Practical physiological chemistry : a book designed for use in courses in practical physiological chemistry in schools of medicine and of science . t loss of fluid by bumping. Add 4-5 dropsof sodium hydroxide (sp. gr. ), being certain that thefluid in the test-tube remains acid, heat the mixture againfor a moment and then cool the contents of the tube. Ordi-narily the crystals form at once, especially if the sugar solu-tion possesses a low specific gravity. If they do not appearimmediately allow the tube to stand at least 20 minutes beforedeciding upon the absence of sugar. Examine the cry
Practical physiological chemistry : a book designed for use in courses in practical physiological chemistry in schools of medicine and of science . t loss of fluid by bumping. Add 4-5 dropsof sodium hydroxide (sp. gr. ), being certain that thefluid in the test-tube remains acid, heat the mixture againfor a moment and then cool the contents of the tube. Ordi-narily the crystals form at once, especially if the sugar solu-tion possesses a low specific gravity. If they do not appearimmediately allow the tube to stand at least 20 minutes beforedeciding upon the absence of sugar. Examine the crystals under the microscope and comparethem with those shown in Plate III, opposite page 5. 5. Precipitation by Alcohol.—To 10 of 95 per centalcohol add about 2 of dextrose solution. Compare theresult with that obtained under Dextrin, 7, page 28. 6. Iodine Test.—Make the regular iodine test as givenunder Starch, 5, page 24, and compare this result with theresults obtained with starch and with dextrin. 7. Diffusibility of Dextrose.—Test the diffusibility of dex-trose solution through animal membrane, or parchment paper, Fig. Dialyzixg Apparatus for Students Use. making a dialyzer like one of the models shown in Fig. 1,above. MONOSACCHARIDES. 7 8. Moores Test.—To 2 3 of sugar solution in a ;tube add an equal volume of concentrated KMI r NaOH,and boil. The solution darkens and finally assumes a browncolor. This is an exceedingly crude tesl and is of little prac-tical value. 9. Reduction Tests.—To their aldehyde or ketone structine many sugars owe the property of readily reducing alka-line solutions of the oxides of metals like copper,bismuth andmercury; they also possess the property of reducing ammo-niacal silver solutions with the separation of metallic this pmperty of reduction the most widely used testsfor sugars are based. When whitish-blue cupric hydroxidein suspension in an alkaline liquid is heated it is convertedinto insoluble black
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