The sugar gave a phenylosazone, melting ;it 154 — 155V. and easily 

 soluble in cold alcohol but not in water. The melting point of the sugar was 

 found to be 143 — 144 C C. The sugar under question is therefore xylose. 



Detection of Arabinose. 

 The mother liquor filtered off from the crystals of xylose was allowed to 

 evaporate slowly by itself. It did not show any sign of forming new crystals 

 after standing for a long time. The syrup gave a pentose reaction. Attempt 

 was then made to separate and detect arabinose by means of benzylphenyl- 

 hydrazin. The latter forms easily with arabinose a hydrazone, which is 

 hardly soluble in 75% alcohol, while xylose-hydrazone is easily soluble in the 

 same medium. 



3 grams of the syrup were dissolved in 9 grams of 75% alcohol, to which 

 a solution of 2 grams of benzylphenylhydrazin in 4 grams of absolute alcohol 

 was added and the mixture well shaken. After 3 hours, crystalline 

 precipitates were formed. They were separated by filtration with suction, 

 washed with a small amount of 75% alcohol and finally recrystallized from 

 95% alcohol. The light yellowish white product was dried over sulphuric 

 acid in vacuum. The melting point was found to be 1G9. - 169.5° C. 



0. 101 grams of the substance was dissolved in 25 c. c. of water and levc- 

 rotation of 0.3 on the scale was observed. 



The specific rotatory power is 



The observed specific rotatory power coincides with that of arabinose- 

 benzylphenylhydrazone. The small quantity of the hydrazone at hand did 

 not allow the isolation of arabinose. 



From the results obtained we may conclude as follows : 



1. The gummy substance in the flax stem consists largely of simple 

 pentosan, with a small amount of methyl pentosan. 



2. From the products of hydrolysis of the gummy substance, both xylose 

 and arabinose were identified. 



3. The pentosan of the gummy substance is, therefore, made up of both 



