Dr. Marcet's Experiments on the Production, ^c, 253 



lint, and a few drops of the sulphureous liquor poured upon 

 it, the thermometer rapidly sinks from 60** to about o ; whilst 

 if a similar experiment be made with ether, or alcohol, under 

 the same circumstances, the temperature is reduced by the 

 ether to only about + 20^ and by the alcohol to about 50".* 

 The hygrometrical state of the atmosphere appears to have 

 some influence on these results. 



If the bulb of the thermometer, thus wetted with the sul- 

 phureous liquor, be introduced into the receiver of an air- 

 pump, (by means of a brass plate, as expressed in the annexed 



sketch, the plate fitting the receiver air tight when laid upon 

 its open neck), the thermometer sinks rapidly, as the ex- 



• I have also tried some experiments on the comparative elastic force of the vapour 



of these fluids, by introducing in succession a few drops of them, through mercury, 



into a torricellian tube ; and I obtained the following results : 



Depression Cold produced 

 Temper, of Mercury. 



- 66» - - 1,65 - 



- 66° - - 10,75 - 

 ' 66" - - 15,65 - 



It would appear, therefore, that the degree of volatility of a fluid, or of cold produced 

 by its evaporation, are far from bearing an exact proportion to the elastic force of its 



LI2 



Sp. Grav. 

 Pure alcohol - 0,806 - 

 Suiphuret of carbon 1,272 - 

 Rectified ether - 0,724 - 



by Evaporation. 



- from 68* to 52°. 



- from 68» to lo**. 

 firom 68° to z^.'^ 



