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I N D UXTRIAL A N D ENGINEERING CHEMISTRY ELECTRIC MELTINGOF ALLOYS
The most important change in practice in the preparation of alloys which has occurred in the last few years is electric melting. This evolution, or more properly revolution, in casting practice is now in progress. The most popular and probably most efficient melting device is the induction furnace. I n several of the more important establishments the greater part of the melting is being done in induction furnaces. Some of the mills and foundries have apparently made successful application of arc type furnaces. The most recent developments seem to indicate that each type has a distinct field in which it will find its most economic and efficient application. Exaggerated claims have been made as to the superior quality of electrically melted brass. The truth of the matter is that electric melting has proved more economical than melting with coal or coke. The electric furnace removes any possibility of the absorption of gases from fuel combustion by the metal and allows a somewhat closer heat regulation. It is much easier for the workmen to operate than the crucible furnace. Electric melting reduces the zinc losses incident to crucible melting, but it has by no means overcome all the troubles that may occur in casting alloys, and the same careful practice and supervision must still be exercised to achieve success. CORROSION The question of the corrosion of metals and alloys is one of the most important which affect their industrial application and use. The National Research Council is now actively organizing and coordinating the research facilities of the country for comprehensive work in this direction. Much effort has been put into the study of corrosion, with comparatively little definite or practical result. There is still considerable difference of opinion as to the choice to be made among metals or alloys for certain commercial purposes, and failures which now and then occur result in bringing the misapplied material into disrepute. Modern conditions have intensified the corrosive action to which metals are exposed in everyday service through increased pollution of the atmosphere and water supplies. Industrial uses are generally becoming more intense, and the proper choice of metals to meet the conditions of service is essential. This means that a more thorough understanding of corrosive action and its effect on various materials is necessary. The persistence and insistence of Alfred D. Flinn in demanding that the reason for the spontaneous failure of certain alloys used by the New York Board of Water Supply be found and understood is still giving results. Means have been found for preventing the spontaneous cracking of rods and bars when exposed to corrosion, and there is no further danger of the failure of properly finished wrought bronzes and brasses from internal stresses when such material is exposed to corrosive action. OTHERLINESOF PROGRESS The cracking of tubes, both for condensers and water-supply pipes, has been eliminated, so there is now no danger from split piping in the water supply of buildings, if brass is used. Considerable progress has been made with the study of the effect of fatigue on steels or ferrous alloys, but practically nothing has been done in the nonferrous field. The subject is important and researches are promised in this direction. The use of the white alloys of copper, nickel, and zinc is becoming more prominent, particularly in the field occupied by plated material. Such alloys &re resistant to corrosion, durable and pleasing in appearance, and at the same time have
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good physical properties. This type of alloy has been known for years under the general name of ‘(German silver.” It has always been an attractive field for “inventors” who, through want of knowledge of the nickel alloy, have made fanciful claims as to their remarkable properties. Just a t present there seems t o be a new epidemic of “invention” of “Super German Silver” with most wonderful properties, some of which are said to be obtained through the use of secret fluxes which leave no trace behind. The growing use of electrical equipment, both in industry and for the household, has stimulated the use of copper in all forms and also that of many of the copper alloys. Cadmium is now one of the commercial metals. It has, when used in small quantities, the effect of increasing the strength of copper without seriously decreasing its conductivity. Cadmium or cadmium and tin together are being used for producing stronger conductor and trolley wires. Magnesium and magnesium alloys are receiving considerable attentionj but have not yet become industrially important. The progress being made with aluminium and the light alloys has so recently been outlined by Gillett2that there is nothing further to be said at this time. I n general, 1922 has brought a revival in the wrought nonferrous industry, with continued study of the application of the metals and alloys to engineering and domestic needs. The educational campaign being carried out by several of the important factors in the production of metals and alloys will undoubtedly result in a more intelligent use of these products and an increased consumption. There is still much to be gained by such researches as have been mentioned, and more benefit will be derived from the systematic study of the properties of the materials already familiar than is likely to result in attempts to find new combinations. a
THISJOURNAL, 14 (1922), 865.
A Simple Check Valve’ By J. F. Brewster LOUISIANA SUQAR EXPERIMENT STATION, NEWORLEANS,
LA.
The accompanying sketch is intended to represent a check valve made from materials to be found in the chemical laboratory. It was devised for use with the water vacuum pump to prevent flooding of apparatus when a “suck back” occurs in case of variation in water pressure. A solid rubber d stopper, shown at a L in %e sketch, is cut about three-quarters through at the small end so that a thin flap of rubber, b, is left to serve as the valve leaf. The stopper is then bored, leaving the flap intact, to receive the short length of glass tubing, e, which should be pushed to within a few millimeters of the valve seat. A short length of glass tubing, of such diameter as to allow free play of the leaf and at the same time fit the stoppers tightly, is closed a t one end by the valve stopper and at the other by the one-hole stopper c, carrying glass tubing f. By means of rubber tubing, f is connected with the pump, and e with the system to be evacuated. Any convenient sizes of stoppers and tubing may be used. 1 Exhibited before the Division of Sugar Chemistry at the 64th Meeting of the American Chemical Society, Pittsburgh, Pa., September 4 t o 8. 1922.
