arabin

The action of gum solutions upon polarized light is interesting, especially in view of the fact that arabin is itself strongly lævo-rotatory [alpha] _ {D} = - 99°, while certain gums are distinctly dextro-rotatory.

Scientific American Supplement, No. 821, September 26, 1891 Various

Still further, if the insoluble residue of a Ghatti be the residual metarabin over and above that required to saturate the arabin, then it will be possible to dissolve this by the addition of more arabin in the form of ordinary gum arabic.

Scientific American Supplement, No. 821, September 26, 1891 Various

O'Sullivan obtained similar results with pure arabin.

Scientific American Supplement, No. 821, September 26, 1891 Various

Moreover, the solutions yielded by various Ghattis leaving insoluble matter behind would _be all of the same kind_, viz., a saturated solution of metarabin in arabin more or less diluted by water.

Scientific American Supplement, No. 821, September 26, 1891 Various

But the new hypothesis, and the experiments undertaken to confirm it, showed clearly that if the viscosity of a gum solution depends on the ratio of metarabin to arabin, then there is no absolute line of demarkation between a Ghatti and a gum arabic.

Scientific American Supplement, No. 821, September 26, 1891 Various

The yield of furfuraldehyde by the breaking down of arabin and metarabin was thought possibly to be of some value in differentiating the natural gums from one another, but we have not succeeded in obtaining results of much value.

Scientific American Supplement, No. 821, September 26, 1891 Various

For, let it be conceded that the solution of any Ghatti leaving an insoluble residue is a mixture of arabin and metarabin in the same ratio as our "maximum" solution, only more diluted with water, then from the found viscosity we obtain a point on the curve for dilution, which gives the percentage of dissolved matter.

Scientific American Supplement, No. 821, September 26, 1891 Various

This gum arabic may be regarded as nearly pure arabin (as calcium and potassium, etc., salt).

Scientific American Supplement, No. 821, September 26, 1891 Various

Hence it is evident that some other body besides arabin is present in the gum.

Scientific American Supplement, No. 821, September 26, 1891 Various

From observation of the general nature of the solutions of Ghatti gums, and from the fact that when allowed to stand portions of the apparently insoluble matter passed into solution, the hypothesis suggested itself that metarabin was soluble in arabin, although insoluble in cold water.

Scientific American Supplement, No. 821, September 26, 1891 Various