1870.] Metallurgy. 423 



liberated hydrochloric acid. The process is continued until all the 

 copper is thrown down, which point is at once observed by sulphu- 

 retted hydrogen being evolved, when the process is stopped ; for if 

 continued, the ammonia would now neutralize the free acid, and the 

 iron would then be precipitated. The sulphide of copper thus ob- 

 tained is very nearly pure ; it is washed and dried, and smelted into 

 copper by any of the usual methods employed. 



A new process of calcining tin and other ores has been adopted 

 by Messrs. Oxland, F.C.S., and John Hocking. The ores are 

 introduced into a revolving iron cylinder, 4 feet in diameter and 

 30 feet long, lined with fire bricks, and supported at an inclination 

 of about | inch per foot on three pairs of rollers, on which it is kept 

 constantly revolving at a slow rate. The fire passes from the fire- 

 place over a chamber into and through the tube. The ore having 

 been first dried on iron plates in suitable flues, at the back of the 

 calciner, is admitted in a steady stream into the higher end of the 

 cylinder, and the slow revolving motion imparted to it causes the 

 advance of the ore by its own gravitation, and it is discharged in a 

 continuous stream into a chamber between the fire-place and the 

 front of the tube. Great economy of fuel is said to be effected by 

 this furnace. The heat from the fuel has to traverse more than 

 double the distance over which it passes in Brunton's calciner before 

 it escapes into the flues, and the tube presents nearly double the 

 amount of heating surface. None of the working parts are exposed 

 to the action of the fire. In working it is found to be economical 

 both as regards fuel and labour. 



Several patents have been taken out of late relating to the 

 manufacture of iron and steel. Mr. Cowper, of Westminster, patents 

 improvements in treating cast iron for the production of wrought 

 iron and steel therefrom. By this process the purification of the 

 cast iron is accomplished by a jet of superheated steam applied to 

 a stream of the liquid iron as it flows from the blast furnace, so as 

 to divide it up into small particles, and act upon them ; the iron is 

 received into a hot box, and transferred to a calcining furnace, in 

 which it is kept hot whilst still exposed to an atmosphere of hot 

 steam ; such purified iron is mixed either hot or cold with liquid 

 cast iron, and afterwards used as cast iron, or made into steel or 

 wrought iron. 



In the manufacture of steel Mr. Julius Baur, of New York, 

 patents a process of alloying or combining metallic chromium with 

 metallic iron, so that chromium in a metallic state shall be present 

 in the finished product, which is said to impart valuable properties to 

 it. This process is distinguishable from that secured by Mr. Kobert 

 Mushett for mixing oxide of chromium in the manufacture of steel. 



Letters patent have also been granted to Mr. J. M. Stanley, of 

 Sheffield, for improved modes of utilizing the heat given off during 



