[Vol. 6 



98 



ANNALS OF THE MISSOURI BOTANICAL GARDEN 



TABLE I 



COLOR CHANGES INDUCED BY AUTOCLAVING DOUGLAS FIR AND WESTERN HEM 



LOCK SAWDUST FOR VARIOUS INTERVALS 



Interval of 

 autoclaving 



Control (not autoclaved) 



45 minutes 



10 hours 



20 hours 



Color 



Douglas fir 



Antimony-yellow 

 Cinnamon-buff 

 Cinnamon 

 Mikado-brown 



Western hemlock 



Cinnamon-buff 

 Sayal-brown 

 Snuff-brown 

 Natural brown 



is not entirely known but it is quite evident that some changes 

 must occur due to the prolonged heating. 



Relative amounts of reducing substances in the aqueous ex- 

 tracts after autoclaving Douglas fir saivdust. — Into each of 

 fifteen thoroughly cleaned 125-cc. Erlenmeyer flasks equal 

 amounts, 2.000 gms., of fine Douglas fir sawdust were placed. 

 The sawdust was prepared from the heart-wood in the fol- 

 lowing manner: Large pieces were sawed in the direction of 



fine to coarse sawdust 



This 



then ground in a bone grinder until a conmarativelv fine 



mixture 



obtained 



The 



lust 



d 



weight in a hot-air oven at a temperature of 85° C. and then 

 allowed to stand uncovered in the laboratory for twenty-four 

 hours. It was assumed that a fairly constant weight would 

 be attained during that time, the amount of moisture taken 

 up depending on the relative humidity of the air and the tem- 

 perature. This procedure was followed rather than that of 

 taking equal amounts of thoroughly dry sawdust, since it was 

 found that a considerable fluctuation in weight took Dlace dur- 



moistur 



of weighing due to absorption of atmosph 



To each of the flasks 25 cc. of distilled water were added 

 and each flask and contents weighed, as before, to the nearesi 

 0.1 gm., in order that the flasks might be restored to their oris- 



ght after autoclaving 



Three of the fifteen flasks 



not autoclaved, three were autoclaved 45 minutes, three 1 hour 

 and 45 minutes, three 11 hours, and three 21 hours. After 

 removal of the last set of flasks from the autoclave the contents 

 of all the flasks were emptied into graduate cylinders and the 



brought ud to 



The 



