Handbook for the Bio-Chemical Laboratory (Paperback)

Purchase of this book includes free trial access to www.million-books.com where you can read more than a million books for free. This is an OCR edition with typos. Excerpt from book: 75 Jakacli, Knapp, LoweniJtal, Moore, Moliscli, Mulder, Nylan- der, Fenzoldt, Pavy, Roberts, Rubner, Soldani, Scliiff, Trom- mer, Wenders. Ghelin's Test (Bile Pigments).?If nitric acid containing some nitrous acid is carefully poured beneath a solution containing bile pigments, a series of colored layers are obtained at the juncture of the two liquids in the following order from above downwards: green, blue, violet, red, and reddish yellow. The green ring must never be absent, and also the reddish violet must be present at the same time, otherwise the reaction may be confused with that for lutein, which gives a blue or greenish ring. The nitric acid must not contain too much nitrous acid, for then the reaction takes place too rapidly and does not become typical. Alcohol must not be present, because it gives a play of colors with the acid. Gkiess's Eeagent (Nitrous Acid).?A solution of metadiam- ido-benzol (melting at 63 C.) gives an intense yellow coloration with dilute solutions containing nitrous acid which have been acidified with a few drops sulphuric acid. Grigg's Test (Proteids).?A solution of meta-phosphoric acid gives a precipitate with all proteids witk the exception of the peptones. Guanin. See Capranica. Gunning's Test (Acetone).?Add an alcoholic solution of iodine to the liquid to be tested and then ammonia. On standing a precipitate of iodoform and a black precipitate of iodide of nitrogen is formed, but this latter gradually disappears on standing, leaving the iodoform visible. Gunzbukg's Reagent (Hydrochloric Acid). ? Dissolve 2 grms. phloroglucin and 1 grm. vanillin in 100 c.c. alcohol. In testing for the presence of free Hn add an equal amount ofthe above reagent to the liquid to bo tested in a porcelain dish and evaporate the mixture on the...