DETERMINATION OF TRANSPIRING POWER 



179 



table of ratios furnished by Livingston and 8hreve, 10 it may be 

 calculated that the time for the slip would be 31.9 seconds if air 

 temperature is used, or 31.2 seconds if the temperature of the 



TABLE 4 



Temperatures of tripartite slips lying over a porous evaporating surface compared 



with the temperature of (he air in. the iunm diate ricin.it ij. Readings taken 



in a small closed room 



Temperature air by mercury thermometer . . . 

 Temperature slip by thermo-couple 



Temperature air by mercury thermometer . . . 

 Temperature slip by thermo-couple 



Temperature air by mercury thermometer . . . 

 Temperature slip by thermo-couple 



Temperature air by mercury thermometer . . . 

 Temperature slip by thermo-couple 



Temperature air by mercury thermometer . . . 

 Temperature slip by thermo-couple 



NUM- 

 BER 

 OF SLIP 

 USED 



12 



16 



18 



25 



48 



TABLE 5 

 Calculated time for color change to be completed at 20°C. on various cobalt slips 

 using (A) the temperature of the air as read by a mercury thermometer, and (B) 

 the temperature of the slip as determined by the thermo-couple 



slip is used. The times for the other slips were calculated in the 

 same way. The effect of these differences in the results of the 

 standardization, upon the index of transpiring power is shown 



10 Livingston and Shreve, loc. cit. p. 305. 1916. 



