154 Artificial Cold. 



extremity of tlie beam, excepting where the machinery 

 stands. It may be used with much advantage in loading 

 or unloading ships, as it never interferes with their rigging. 

 It may be also extremely useful in building, where it ia 

 often necessary to place large stones on particular spots, 

 which is very difficult to accomplish with cranes on the 

 common construction. The whole apparatus is extremely 

 simple, and attended with little expense. A model of this 

 improved crane was exhibited in presence of the meeting. 



3. Notice respecting some Experiments on Alcohol. Ey 

 Mr. Hutton. 



For the conten'ts of this notice, see Mr. Hutton's paper 

 inserted at length in the present number, p. 130. 



XXIV. Intelligence mid Miscdlaneous Articles. 



ARTIFICIAL COLD. 



J. HE method employed by Professor Lesslie to produce 

 intense cold, by placing water over an open vessel contain- 

 ing sulphuric acid, and subjecting both, under the receiver 

 of a powerful air-pump, to quick exhaustion, is already 

 known to the public. The rapid vaporization from the 

 water quickly lowers the temperature of the residue, which 

 is ultimately converted into ice. By investing the bulb of 

 a mercurial thermometer with a thin coat of ice, and sub- 

 jecting this to exhaustion over sulphuric acid, the Professor 

 has also succeeded in freezing the mercury. 



By a communication from Dr. Marcet lo Mr. Nichol- 

 son * we learn that that gentleman has effected the conge- 

 lation of mercury by simply substituting the evaporation of 

 ether for that of water under the receiver of an air-pump. 

 For convenience, the graduated stem of the thermometer 

 should pass through a collar of leather in the plate that co- 

 vers the receiver. The bulb (which should descend a few 

 inches into the receiver) wrapped in a little cotton wool, or 

 in a little bag of fine fleecy hosiery, being dipped in ether, 

 the plate is then placed over the receiver, which is exhausted 

 as quickly as possible. In two or three minutes the tem- 

 perature is reduced to about 45° below 0, when the mercury 

 rapidly sinks and is speedily congealed. This experiment 

 succeeds whether sulphuric acid be inclosed in the receiver 

 or not, especially if the temperature of the apartment 

 be as low as 40° ; but it is more certain when the acid is 



* Nicholson's Journal, vol, xxxiv. p. 1 19. 



present. 



I 



