Mr. Ivory on the Elastic Force of Steam 



In this Table the column marked t contains the temperature 

 beginning at 50°, and increasing continually by 20° as far as 

 Dr. Ure's Table enables us to go. In the column on the left 

 are placed the indices which denote the number of intervals 

 of 20°. If T denote any temperatui'e indefinitely, and x the 

 corresponding index, we have, 



■r-50 



X = . 



'20 



The next column, marked e, contains the elasticities, or the 

 tensions of the steam, in inches of mercury, taken from Dr. 

 Ure's Table. Immediately after are placed the logarithms 

 of the elasticities estimated in parts of an atmosphere of 30 

 inches. Then follows the temperatures of the steam reckoned 

 from the boiling point, which are negative for all cases below 

 212°, and positive for all cases above it. In the next column 

 are placed the quotients of the numbers in the two last columns. 



These quotients are irregular near 212°; because as — ap- 

 proaches to unit, its logarithm varying rapidly for any change 

 in e, the errors of observation have a great influence in this 

 part of the Table. It is remarkable however that the num- 

 bers in this column form a series continually decreasing. 

 Supposing the Table to be continued, would the numbers go 

 on decreasing to a fixed limit ? Or, would they decrease to 

 a minimum, and then increase again? The differences of the 

 quotients are placed in the next column. These differences 

 are extremely irregular, and, taken directly, seem to furnish 



no 



