BY R. GREIG SMITH. 343 



By using aluminium hydrate a claritication of the gummy 

 solutions was effected, and although this reagent also removed 

 some of the gum, yet the clear solutions were still viscous. These 

 solutions were neutral to litmus paper, and upon being tested 

 were found to be inactive to polarised light. 



The slime thus obtained in saccharose solutions, and therefore 

 free from any admixture with agar, was hydrolysed with dilute 

 sulphuric acid after all saccharose and reducing sugars had been 

 eliminated. The crude osazone was extracted with ether and 

 then dissolved in 85 % alcohol to remove an unhydrolysed product. 

 The osazone obtained upon evaporating the alcoholic solution to 

 dryness melted at 181-1 82*^ and appeared microscopically to con- 

 sist of two kinds of crystalline groups, one being pale yellow, the 

 other dark yellow in colour. Hot water extracted a constituent 

 which upon evaporation appeared as a brown deposit and which 

 melted at 158-159°, the melting point of arabinosazone. Thus 

 arabinose is proved to be a constituent of the hydi-olysed carbo- 

 hydrate and was not in the former tests derived from the agar 

 upon which the slime was produced. 



The gum is one of those soluble kinds which readilv become 

 altered to an insoluble moditication upon drying or bv the action 

 of dehydrating agents such as alcohol. The insoluble modifica- 

 tion is soluble in dilute acid and insoluble in dilute alkali. It is 

 therefore akin, so far as the solubilit}- is concerned, to the met- 

 arabin and pararabin gums. But unlike these gums, it is not 

 readily converted from the insoluble to the soluble moditication, 

 and cannot therefore be of any direct commercial importance. 



The bacterium undoubtedly contributes a part of the natural 

 gum of the plants in the tissues of wliich it occurs, but the part 

 is so small as to be almost negligeable. I obtained some almond 

 gum from Mr. Stoward, of Adelaide, and removed the soluble 

 arabin by soaking the gum in water and filtering. The insoluble 

 metarabin was dissolved by heating under pressure, and after 

 acidification with hydrochloric acid the gum acids were precipi- 

 tated with alcohol. Tlie acid alcoholic sohitioii was then neutral- 



