420 EXPERIMENTAL INVESTIGATIONS. 



had, however, at one period made a rather careful investiga- 

 tion into some phenomena, suggested partly by a paper of 

 M. Donny's, published in 1843, and partly by my own experi- 

 ments on the decomposition of water by heat ; and although 

 this investigation did not lead to results as important as I at 

 the time anticipated, yet, as they seemed to add something to 

 our stock of knowledge, and may, it is hoped, form a start- 

 ing-point for important discoveries, I have ventured to bring 

 them forward on this occasion. 



The paper of M. Donny (' Memoires de 1' Academic Royale 

 de Bruxelles,' 1843) makes known the fact that in proportion 

 as water is deprived of air, the character of its ebullition 

 changes, becoming more and more abrupt, and boiling like 

 sulphuric acid with soubresauts, and that between each burst 

 of vapour the water reaches a temperature above its boil- 

 ing-point. To effect this, it is necessary that the water be 

 boiled in a tube with a narrow orifice, through which the 

 vapour issues ; if it be boiled in an open vessel, it continually 

 re-absorbs air and boils in the ordinary way. 



In my experiments on the decomposition of water by heat 

 I found that with the oxyhydrogen gas given off from ignited 

 platinum plunged into water, there was always a greater or less 

 quantity of nitrogen mixed ; this I could never entirely get 

 rid of, and I was thus led into a more careful examination of 

 the phenomenon of boiling water, and set before myself this 

 problem what will be the effect of heat on water perfectly 

 deprived of air or gas ? 



Two copper wires were placed parallel to each other 

 through the neck of a Florence flask, so as nearly to touch 

 the bottom ; joining the lower ends of these was a fine 

 platinum wire, ij inch long, and bent horizontally into 

 a curve. Distilled water, which had been well boiled, and 

 cooled under the receiver of an air-pump, was poured into 

 this flask, so as to fill about one-fourth of its capacity. It was 

 then placed under the receiver of an air-pump, and one of the 

 copper wires brought in contact with a metallic plate covering 

 the receiver, the other bent backwards over the neck of the 

 flask, and its end made to rest on the pump plate. By 

 this means, when the terminal wires from a voltaic battery 



