532 



Mr. G. Gore on 



Hot platinum became very feeble and very slowly positive 3° at 200° F., 

 by prolonged beat. The current declined on cooling.* 



No. 151. 6 oz. of water, containing about 300 grs. of very pure 

 fluoride of potassium, quite free from hydrofluoric acid. Solution 

 strongly alkaline. Hot platinum positive 15° at 200° F., and increased 

 to 18° by continued heat, and then began to decrease. (Compare No. 

 153.) 



No. 152. 6 oz. of water and 1 oz. of clear colourless crystals of pure 

 selenate of sodium. Hot platinum feebly positive 1° at 200° F., and 

 increased to If by continued heat. 



No. 153. 6 oz. of water and 565 grs. of fluoride of rubidium, per- 

 fectly free from hydrofluoric acid. Solution strongly alkaline. Hot 

 platinum positive 7° at 200° F., gradually increased to 10° by con- 

 tinued heat, and then slowly decreased. (Compare Nos. 149 and 151.) 



No. 154. 6 oz. of water and about J oz. of clear crystals of sulphate 

 of didymium.t Hot platinum positive 3° at 200° F., and increased 

 to by continued heat, and then began to decline. 



No. 155. The solution of sulphate of nickel of No. 55. Cold plati- 

 num feebly positive 1° at 100° F., and hot platinum positive 17° at 

 204° F. (Compare No. 55.) 



No. 156. 14 oz. of water and 2 oz. of crystals of chrome alum. Hot 

 platinum positive 17-^° at 170° F. No deflection at 104° F., and cold 

 platinum positive 2° at 198° F. No signs of corrosion of either pla- 

 tinum ribbon. 



No. 157. 6 oz. of water and ^ oz. of dry selenious acid. Hot pla- 

 tinum positive 9f° at 190° F., and 8J° at 200° F. No signs of 

 corrosion. 



No. 158. 7 oz. of water and 2 oz. of solid and colourless sulphate of 

 alumina. Cold platinum positive 35° at 200° F. 



No. 159. 7 oz. of water and 2\ oz. of dry crystals of green vitriol, 

 very slightly oxidized. Hot platinum positive 60° at 198° F. The 

 heated part of the solution became quite cloudy, and yielded an 

 ochreous deposit, showing a chemical change. 



No. 160. The solution of perchloride of iron of No. 77. Cold pla- 

 tinum positive 59° at 200° F. The needles returned to zero on cooling. 

 A very slight film of brown oxide was found on that electrode only 

 which had been heated, and probably increased its negative condition. 

 (Compare No. 77.) 



No. 161. The solution of permanganate of potassium of No. 94. 

 Hot platinum positive 17° at 140° F., the deflection diminished to at 

 190° F. On cooling the apparatus, the electrode which had not been 

 heated became positive, and when both electrodes were at 56° F. the 



* The bitartrates of rubidium aud caesium were prepared by Dr. H. Troinmsdorff, 

 of Erfurt. 



f Prepared by Dr. Troinmsdorff. 



