352 SUMMARY OF CURRENT RESEARCHES. 



varied from 0*046 to 0'83 pc, the carbon-content remaining constant 

 at 2*9 pc. The alloys were examined as cast, and after annealing at 

 900° C. for two and a half days and cooling slowly. Stead's cnpric 

 reagent deposited copper readily on the low-phosphorus specimens, and 

 less readily as the phosphorus-content was higher, but did not give com- 

 pletely satisfactory indications of the distribution of the phosphorus 

 within each specimen. A ring surrounding each nodule of carbon in the 

 -annealed specimens remained free from copper, but this could not be due 

 to local high phosphorus. The author suggests that during the cooling 

 of steel through the critical ranges the phosphorus may become con- 

 centrated, together with the carbon, in the pearlite areas. 



Metallography.— H. Le Chatelier gives an account of the origin and 

 development of the science of microscopic metallography. Successive 

 improvements in the technique of polishing, etching, and photomicro- 

 graphy are described. The application of metallography to the study o 

 alloys is illustrated by numerous photomicrographs. 



* Rev. M^tallurgie, xii. (1915) pp. 1-36 (52 figs.). 



