334 



Prof. Spencer U. Pickering on Delicate 



II. 



Time. 



Reading. 







— 5 



water added. 





2 min. 



20-685 



5 „ 



20-76 



8 » 



20-855 



11 » 



20-94 



14 „ 



21-03 



Rate. 



•075 

 •095 

 •08 

 •09 



1 



mean 



•09. 



In this case the rate of heating is constant from the very 

 beginning : during the first three minutes it differs from the 

 mean of the other intervals by +*01 in Exp. 1 and by —'015 

 in Exp. 2, both of these quantities being well within the limits 

 of experimental error. 



III. 



Rate. 



•005 

 •09 ) 



•085 Vmean -093. 

 •105 J 



Time. 



Reading. 







o 



54 



Cold w^ater added. 





2 min. 



20-555 



5 „ 



20-56 



8 „ 



20-65 



11 „ 



20-735 



14 „ 



20-84 



Time. 



J 

 Reading. 







54 



Cold water added. 





2 min. 



19-45 



5 „ 



19-465 



8 „ 



19-555 



11 » 



19-645 



14 „ 



19-775 



IV. 



Rate. 



■015 

 ■09 

 •09 

 •13 



} 



mean 



103. 



In these two experiments, however, this is not so ; the rate 

 of heating (as registered) during the first interval is almost 

 nil, in each case exactly -088 less than the mean deduced 

 from the other intervals. Thus, when the column of mercury 

 rises to any temperature it will go on rising regularly after- 

 wards, indicating the rate of heating correctly, but when it 

 falls to that temperature a certain time elapses before it will 

 begin to rise afterwards ; although the mercury must be ex- 

 panding during this interval, the column is stationary, and 

 therefore the bulb must be expanding, and assuming a new 

 form. 



