PROCEEDINGS OF THE SOCIETY. 271 



phous, on heating to and quenching from a higher temperature, a 

 crystalline structure was strongly developed, and had the same charac- 

 teristics as martensite in steels containing less carbon. 



Troostite and austenite, although not thoroughly understood, had 

 been recognised as true micro-constituents. 



Sorbite, like troostite, required more study. It was neither troostite 

 nor pearlite, and Osmond had described it tentatively as unsegregated 

 pearhte. As much discussion had taken place during the last few years 

 with regard to the nature of the micro-constituents — sorbite, troostite, 

 and austenite — a committee had been formed to work under Dr. Glaze- 

 brook, of the National Physical Laboratory, to endeavour to ascertain 

 their true nature. 



The work of Professor Arnold was illustrated by slides made from 

 accurate drawings of the structures of cement steels and steels containing 

 sulphur. 



The lecturer expressed great appreciation for Arnold's drawings, and 

 pointed out that in many cases they were preferable to photographs, but 

 that generally photographs were better when properly taken. 



The special features of Professor H. Le Chatelier's work were illus- 

 trated by photomicrographs of cast irons and steels, some of the struc- 

 tures of which had been developed by the action of potash and lead 

 oxide, which darkened the cementite but left the other constituents white. 



The mid-ribs of cementite in the dark barbs of martensite were in 

 this way clearly shown. 



The effect of strain and continued reversals of stress on iron was 

 illustrated by photomicrographs prepared by Professor J. A. Ewing, 

 Mr. Walter Rosenhain, and Mr. Humphrey. 



The surface-flow of metals was illustrated by the elaborate work of 

 Mr. G. T. Beilby. 



The work of Mr. W. H. Merrett, of the Royal College of Science, 

 was represented by photographs of granular pearlite, magnified 1600 

 diameters, which showed that the carbide of iron, or cementite, existed 

 in globular or roughly-shaped globular particles completely separated 

 from each other. 



The micro-structures of steels produced by electrical processes were 

 given by slides provided by Mr. F. W. Harbord, and shown to be 

 identical with the micro-structures of steels made by the ordinary 

 processes. 



The structure of bronzes was very beautifully illustrated with slides 

 provided by Messrs. C. T. Heycock and F. H. Neville, Cambridge. The 

 lecturer, in describing the work of those gentlemen, remarked that the 

 research upon Copper and Tin Alloys, presented to the Royal Society, 

 was of the highest merit, and a type of work such as students, who 

 wished to study metallic alloys, should take as an example. 



At the conclusion of the lecturer's remarks — there being no time for 

 discussion— the Chairman said he felt sure that all who were present 

 would join in a very hearty vote of thanks to Mr. Stead for the ex- 

 hibition given to them that evening of a very remarkable and highly 

 interesting series of slides illustrating a subject of great scientific and 

 economic interest. 



The thanks of the Meeting were then unanimously voted to Mr. 

 Stead for his very interesting communication. 



Mr. Stead, in responding, said he thought he himself ought to thank 



