1908] FREEMAN—DETERMINATION OF TRANSPIRATION I2I 
with vaselined absorbent cotton. The phosphorus pentoxid tubes 
used were 21°™ long and were fitted with glass stop-cocks and 
with suitable intake and outlet side tubes. ‘The P,O, was arranged 
in layers held apart by glass wool, so that the air could pass 
through it freely. Graduated aspirators fitted with stop-cocks at the 
base, and rubber stoppers at the top, would of course be more suitable, 
t 
Fic. 1 
but in the experiments I conducted 19. 5 liter bottles, fitted with two- 
pied tubber stoppers, for the intake tube and the outflow water 
Syphon, were used with satisfactory results. 
Wei begs the U-tubes are filled with P,O,, numbered and carefully 
up hg aspirator is filled with water and the whole apparatus “ 
the joint cing taken that. all the connections are properly made an 
S airtight. The stop-cocks in the U-tubes are turned off, so 
© nO Moisture may reach the P,O, between the time of weighing and 
