and that of Alcohol. 347 



A vacuum having been made in the boiler, the mercury 

 brought as nearly as poffible to a level in the two branches 

 /of the barometric tube, and the thermometer reduced to 

 zero by means of ice, the ice was removed, and a fire was 

 kindled, which was excited gently and with much equality, 

 in fuch a manner that the barometer pafled over about a 

 degree per minute. One perfon then flood by to obferve the 

 barometer, and another to obferve the thermometer, and 

 each kept a regifter from degree to degree of the preffurc 

 and correfponding temperatures; the preflure beine exprefied 

 by the height in (French) inches of the columns of mercury, 

 which rofe above the level in the long branch of the baro- 

 meter. 



It was exceedingly difficult to prevent either the introduc- 

 tion of air into the boiler, or the extra.vafa.tion of vapour, 

 according as the internal preffure was lefs or greater than 

 the weight of the atmoiphere : means, however, were found 

 to obviate thefe inconveniencies; but they are too long to be 

 detailed here, and mufl be read in the works before men- 

 tioned. 



The obfervations of the expanfive force of the fleam of 

 water furnifh no remits, proceeding from degree to degree 

 of the thermometer, and beginning at zero. Thefe refults 

 are contained in the annexed table, where the degrees of 

 preffure are expreffed in (French) inches of mercury, and" 

 the temperatures denoted according to Reaumur's fcale*. 



The experiments on the expanfive force of the fleam of 

 alcohol were made by the fame proceffes, and with the 

 fame apparatus, as thofe employed with the fleam of water. 

 The object of them, independently of their general utility in 

 phyfics, was to make known the relative expences which 

 would be occafioned by thefe fluids, when ufed to produce 

 moving forces in fleam -engines. This object of refearch is 



* For the convenience of our readers, we have added another column t» 

 fhe table, in which we have given the correfponding degrees of Fahren. 

 Jxeit's thermometer. Edit. 



both 



