sm 



Daniell ow a new Hygrometer . 



Table I. — continued. 



Mr. Dalton, in his valuable Essay before referred to, has de- 

 tailed the results of a laborious series of experiments, by which 

 he ascertained, with precision, the force of vapour from water, 

 at every degree between its freezing and boiling points ; and 

 has extended the observations by an ingenious calculation to 

 every temperature from that of the congelation of mercury to 

 325° of Fahrenheit's sCale. These results, as faf as is 

 necessary to the present purpose, I have adopted, and the 

 second column of the table exhibits the force of aqueous 

 vapour, in inches of mercury at the temperature opposed 

 to it in the first column. Upoa these two data, namely, 

 the force and temperature of the vapour, are founded the 

 calculations, which have furnished me with the series of 

 the third column, which contains the weight in grains of a 

 cubic foot of the vapouif at the corresponding temperature and 

 pressure. The method of proceeding is this: Steam at 212°, 

 and under a pressure of 30 inches of mercury, is, as nearly a» 

 possible 1700 times lighter thaii an eq\ial bulk of water. A 



