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XIX. On Chlorine and Chlorate of Potassa. By JoHM 

 Murray, RL.S. M.G.S. M. W.S. ^c. <^c. 



To the Editors of the Philosophical Magazine and Journal. 



^ July 8, 1822. 



Genti-emex, — ferNCE my last communication I have made a 

 lew experiments in reference to the sensation of heat developed 

 by immersing the hand in chlorine. As far as can be ascertained 

 by this means, the increment of temperature certainly exceeds 

 100^ F. The temperature of the atmosphere being 66° F., 

 the thermometer was plunged into a volume of chlorine di- 

 luted with atmospheric air, and mto the same gas very pure, 

 and intense in its characteristic colour; but the thermometer 

 indicated no decided change, or at any rate the average of se- 

 veral experiments did not exceed '5 F. : — still the sensation of 

 heat on the skin was unequivocal. The ball of the thermo- 

 meter was then "wetted, but no perceptible change occurred. 

 In these experiments the vessels of chlorine were exposed at 

 top to atmospheric influence. The hand was passed up into 

 the chlorine over the shelf o( the pneumatic cistern, and a si- 

 milar increase of temperature experienced, while die thermo- 

 meter nndcr the same circumstances stood at 66^. 



I have said that this interesting property is not exclusively 

 peculiar to chlorine, and instanced nitrous gas when opened 

 in contact with atmospheric air. The temperature of the ex- 

 ternal air was 67^ F. and the thermometer rose in the nitrous 

 acid gas thus formed to 68"; in other experiments the exter- 

 nal temperature being 63-5. The thermometer rose to 65^ F. 

 But in another vessel, the ball of the instrument being moist- 

 ened, the mercury rose to 70° F., though the temperature felt 

 by immersion of the hand into this gas would be unhesitatingly 

 pronounced to be above 100° F. In the latter case the moist- 

 ened ball showed an increment over the instrument when dry, 

 but this refers entirely to their relative absorption by water, 

 and consequent condensation, — and has evidently nothing to 

 do with their reciprocal action on the epidermis. 



It is known that if sulphuric acid be passed through water 

 on the chlorate of potassa mixed with chips of phosphorus, the 

 curious and beautiful pluenomenon of combustion under water 

 ensues; but I find ihiitjlashcs of light are exhibited by merely 

 bringing the sulphuric acid in contact with the chlorate, al- 

 though })hosphorus is introduced. In this case chlorine is dis- 

 engaged, wliile the suj^ernatant fluid acquires a yellow tinge, 

 and in smell and other properties resembles a solution of 

 protoxide of chlorine, (rold-leaf does not dissolve in it, but 

 vegetable blue colours are discharged. 



I made 



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