Lessons in Qualitative Chemical Analysis (Paperback, UK ed.)

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: CHEMICAL MANIPULATI0NS. 1. MANAGEMENT OF HEAT. For the purposes of qualitative analysis heat is usually produced by gas lamps. Where coal-gas is not obtainable, alcohol lamps may be used. The Bunsen Burner (fig. 2.) consists of a small burner (A) enclosed in a tube (B), open on top (E), to which air is admitted by round openings near the bottom of the tube. By turning a perforated collar (e, whose holes correspond with those in the tube, which it surrounds, the admission of air may be regulated and shut off entirely. The supply of coal-gas is admitted by the lateral tube (D), which is connected with the gas fittings of the laboratory by a rubber tube, and is regulated by an ordinary stopcock. Exercises. Turn on the gas and, after allowing it some time to fill the tube, light it at the to] (E). Now turn the collar (e so that the holes of the inner tube are closed. A bright, luminous flame, rich in carbon, will result. A piece of porcelain held into it will become FIG. 2. covered with soot. Now turn the collar so as to open the holes. The flame changes its character at once. The non-luminous blue color of burning carbon monoxide replaces the incandescent carbon, which had rendered the flame luminous. No soot will now be deposited on the porcelain. With this non-luminous, but very hot modification of the flame most operations of the laboratory are performed. ' FIG. 3. The following parts of the flame are to be noted: (fig. 3.) A dark cone in the center, rising from the base, consisting of unburnt gas mixed with a considerable portion of air; the outer flame consists of burning carbon monoxide, in which different parts are distinguished: The zone of fusion near the upper end of the dark cone, in which the temperature attains its highest degree, half-...