272 



Wadsworth — Determination of Specific 



Then the maximum observed temperature 6 n at the end of 

 the second period will be less than the true maximum by an 



n 



amount A# = 2A 2 . To determine this quantity we make use 



i 

 of the same principle as before, viz : that the loss of tempera- 

 ture is proportional to the difference of temperature between 

 the calorimeter and external air, or 



A = k(*-/3) 

 = Kt-C 



(*) 



the equation of straight line cutting the A axis at a point, 

 — C, from the origin. 



The observations just given furnish data for drawing the 

 line of which (7) is the equation. Thus in fig. 1 lay off 

 OA=^, the mean temperature for the first interval, and AC, 

 proportional to A 1? the mean loss per interval, x, for same 

 period ; likewise lay off OB = ^ 3 , the mean temperature for the 

 third interval, and BD, proportional to A 3 , the corresponding 

 mean loss. Draw through D, C, the straight line DCm; this 

 will be the line required. Then it is evident that for any 

 other temperature, as some temperature m during the second 

 interval, the loss, A 2 , will be the ordinate to this line at a point 

 whose abscissa is 6 m . The total loss during the whole of the 

 interval = 2A 2 . This summation may be effected by a formula 

 derived from inspection of fig. 1. For 



SA a = A,' + V + 



+A 



= ab-\- cd+fe+ + ordinate at 



