a) together. The thread joining the two 



Fig. 3. 



ends at (a) is burnt, and the spring thus set in motion. If 

 the band is geometrically and physically perfectly symmetrical, 

 the flames remain at rest *. 



Another case, where inertia plays a role, we have in the 

 so-called centrifugal force. If the flame-tube lying on the 

 table is turned about one end as centre, the flame at the 

 other end becomes large through the centrifugal force causing 

 an increase of the internal pressure at that end of the tube. 

 This effect is shown even if the motion is very slow. 



The experiments described above do not of course exhaust 

 the uses of the flame-tube, but merely serve as examples. 

 Physical Laboratories, 



Victoria University, Manchester. 



LIY. The Decomposition of Water- Vapour in contact with 

 Hot Platinum Wire. By Alfred Holt, Junr.f 



RATHER more than a year ago the author made several 

 attempts to estimate the extent of the dissociation of 

 water- vapour at high temperatures by heating a platinum 

 wire (by means of an electric current) in contact with 

 it at low pressures. The results were consistent among 

 themselves, but at high temperatures were decidedly lower 

 than those previously obtained by Nernst and Wartenberg 

 ( Gottinger JS T achr. 1905, p. 35) . The work was not published, 

 owing to the circumstance that some doubt arose as to whether 

 the numbers were a true measure of the dissociation of the 

 vapour at the temperature of the wire. 



* A cork pushed in between the prongs at (a) serves well enough for 

 holding the axle for the disk used in the last experiment. 

 t Communicated by the Author. 



