METALLURGY. 





ID reduce' tlir diameter and increase the 

 length of the cups until the flat disks of steel 

 ha\r assumed the form of tubes of the required 

 lengths, with an end closed, to bo cut off after 

 I lie final drawing operation has been performed. 

 The tubes are produced of si/es from 1} inch to 

 one sixteenth of an inch in diameter, are parallel 

 inside and outside, and are concentric. 



The following process for welding steel is 

 recommended in (iermany: Heat in an iron 

 vessel 04 parts of borax, 20 parts of sal-ammoniac. 

 10 parts of ferrocyanide of potassium, and 5 

 parts of colophony, all pulverulent, together with 

 s<>me waierand a spoonful of brandy. Stir well ; 

 let cool in the vessel, and then stamp to a 

 powder. The steel pieces to be welded are 

 Drought to a bright-red heat at the weld points, 

 and the process is then conducted in the usual 

 way with the help of the powder. 



The Coffin process for annealing steel, in use 

 by the Cambria Iron Company, it is claimed, 

 produces the important effect of materially 

 raising the elastic limit of the metal without 

 decreasing its ductility or ultimate strength. 



In his method for tempering steel by elec- 

 tricity, Capt. Lagrange, of the Belgian army, 

 uses the piece of metal as the negative electrode. 

 The temperature of the surface rises very high ; 

 the passage of the current is interrupted. By 

 this method, the inventor claims, particular parts 

 of a specimen may be tempered. 



A French manufactory, the Acieres de Saint- 

 Denis, is offering tools and mechanical pieces 

 generally manufactured according to a method 

 and with machinery permitting the supply in 

 ingot steel (acier fondu) of articles which hitherto 

 have been made of steeled iron or cemented cast 

 iron. With ingot cast steel (acier fondu conle) 

 having for base a central substance, finished iron 

 only, to the exclusion of crude iron or steel, the 

 Acieres obtain an ingot steel the fluidity of which 

 permits the manufacture by casting in pieces or 

 tools of a weight inferior to 15 grammes. This 

 steel, owing to its homogeneity, has a maximum 

 density. It can be tempered, like any other 

 ingot steel. 



Gold and Silver. In assays of gold bullion, 

 T. K. Rose observes, the amount of copper or sil- 

 ver contained in the assay piece very considera- 

 bly influences the " surcharge " or difference in 

 weight between the gold originally present in the 

 assay piece and the result finally obtained. The 

 presence of antimony, zinc, tellurium, iron, or 

 nickel reduces the surcharge by quantities which 

 the author has determined. It therefore follows 

 that to insure accuracy check assays must be 

 made on alloys of the same composition as those 

 under examination. Variations in the surcharge 

 are also caused by changes in temperature of the 

 muffle furnace used in cupellation. 



The peculiar feature of the cyanide-gold ex- 

 traction process of Mr. W. Ilannayisthe stirring 

 tip the ore in an electrolytic cell with a carbon 

 anode and necessary cathode. 



In the method devised by William Beitel for 

 treating the slimes formed under the action of 

 the cyanide-gold process, a mass of the slimes is 

 mixed with 50 per cent, of its weight of the dou- 

 ble cyanide of manganese and potassium, mixed 

 with ordinary cyanide solution. While in a state 

 of suspension the mixture is charged into a filter 

 VOL. xxxni. A 31 



pro- under pressure, water is forced through, and 

 the ^old-cyanide solutions are thoroughly wa-h-d 

 out. The forcing of water is continued until the 

 escaping fluid does not show an alkaline reaction. 



The gold ore concentrator of F. W. (Jrey and 

 W. Marsh is provided with an outlet which is ad- 

 justable relatively to the inlet, and also with 

 means whereby the capacity or area through 

 which the ore passes can be varied. The concen- 

 t rat or may consist of a vessel preferably of an in- 

 serted conical or pyramidal form, within which 

 is placed a box of corresponding form, so as to 

 leave a space between the latter and the interior 

 of the outer vessel. This space is made adjust- 

 able to suit various classes of ores being treated. 

 The ore, mixed with the necessary amount of 

 water, is introduced at one end of the space, say 

 the bottom, and passes up toward the outlet. 



Discussing the limits of accuracy of the analy- 

 sis of gold bullion, T. K. Rose observes that if 

 attention be paid to the certain causes of error 

 which he points out. the gold in bullion of a high 

 degree of purity can be determined within a range 

 of 0'02 per 1,000, the limits of accuracy having 

 been previously considered to be 0' 10 per 1,000. 

 This extreme degree of accuracy is possible only 

 if the check gold be pure. The losses of gold in 

 bullion assaying are due to absorption by the 

 cupel, volatilization in the muffle, and dissolu- 

 tion in the parting acid. The losses found in a 

 number of assays, the results of which are given, 

 range from 0-44 to 0-64 parts per 1,000. Con- 

 cerning the loss by volatilization, it was found 

 that an increase takes place when the tempera- 

 ture is high, pure gold losing four times as much 

 at 1245 as at 1090 : that a large amount of 

 gold is volatilized in an atmosphere mainly con- 

 sisting of carbonic oxide, while a small amount 

 is lost in coal gas ; that a comparatively small 

 amount of gold is carried away by the more vola- 

 tile metals, copper appearing to exert an excep- 

 tional action ; metals which are easily volatilized 

 do not appear to be completely driven off by the 

 highest temperatures attained in the experiments: 

 and that a large proportion of gold is lost in the 

 case of alloys that form flat buttons on the cupel, 

 and conversely, a small proportion is lost from 

 spherical buttons, although the surface actually 

 exposed is greater in the latter case than in the 

 former. A current of air or gas passing over the 

 buttons does not seem to increase the loss, pro- 

 vided the surface of the molten metal remains at 

 rest. These results point to the conclusion that 

 the conditions which lower the surface tension of 

 the gold button simultaneously raise the vapor 

 pressure of the gold. Prof. Roberts- Austen ob- 

 served, in the discussion of the paper in the 

 Chemical Society of London, that he and his two 

 colleagues in the assay office of the British mint 

 had made in the past year 30,000 assajs of gold, 

 and they had every reason to believe that their 

 average accuracy was i^tron part. 



Rich argentiferous ores containing blende are 

 treated by J. David in such a manner as to in- 

 crease the yield of silver and promote the recov- 

 ery of the zinc while lessening the cost of treat- 

 ment. The ore is reduced to a fine powder and 

 mixed with a boiling solution of chloride of iron 

 (a waste product from tin-plate works), to which 

 re added hydrochloric acid and oxidizing agents. 

 The sulphide of zinc is then decomposed, the zinc 



