Early in the year 1915 it became evident that a large quantity of copper and srlter would be required, by the mills of the Untted States, for use in the manufacture of ammunition for the warring nations of Europe, and the price of these metals rapidly advanced until, in 1916. copper was quoted at 34 cents per pound and spelt.er at from 18 to 30 cents according to the quality of the metal and the time of delivery, the highest price being paid for immediate re quirements. Brass rolling-mills running day and night were unable to supply the denaand for brass; existing mills increased their facili ties; new mills were started; old and disused mills were put in operation; wages were ad vanced; labor became scarce and serious strikes occurred, for the first time in the history of the business. Brass rolling became very profitable and the shares of corporations engaged in that business doubled in value within a year.
In brass rolling-rnills the copper is received in the form of ingots and the spelter in the form of plates which are broken when required for use. The copper is melted in crucibles and the spelter is then added in the proportion required, the standard mixture being about two parts copper to one part spelter. This raixture and those containing a higher percentage of copper are rolled and worked when cold. The cornbination of 60 pounds of copper with 40 pounds of spelter is known as yellow metal and is usually rolled while hot into sheets and rods. The melted brass is poured from the crucibles into sectional molds from wlaich when cooled it is taken in the form of slabs, approximately of the width required for the finished product. These slabs are then reduced and elongated by passing through rolls of chilled iron. Frequent annealing is required between the successive passes and the oxide forming upon the surface of the metal in the process of annealing is removed by baths of dilute sulphuric acid.
Brass rods are drawn from round bars by successive passes through dies on draw-benches. Brass wire is produced by drawing the metal through a succession of dies by means of re volving drums on which the wire is coiled. Seamless brass and copper tubes are usually cast in hollow form round a core asid finished on draw-benches by drawing through dies over mandrels. Another process consists of piercing a bar of metal by a steel mandrel over which the metal is drawn by the action of conical rolls revolving at a high speed; the shell thus formed is then drawn into a tube in the ordi nary manner. Brass rods and tubes of intricate shape are formed by a process of extrusion by means of which the metal, after being heated to a temperature of about 1,000° F., is placed in a cylindrical container at one end of which is the die and, upon pressure being applied at the opposite end by means of a hydraulic ran. the metal, which is in plastic condition, is forced through the die, issuing therefrom as rods or tubes of the required section and of a length governed by the quantity of metal placed in the container. In this way metallic sections are produced in complex designs with re-entering angles which it would be Impossible to roll or draw. An admixture of brass and nickel pro duces the white metal known as German silver, used in the manufacture of spoons, forks and other articles which, when plated, have the ap pearance of silverware. Sheet copper and copper rods are rolled at a red heat from cast plates and bars and, when a fine surface is required, they are finished by cold rolling or drawing. In the rolling of brass and copper the accumulation of clean scrap metal is re melted and used.