CONGULATI0N OF MERCURY. 119 



vr. 



An Account of some Experiments on the Congelation of Mercury, 

 jij means of Ether. By Alexander Marcet, M. D. F.R.S. 



To Mr. Nicholson. 



Sir, 



MR. Leslie's new and ingenious mode of illustrating the Account of ^ 

 well known fact of the production of cold by evapora- m^'ho/of 6 * 

 tiori, by actually freezing water, in consequence of a rapid freezing, 

 process of vaporization from the water itself, has already be- 

 come a familar experiment. Water is placed over an open 

 vessel, containing sulphuric acid, and the whole being inclosed 

 within the receiver of an air pump, the water cools as the 

 exhaustion proceeds, and is ultimately converted into ice. I 

 have learnt also, that Mr. Leslie has succeeded in freezing mer- 

 cury by a similar process ; that is, by investing the bulb of a 

 mercurial thermometer with a thin coat of ice, and exposing 

 this to the joint effect of exhaustion and of sulphuric acid. 



After trying to repeat the last of these experiments, (an Mercury froz- 

 attempt in which I did not succeed ) I effected the congela- S^f ether*" 

 tion of mercury with great facility and quickness, simply by 

 substituting the evaporation of ether, instead of that of water, 

 in the process in question. I am not aware of having been 

 anticipated in this experiment j if I have, you will oblige me 

 by taking no notice of this letter j but, in the contrary case, I 

 shall thank you to give it a place in your Journal. 



The mode in which the experiment is made is this : a conical Method of 

 receiver, open at the top, is placed on the plate of the air pump, p^mcot.* 6 *" 

 and a mercurial thermometer is suspended within the receiver 

 through the aperture. This is done, like some of the well 

 known pneumatic experiments, by means of a brass plate per- 

 forated in its centre, and fitting the receiver air tight when laid 

 upon its open neck. The thermometer passes through this plate 

 to which it is carefully fitted by a leather adjustment, orsim- 

 ply by cork, secured with sealing wax j and it is so graduated, 

 that when its bulb is sunk a few inches within the receiver, the 

 stem rises externally through the plate, above which the scale 



begins 



