4398. Pettenkofer's Test for Bile in Urine, etc.

4398.    Pettenkofer's Test for Bile in Urine, etc.. Put a small quantity of the suspected liquid into a test-tube, and add to it, drop by drop, strong sulphuric acid till it becomes warm, taking care not to raise the temperature above 122° Fahr. Then add from 2 to 5 drops of syrup, made with 5 parts sugar to 4 of water, and shake the mixture. If the liquid contain bile, a violet coloration is observed. Acetic acid, and those substances which are converted into sugar by sulphuric acid, may be substituted for sugar.

4399. To Detect Sulphur in Coal-Gas

4399.    To Detect Sulphur in Coal-Gas. The presence of sulphur in coal-gas can be proved in the following simple manner: Let a platinum basin be filled with a pint of water, and the basin be heated over a spirit lamp until all the liquid has evaporated; the basin will be found to be coated on the outside, where it has been struck by the flame, with a dirty, greasy looking substance, which, on being washed off with pure distilled water, and tested, proves to be sulphuric acid. The glass chimneys used with Argand gas-burners soon become coated over internally with a white substance, which, on being washed off with distilled water, will be found to be, on testing, sulphate of ammonia. The glass panes of a room wherein gas is burned for a few evenings consecutively, will, when rubbed with the fingers of a clean hand, impart to it a substance which, on the hand being rinsed in distilled water, will yield a precipi tate of sulphate, of baryta with chloride of.

barium, and a brick-red precipitate with potassio-iodide of mercury.

4400. Test for Benzole

4400.    Test for Benzole. For distinguishing genuine benzole, or that made of coal tar, from that prepared from petroleum, Brandberg recommends us to place a small piece of pitch in a testing tube, and pour over it some of the substance to be examined. The genuine will immediately dissolve the pitch to a tar-like mass, while that derived from petroleum will scarcely be colored. (See Nos. 4320 (Benzine) and 4321.)

4401. To Detect Cotton in Linen

4401.     To Detect Cotton in Linen. Unravel a piece of the fabric, both warp and weft, and plunge it into a solution of aniline and fuchsine. This will dye the whole red. Take it out, wash it, and while moist dip into ammonia; the cotton threads will lose their color, while the linen will remain red. (See No 296, etc..)

4402. Hahnemann's Test for Lead in Wine

4402.    Hahnemann's Test for Lead in Wine. Take 1 ounce quick-lime, 11/2 ounces flowers of sulphur; heat in a covered crucible for 5 or 6 minutes; take 2 drachms of this compound (which is sulphuret of lime), 2 drachms tartaric acid; powder, mix, and shake in a stoppered bottle with a pint of water; let it settle, pour off the clear liquid, and add 11/2 ounces tartaric acid. The above test will throw down the least quantity of lead from wines, as a very sensible black precipitate.