162 BACTERIA AND THE GUM OF LINSEED MUCILAGE, 



According to Andes,* Linseed mucilage is dextrorotatory and 

 insoluble in Schweitzer's reagent (ammonio-copper hydrate). 

 AVhen boiled with 1*25% sulphuric acid it is converted into 

 cellulose and a gum. Further boiling produces a sugar. The 

 gum is indifferent to iodine and is dextrorotatory. The most 

 recent work upon the chemistry of the slime is that of Hilger,t 

 who found that the crude slime after extraction with hydro- 

 chloric acid to remove the mineral constituents was dextroro- 

 tatory. The concentrated aqueous solution gave insoluble com- 

 pounds w4th copper sulphate, Fehling's solution, mercury salts 

 and basic lead acetate; neutral lead acetate formed a compound 

 only upon warming. The purified slime was starch-free and con- 

 tained, besides a little ash, about half a per cent, of cellulose. 

 With nitric acid it yielded mucic acid, and with hydrochloric 

 acid, furfural. From the analysis and the estimation of the 

 amounts of mucic acid and furfural he devised the formula for 

 the gum 2(CoHio05).2(C.H80J. When hydrolysed with 

 0"5-l % sulphuric acid, it yielded a mixture of galactose, dextrose, 

 arabinose and xylose as shown by a method devised by him for 

 the detection of these sugars. 



I have prepared many samples of the gum from the mucilage 

 by soaking the whole seed as well as the meal overnight in water 

 and pressing the mucilage through calico and thereafter separat- 

 ing the cellulose by subjecting the mucilage, acidified preferably 

 with sulphuric acid, to a pressure of three atmospheres in the 

 autoclave. The cellulose was thus separated, though not so easily 

 as could have been wished, and the solution of gum was pre- 

 cipitated with alcohol and afterwards made into a thick mucilage 

 with water. The tests were made with drops of the mucilage 

 and drops of reagent. The reactions of the several samples, 

 purchased from different stores in Sydney, are given in tabular 

 form. 



* Gummi Arabicum und dessen Surrogate, Leipzig, 1896, p. 162. 

 t Beriehte der Deut. Gesell. 36, 3197. 



