782 



Mr. S. Gr. Lusby on the 



occurs. The temperatures were measured with a thermo- 

 couple whose members were platinum and platinum-rhodium. 

 The couple was standardized by the melting-points of very 

 small beads of various salts. The curves shown agree roughly 

 with some given by Marx [Joe. cit.), who sprayed salt vapours 

 into his flame, and thus got an evenly distributed source of 

 ionization, very different to the case in which a small salt 

 bead is placed under the upper electrode. On account of 

 this difference in the method of ionization, one would not 

 expect very close agreement of Marx's curves with those of 

 the author. Marx did not state the temperatures at which 

 his carves were taken, but merely indicated the appearance 

 of the electrodes — white-hot, red-hot, &c. 



(6) Velocity of the Flame Gases. 



The determination of the upward velocity of the gas was 

 made from a comparison of the pressures of the air and the 

 gas, and exact measurement of the volume of air used. For 

 this purpose a water-gauge was used to determine the 

 pressures of the gas and the air, or both combined, just 

 before entering the burner ; all three were read by a 

 cathetometer. The flow of air was obtained from the rate 

 of fall of the cylindrical holder which supplied it. 



(7) Results obtained. 

 In Table II. below are collected the final results obtained 

 Table II.— Mobilities of Positive Ions. 

 (a) Monovalent metals, (b) Divalent metals. 



I. 



II. 



III. 



IV. 



V. 



VI. 



Temp. 

 Abs. 



Minimum 

 Electric Force. 



Gas 

 Velocity. 



Mobility. 



Relative 

 Mobility. 



7c Q V£7 



100 

 93 

 86 

 83-5 

 81-5 



79 



77 



1950° 



1700 



1450 



1370 



1300 



1220 



>> 

 1150 



0-61 volts/cm. 



0-65 



071 



1-58 

 3-87 

 (a) 7-18 

 (6)9-16 

 (a) 17-0 

 (b) 3-3 



214 cm. /sec. 



210 



206 



181 



164 



183 



207 



350 

 320 

 290 

 115 

 42-5 



(a) 25-5 



(b) 20-5 



(a) 12-2 



(b) 6-2 



100 

 91-5 

 83 

 33 

 12-1 



(a) 7-3 



(b) 5-8 



(a) 3-5 



(b) 1-8 



