520 SUMMARY OF CURRENT RESEARCHES. 



Surface-flow.* — Cast-iron wearing surfaces, such as the bore surfaces 

 of steam and internal -combustion engine cylinders, give the least 

 t rouble and the most endurance after they have become " glazed " by 

 use. J. E. Hurst states that such hard glazed surfaces are fine examples 

 of surface-flow, and gives photomicrographs illustrating their formation. 

 The thickness of the flowed layer may be 0*005-0 -01 mm. The hard 

 layer is attacked only slowly by nitric acid. The cast-irons studied 

 consisted mainly of ferrite and pearlite, with hard phosphide eutectic 

 and graphite plates. Wear causes the phosphide eutectic to stand in 

 relief. The hard flowed surface layer formed appears to consist of the 

 amorphous phase of ferrite, together with some amorphous product of 

 the hard phosphide eutectic, and possibly other constituents. 



Gold-cadmium Alloys. f — P.J. Saldau finds that gold and cadmium 

 form two compounds, AuCd and AuCd 3 , giving solid solutions with 

 their components within certain limits. Gold and AuCd, and cadmium 

 and AuCd 3 , form solid solutions containing, respectively, up to 

 35 atomic p.c. of cadmium and 2 atomic p.c. of gold. 



Preparation of Metal Specimens.:): — The Wysqr combined grinding 

 and polishing machine, recently placed on the market by Eimer and 

 Amend, New York, is described. The carborundum grinding wheels 

 are carried on the horizontal shaft, the roughing wheel being on one end 

 and the medium and finishing wheels on the other end. The polishing 

 disks are of brass with cloth coverings, and are easily replaceable on the 

 head of the vertical spindle, which is driven by contact with a friction 

 wheel on the horizontal shaft. The speed of rotation of the polishing 

 disks may be varied by shifting the friction wheel on the shaft. After 

 grinding, the specimen is polished in turn on (1) canvas with emery 

 flour, (2) broadcloth with tripoli, (3) broadcloth with rouge. The polish- 

 ing powders are mixed with water to the consistency of flowing paste ; 

 glass bulb-holders are used for applying the pastes to the disks. The 

 machine appears to be compact and convenient. 



* Engineering, c. (1915) pp. 130-1 (5 figs.). 



t Journ. Russ. Phys. Chem. Soc, xlvi. (1914) pp. 994-1027, through Journ. 

 Chem. Soc, cviii. (1915) p. 353. 



% Met. and Chem. Eng., xiii. (1915) pp. 400-1 (2 figs.). 



