THE CARBOHYDRATES OF THE CACTI. 41 



this treatment the sugar solution was somewhat lighter in color. It was 

 subsequently treated with blood charcoal, which produced a light-yellow 

 solution. Prom 200 grams of the dry cactus material 25.25 grams sugar 

 gum were thus obtained. The solution was neutral towards litmus, reduced 

 Fehling's solution strongly, and was dextro-rotatory, [a]^ = +25.60. 



The mixture was tested for the presence of galactose in the usual manner 

 by treatment with nitric acid, sp. g. 1.15. No mucic acid, however, was 

 obtained, which indicated the absence of galactose. The acid solution thus 

 obtained from the oxidation with nitric acid was made alkaline with 

 potassium carbonate and then treated with an excess of acetic acid. On 

 standing, crystals of mono-potassium-saccharate separated out; this indi- 

 cated the presence of glucose in the sugar mixture. The presence of fructose 

 was established by means of the resorcin reaction. 



A portion of the sugar mixture was fermented with pure baker's yeast, 

 as has already been described. The residue from this process was a light- 

 yellow gum. In solution this evolved furfural freely when heated with 

 12 per cent sulphuric acid, and gave an intense violet-red coloration with 

 phlorogluzin. The reactions indicate the presence of a pentose sugar. The 

 specific rotation in a 1 dm. tube was 0]ff* = +22.1 with [a] = +2.05 

 and 9.26 grams in 100 c. c. of water. 1 The specific rotation of the solution 

 did not change after standing 24 hours. 



A portion of the sugar was treated with 2 parts of phenylhydrazine 

 hydrochloride and 3 parts of crystalline sodium acetate and heated for an 

 hour on the boiling water-bath. On cooling, a large quantity of bright 

 yellow phenylosazon separated out. This was recrystallized from water 

 and again from methyl alcohol. After drying in vacuum over sulphuric 

 acid, this melted with gas evolution at 159. 3 



Another portion of the sugar mixture was treated in aqueous solution 

 with an excess of bromine and powdered cadmium carbonate. After 24 

 hours the excess of bromine was driven off by heating on the water-bath, 

 the mixture was filtered from unchanged CdCO 3 , and the filtrate was 

 evaporated almost to dryness, and then 2 c. c. of alcohol was added thereto. 

 After several days the characteristic crystals separated out of the double salt 

 cadmium bromide xylonate, 8 



Cd(C 5 H 9 6 ) 2 CdBr 2 2H 2 O [] 2 D '= +6.9. 



From these results it is evident that the pentose sugar was 1-xylose. 



In the alcoholic extract of the dry plant material there would be present 

 of the carbohydrates only the disaccharides and monosaccharides. The 

 extract was prepared as has been previously described. The alcohol was 

 distilled off at reduced pressure. The residue contained, besides the sugars, 

 a large amount of chlorophyll and oil. To this was added water and some 



1 MAQUENNE, L. Les sucres et principaux derives, p. 350. a Ibid., p. 356. 



* BERT-BAND, M. G. Recherches sur quelques derives du xylose. Bull. Soc. Chim , m 



5, 546, 554, 1891. 

 NET, J. U. Ann. d. Chem., 403, 253, 1913. 



