This section is from the book "A Treatise On Beverages or The Complete Practical Bottler", by Charles Herman Sulz. Also available from Amazon: A Treatise On Beverages.
"It fuses at about 392° F.; when fused upon platinum-foil or porcelain it emits a distinctly perceptible odor of oil of bitter almonds or essence of mirbane, and finally burns away without leaving a residue; a white residue would be evidence of the admixture of mineral adulterations. Four grains of saccharine should render a clear solution when agitated in a test-tube with two drachms of concentrated sulphuric acid. Upon gently heating this solution it should remain colorless; an ensuing brown or darker color would indicate an admixture of sugars or other organic adulterants. An additional test for the admixture of grape-sugar consists in dissolving four grains of the saccharine in one drachm of officinal liquor potassae, which should remain colorless upon gently heating for fifteen minutes. The same solution, when mixed with 1/2 drachm of Fehling's test solution and heated, should not render a brick-red turbidity; else grape or milk sugar are indicated.
"In order to examine cane-sugar for an admixture of saccharine which has been added to grape-sugar or glucose to enhance its sweetening properties, the following simple test is recommended: A test-tube, pointed and open at the lower end (a glass syringe answers best), containing about one fluid ounce, is closed at the lower orifice by a piece of cork or rubber, and is filled with the coarsely powdered sugar to be tested; the tube charged with the sugar is then filled with ether and is left standing for about one hour; then the lower orifice is opened and the ether allowed to flow off into a small porcelain capsule. Then, by placing the capsule over a sand-bath or other low fire the ether evaporates, leaving traces of saccharine behind, which is best and very perceptibly recognized by its extremely sweet taste. It may further be recognized by fusing in the capsule containing the ether residue, at a very gentle heat, a few grains of a mixture of six parts of sodium carbonate and one part of potassium nitrate; subsequently the fuse is heated to redness. The residue, when cold, is dissolved in a little distilled water, and the filtered solution is tested with a few drops of test-solution of barium chloride. An ensuing white turbidity of barium sulphate would prove the presence of saccharine, which forms at such incineration sulphuric acid, whilst no other sulphates possibly contained in the sugar would be extracted by ether".