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Alkaline polysulphides
222
CURRENT TOPICS.
[J. F. I.
C o p p e r - c a d m i u m W i r e . N. 1~'. ]3UD(;FN. (Electrician, April 3o, I 9 2 6 . ) - - T h e metal cadmium has acquired a new importance from the valuable properties of its alloys with copper, tin and zinc, but it is likely that its chief application in the future will be as a constituent to a small degree in drawn copper wire. Smith in I92I found that copper wire containing a little cadmium was scarcely reduced in electrical conductivity, while it possessed a high tensile strength and resistance to abrasion. The conductivity comes down less than I per cent. for each .1 per cent. of cadmium added to the copper. The tensile strength increases slowly with added cadmium until the latter amounts to .6 per cent. The addition of more cadmium causes a rapid increase in the tensile strength. Copper wire with I.t per cent. cadmium can be subjected to a temperature of 26o ° for thirty minutes and afterwards show scarcely any sign of s o f t e n i n g - - a marked contrast to the effect produced on pure copper by the same heat treatment. A copper-cadmium wire with 2o per cent. greater tensile strength than a wire of pure copper can be bent seven times to a right angle and back before it hreaks, whereas the wire of pure copper breaks after four such bends. In a torsion test the compound wire showed itself four times as good as the pure one. In a test of trolley wire under working conditions the loss in diameter during eight months was less than one-third as much for copper-cadmium wire as for copper wire. On account of its properties above given copper-cadmium wire has approved itself for technical uses in both hemispheres. G. F. S. Alkaline Polysulphides.DCARL Z. DRAVES and HER~,~AN V.
TARTAR, Of the University of Washington (Your. Am. Chem. Soe., 1926 , 48, i 5 2 7 - I 5 2 9 ) , have studied the reaction which occurs when metallic sodium or potassium is added to an excess of sulphur dissolved in boiling toluene in an atmosphere of hydrogen. The sulphides which form are insoluble in toluene. They were collected, and subjected to quantitative analysis. Sodium yielded its trisulphide, Na2S3, while potassium yielded its pentasulphide, K2S~. J. S. H. A N e w Steel for Small H o u s e s . (Popular Science Monthly, July, 1926, p. 5 5 . ) - - A light structural steel which can be used for small houses in much the same manner in which heavier beams are employed in skyscrapers has been perfected recently by a Pittsburgh manufacturer. The new steel, while light in weight, has greater proportional strength than any other steel so far produced. Hitherto lightweight steel was impossible because there was no known way of rolling it, but after many years the necessary rolling process has now been perfected. The new steel can be used for floors and roofs as well as for beams. R.
CURRENT TOPICS.
[J. F. I.
C o p p e r - c a d m i u m W i r e . N. 1~'. ]3UD(;FN. (Electrician, April 3o, I 9 2 6 . ) - - T h e metal cadmium has acquired a new importance from the valuable properties of its alloys with copper, tin and zinc, but it is likely that its chief application in the future will be as a constituent to a small degree in drawn copper wire. Smith in I92I found that copper wire containing a little cadmium was scarcely reduced in electrical conductivity, while it possessed a high tensile strength and resistance to abrasion. The conductivity comes down less than I per cent. for each .1 per cent. of cadmium added to the copper. The tensile strength increases slowly with added cadmium until the latter amounts to .6 per cent. The addition of more cadmium causes a rapid increase in the tensile strength. Copper wire with I.t per cent. cadmium can be subjected to a temperature of 26o ° for thirty minutes and afterwards show scarcely any sign of s o f t e n i n g - - a marked contrast to the effect produced on pure copper by the same heat treatment. A copper-cadmium wire with 2o per cent. greater tensile strength than a wire of pure copper can be bent seven times to a right angle and back before it hreaks, whereas the wire of pure copper breaks after four such bends. In a torsion test the compound wire showed itself four times as good as the pure one. In a test of trolley wire under working conditions the loss in diameter during eight months was less than one-third as much for copper-cadmium wire as for copper wire. On account of its properties above given copper-cadmium wire has approved itself for technical uses in both hemispheres. G. F. S. Alkaline Polysulphides.DCARL Z. DRAVES and HER~,~AN V.
TARTAR, Of the University of Washington (Your. Am. Chem. Soe., 1926 , 48, i 5 2 7 - I 5 2 9 ) , have studied the reaction which occurs when metallic sodium or potassium is added to an excess of sulphur dissolved in boiling toluene in an atmosphere of hydrogen. The sulphides which form are insoluble in toluene. They were collected, and subjected to quantitative analysis. Sodium yielded its trisulphide, Na2S3, while potassium yielded its pentasulphide, K2S~. J. S. H. A N e w Steel for Small H o u s e s . (Popular Science Monthly, July, 1926, p. 5 5 . ) - - A light structural steel which can be used for small houses in much the same manner in which heavier beams are employed in skyscrapers has been perfected recently by a Pittsburgh manufacturer. The new steel, while light in weight, has greater proportional strength than any other steel so far produced. Hitherto lightweight steel was impossible because there was no known way of rolling it, but after many years the necessary rolling process has now been perfected. The new steel can be used for floors and roofs as well as for beams. R.