198 



NATURE 



[October 6, 192 1 



of the zinc-copper alloys. Experiments were con- 

 ducted with alloys made from pure metals and cast in 

 sand- and chill-moulds respectively. There is a con- 

 traction in volume due to alloying with mixtures con- 

 taining more than 25 per cent, of copper, and the 

 density of the sand-cast or slowly cooled alloys is 

 generally less than that of the chill castings ; at 

 points where the liquidus and solidus coincide on the 

 constitutional diagram, chill castings and sand cast- 

 ings give the same values. The expansion recorded 

 by Turner and Murray with alloys containing less 

 than 30 per cent, of copper is confirmed, and is shown 

 to be connected with a new form of porositv different 

 from ordinary unsoundness. — Dr. F. Johnson : Experi- 

 ments in the worl^ing and annealing of copper. 

 Part I : Critical ranges of deformation probablv result 

 from stages of abnormal plasticity during rolling of 

 the metal. It is suggested that during these stages 

 the metal actually loses some of the increase of hard- 

 ness conferred in earlier "passes." A decrease of 

 volume up to 8.^ per cent, occurs; the increase of 

 volume which then sets in may correspond to the 

 inception of permanent disability which cannot be 

 eradicated by annealing. Part 2 :' At 200° C. for one 

 hour softening occurs in all strips rolled beyond 40 per 

 cent, reduction. Test-pieces from the axes of the 

 strips undergo softening to a greater extent than edge- 

 specimens from the same series when annealed under 

 the same conditions, thus indicating a greater intensity 

 of strain at the centre than at the edges. High- 

 temperature annealing at 750° C. shows that at 87 per 

 cent, reduction a rapid decrease in strength sets in. 

 Part 3 : Low-temperature annealing of cold-drawn 

 copper rods of varying compositions. "Tough-pitch " 

 arsenical rods retain their strength practically un- 

 impaired up to 300° C, whereas "tough-pitch " elec- 

 trolytic copper undergoes considerable loss of strength. 

 The presence of silver in arsenical rods raises slightly 

 the annealing temperature. The substitution of iron 

 for oxygen in arsenical copper retards the rate of 

 softening.— W. E. Alkins and W. Cartwright : The 

 effect of progressive cold-drawing upon some of the 

 physical properties of low-tin bronze. The tin content 

 varied from about 07 to about i-n per cent, in the 

 three samples of bronze studied. The most important 

 and rapid changes in properties occur after a reduc- 

 tion of 85 per cent, of the original area, i.e. over the 

 range where practical difficulties are met with during 

 drawing. The extent of the variation in tensile 

 strength, specific volume, and scleroscooe hardness is 

 very similar to that previously found in the case of 

 copper. 



September 22.~R. Genders : The extrusion defect. 

 Experiments have been carried out with the object of 

 devising a method of extrusion which would avoid the 

 formation of the defect known as "piping," which 

 is commonly found in some centrally extruded rod made 

 from brass and other non-ferrous alloys by the usual 

 hot-extrusion process. The defect is tubular in the 

 interior of the rod, and generally exists in the last 

 portion extruded. When a defective rod is broken 

 across, the core frequently breaks at a different point 

 from the outer ring. The defect consists of foreign 

 matter, oxide and dezincified brass, which constituted 

 the_ skin of the original billet. Billets extruded to 

 various stages and sectioned axiallv show the presence 

 of the defect in the shape of a funnel. The defect 

 can be largely overcome by the use of a ram smaller 

 in diameter than the billet, which causes the outer 

 laver of the billet to remain in the receiver as a thin 

 cylinder, but the method would probably be too waste- 

 ful on a large scale. By inverting the process so that 

 the die is pushed through the billet the mode of flow 



NO. 2710, VOL. 108] 



is altered. There is no relative movement between the 

 billet and receiver, and flow is confined to the region 

 of the die. The power required is less than with the 

 method at present in use. ITie method is in use in 

 many places for the production of tubes and rod from 

 soft metals. — F. S. Tritton : The use of the scleroscope : 

 on light specimens of metals. Errors were detected 

 when using the ordinary methods of support, and to- 

 reduce them pitch and glucose were selected. The 

 use of pitch requires a special clamp, a new type of i 

 which is described. A solution of glucose considerably \ 

 stiffer than treacle gave good results, the specimens \ 

 being attached by means of the glucose to a hard 

 steel base. The hardness of specimens having both 

 flat and curved surfaces can be tested provided that a 

 recessed support be made to fit the specimens. — D. H . 

 Ingall : The relation between mechanical properties 

 and microstructure in pure rolled zinc. The material 

 as rolled, and also when annealed, at 100° and 

 150° C, is ductile "with" and brittle "across" the 

 direction of rolling, with reduction from 77 to about 

 87 per cent. ; it is ductile in all directions v^dth q6 per 

 cent. reduction by rolling, where the strength has 

 risen from about 6 to about 13 tons per sq. in. An : 

 equi-axed structure exists in all cases. Annealing for 

 thirty minutes at 200° C. renders the material com- 

 pletely brittle and weak, due to a crystallisation. — Dr. D. 

 Hanson and Marie L. V. Gayler : The constitution and ' 

 age-hardening of the alloys of aluminium with mag- 

 nesium and silicon. The ternary system aluminium, 

 magnesium, and silicon, containing up to 35 per cent, 

 of magnesium and 11 per cent, of silicon, has been 

 investigated. Thermal curves and microscopic 

 examination prove that magnesium and silicon form ; 

 a chemical compound having the formula Mg^Si, 

 which with aluminium forms a eutectiferous binary 

 system, having an eutectic containing 13 per cent, of 

 Mg.Si, and melting at 590° C. The aluminium- 

 Mg.Si-silicon system possesses a ternary eutectic that 

 melts at 550° C. ; the ternary eutectic of the 

 aluminium-Mg,Si-magnesium system melts at 450° C^ 

 The solubility of MgoSi in solid aluminium is i-6 per 

 :ent. of Mg.Si at 580° C. and about 05 per cent, at 

 30° C. Excess of silicon has little eftect, but mag- 

 nesium reduces the solubility at high temperatures. 

 The difference in the solubility of MgjSi at high and 

 low temperatures is the cause of the age-hardening' 

 property of these alloys, which in a series of alloys \ 

 containing increasing amounts -of MgjSi rises pro-*" 

 gressively until the limit of the solubility of MgiSij 

 in aluminium at the quenching temperature is reached, 

 bevond which the total increase in hardness remains] 

 constant. The increase in hardness is roughly pro- 

 portional to the amount of Mg^Si retained in solution^ 

 by quenching. — F. Adcock : The electrolytic etchings' 

 of metals. A solution of citric acid as an electrolyte' 

 in the etching bath gave good results with cupro- 

 nickel (80 : 20), silver, nickel-silver, and some other ' 

 metals. Certain specimens of silver showed on etch- 

 ing a cell-structure or network which was smaller 

 than, and in some cases independent of, the existing 

 crystal grains. Another electrolyte made by dissolv- 

 ing molybdic acid in excess of ammonia solution gave 

 similar results, and revealed a subsidiary cell-formation 

 or network in the ^-regions of a ^+7 brass containing 

 6 per cent, of aluminium. By using hydrofluoric 

 acid, chromic acid, and bromine water, both the cores 

 and the crystal-grain boundaries of cast cupro-nickel 

 were disclosed simultaneously. — S. Beckinsale : The 

 magnesium alloy "electron." Samples of the new 

 high magnesium alloy "electron * contained about 

 95 per cent, of magnesium, 45 per cent, of zinc, and 

 05 per cent, of copper. The alloys machined well, 



