BY R. GREIG SMITH, 141 



were destroyed by the acid and removed as a partly soluble oil 

 or tar. But this will be seen more clearly as we proceed. 



A second portion of the natural gum was boiled for one hour 

 with 4% sulphuric acid, neutralised with barium carbonate and 

 precipitated with alcohol. The insoluble gum was boiled for an 

 hour with 5 % acid. From this no gum precipitable by alcohol 

 was obtained. Both these portions gave osazones with phenyl- 

 hydrazine. By treatment with ether followed by water the 

 precipitates were separated into portions which melted between 

 107° and 117° and into others which melted between 168° and 

 186°. Tn one of the latter portions, while the bulk melted at 

 186", the dust in the tube melted at 190'^, which suggested the 

 possible presence of galactosazone. Its actual presence, however, 

 could not be proved. The portions with the low melting points 

 were largely destroyed when evaporated with dilute acetic acid. 



In view of the unsatisfactory results which had been obtained 

 a third portion was hydrolysed. The gum was dissolved in the 

 autoclave and coagulated with alcohol. The coagulum after 

 being dissolved in water and evaporated, was tested with Fehling's 

 solution; no reduction was obtained. The gum was boiled 

 under an aerial condenser for an hour with 0*5 % sulphuric acid. 

 The neutralised and evaporated solution was treated with alcohol 

 and filtered. The insoluble gum was boiled with 1 % acid for an 

 hour and treated as described. The gum unacted upon was 

 boiled with 5 % acid for an hour, wdien only a trace of unattacked 

 gum remained. Thus there were obtained three solutions of 

 hydrolysed gum, and all reduced Fehling's solution. I shall 

 describe the investigation of the products of hydrolysis with 

 some detail because similar reducing substances were obtained 

 from the gum of linseed mucilage. The reducing solutions were 

 treated while on the water-bath with phenylhydrazine mixture 

 containing of the base 1 part, glacial acetic acid 1 part, glacial 

 acetic acid saturated with sodium acetate 1 part, water 1 part. 

 The acetate was added because potassium chloride was sometimes 

 used to flocculate the milk}'' solutions of the gum. Any tarrj' 

 matter that formed during the heating on the water-bath was 



