110 PROCEEDINGS OF THE SOCIETY. 



Mr. F. TwYMAN read a paper on " The Annealing of Glass." 

 Badly annealed glass meant the presence of internal stress. The 

 annealing range of temperature is the limited intermediate one during 

 which stresses take some little time to die out, and an accurate know- 

 ledge of the mechanical properties of glass in this region is necessary. 



The remaining papers and communications dealt with various appli- 

 cations of the microscope. 



Dr. J. W. Evans, F.R.S., spoke on " The Requirements of the Petro- 

 logical Microscope." 



Besides having the functions of an ordinary microscope, the petro- 

 logical microscope had to identify crystals by the action of light upon 

 them. The provisions specially designed for this purpose were described. 



Mr. A. Chaston Chapman, F.I.C, spoke on "The Application of 

 the Microscope to the Selection and Control of Yeast employed for 

 Brewing Purposes." 



It is possible to detect the contamination of the pitching yeast of 

 the brewery with bacteria and undesirable yeast species and to take the 

 necessary steps to purify it. 



Lantern slides were shown illustrating this fact. 



Dr. R. S. Willows, M.A., presented a paper describing "The 

 Microscopic Outfit of a Textile Research Laboratory." 



It is pointed out that the design of a microscopic outfit for research 

 on textiles has not yet received due attention. Attention is particularly 

 directed to the importance of considering more fully the mechanical design 

 of the photographic apparatus, so as to lessen the effects of vibration ; 

 the provision of a simple method of changing from transmitted to 

 vertical illumination and of a reflecting device to enable a vertical 

 microscope to be used with a horizontal camera, in cases where the 

 effect of solutions is being followed. 



The next group of papers dealt with the use of the microscope in 

 metallography. 



A paper by Sir Robert Hadfield, Bart., on " The Great Work of 

 Sorby of Sheffield," introduced the subject. 



The late Dr. Sorby, the founder of the science of metallography, 

 first worked as a geologist on transparent rock sections, but he sub- 

 sequently realized the immense advantage of the application of the 

 microscope to the structure of metals, his first paper on this subject 

 being read in 1864. His earlier work was for some years neglected, 

 but in view of the immense strides which were subsequently made in 

 the science of metallurgy, the microscope, in the hands of such men as 

 Martens, Osmond and le Chatelier, became one of the most powerful 

 instruments of research. To Sorby, however, belongs the credit of 

 having first evolved the microscope method ; it was his discovery of 

 the means whereby the structure of a metal can be laid bare that gives 

 him the ri<{ht to this title. 



Dr. W. Rosenhain, F.R.S., read a paper on "The Metallurgical 

 Microscope." 



The principal requirements of the metallurgical microscope are sum- 



