248 SUMMARY OF C.URRENT RESEARCHES RELATING TO 



vapour. The mass solidifies at once, and is ready to cut in J to J hour. 

 After 10 hours the mass becomes brittle and cuts badly. 7. Cut on the 

 sliding microtome with an oblique knife wetted with 1 p.c. salt solution 

 in distilled water. Transfer the sections to a dish of this salt solution, 

 i n which they spread out. After an hour they become opaque white 

 and crumble, therefore fix on the slide by the method described above 

 before this happens. 8. Remove the lead-gum by soaking the slides, 

 with sections attached, in 5 p.c. acetic acid for 5-15 minutes and wash- 

 ing in running water. Stain and mount as desired. 



Hollande's CMorocarmiii Stain mg Method. — Place 5 c.cm. pure 

 hydrochloric acid in a porcelain dish. Add little by little 14 grm. 

 powdered carmin, stirring constantly to make a homogeneous doughy 

 mass. Allow to digest for 24 hours. Add 250 c.cm. distilled water,, 

 bring to the boil, and keep boiling for J hour. Filter ; make up to 

 180 c.cm. with distilled water, and then add enough 75 p.c. alcohol to 

 make a total volume of 200 c.cm. Stain sections or pieces in this solu- 

 tion for 2-24 hours. Rinse in distilled water or 30 p.c. alcohol. 

 Immerse in 3 p.c. iron-alum solution, in which the sections become 

 black and are then slowly decolorized. When differentiation is com- 

 plete, rinse in 1 p.c. pyridin and wash under the tap for 10-15 minutes. 

 Counterstain and mount as desired. 



METALLOGRAPHY, Etc. 



Differential Crystallization in a Cast Steel Runner. — F. B. Foley 

 {Tlte Iron Age, Dec. 18, 1919). The author discusses a remarkable 

 specimen (some 2 in. in diameter) in which the microstructure varies 

 from normal " ingot " structure, through " Widmannstiittian " and back 

 to " ingot " again. Photomicrographs taken from the outside towards 

 the centre of the runner are appended. 



The Effect of Initial Temperature upon the Physical Properties 

 of Steel. — J. H. Andrew, J. E. Rippon, C. P. Milijer and A. Wragg 

 (Iron and Steel Institute Meeting, May, 1920). In this research the 

 effect of variation in initial temperature upon the position of the resulting 

 transformation points in certain Ni, Cr and Ni-Cr steels has been deter- 

 mined. 



The Structure of some Chromium Steels. — J. II. G. Moxypexny 

 (Iron and Steel Institute Meeting, May, 1920). It appears that the 

 properties of austenitic chromium steels are of great theoretical interest, 

 since they show that martensite is the first stage in the decomposition 

 of austenite. 



Note on the Structural Constitution, Hardening and Tempering 

 of High-Speed Steel containing Chromium and Tungsten. — K. Honda 

 and T. Murakami (Iron and Steel Institute Meeting, May, 1920). The 

 tempering of high-speed steel takes place in two steps, at approximately 

 400" 0. and above 700° C. 



