PREPARATIONS'45a-methylglucoside, together with the more soluble (3-methyl-glucoside: the amount of the latter is too small, however, towarrant attempted isolation.If difficulty is experienced in inducing the first crude crop of the a-glucosideto ciystallise, place a few drops of the solution on a watch-glass and exposefreely to the air, with occasional scratching: meanwhile keep the main volumeof the solution securely corked in the conical flask. After an interval of varyinglength (possibly several days), partial crystallisation occurs in the materialon the watch-glass. Then seed the solution with this material: crystallisationof the first main crop will rapidly follow.a-Methylglucoside responds to General Tests i and 2 for carbo-hydrates given on p. 366 (blackening with sulphuric acid, and Molisch'stest). Since, however, the glucoside does not contain a free aldehydichydroxyl group, it does not possess the reducing properties of glucoseitself. Confirm this by applying to pure a-methylglucoside Tests i and
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