1919] 



SCHMITZ — STUDIES IN THE DECAY OF WOOD 



103 



cated by the table showing a similar increase in the amounts 

 of reducing substances present. 



The same procedure was followed with the extracts contain- 

 ing 0.5 per cent sulphuric acid. Table vi shows the dry- 

 weight of the total soluble substances after the weight of sul- 

 phuric acid had been deducted in each case. Each individual 

 watch glass was weighed immediately after taking out of the 

 oven, to avoid the error which might be caused by the acid 

 taking up atmospheric moisture. 



Table vn shows the total dry weight of the soluble sub- 

 stances present in the alkaline extracts after the amount of 

 sodium hydroxide in the residue had been deducted in each 



case. 



TABLE VII 



TOTAL DRY WEIGHT OF THE SOLUBLE SUBSTANCES IN THE ALKALINE EXTRACTS 



Flask no. 



42 

 43 

 44 



Interval of autoclaving 

 with dist. H 2 



Not autoclaved 



45 minutes 



Subsequent 

 autoclaving 

 after addi- 

 tion of alkali 



1 hour 

 1 hour 



Dry wt. of 

 residue 

 (gms.) 



. 0366 

 0.0312 

 0.0333 



Average 

 (gms.) 



0.0337 



25 

 26 

 27 



0.0384 

 0.0385 

 0.0377 



0.0382 



28* 

 29* 

 31 



11 hours 



1 hour 

 1 hour 



0.0100 

 . 0029 



. 0064 



^■■^ ^^^» 



0.0383 

 0.0415 

 0.0413 



^w^- ■ ^h^ ^^ ^^ ■*•- 



32 

 33 

 36 



21 hours 



. 0404 



* Portion of extract lost in oven 



Here again a slight increase is noted as the interval of auto- 

 claving with distilled water increased. 



Relative amounts of tannins present in the aqueous extracts. 

 — It could legitimately be contended that the increase in the 

 amounts of reducing substances present in the extracts which 

 reduce Fehling's solution might merely be due to prolonged 

 boiling extracting greater amounts of tannin. With this in 

 mind the aqueous extracts were treated with a solution of 

 ferric chloride and the intensity of the color taken as a crite- 



