510 SUMMARY OF CURRENT RESEARCHES RELATING TO 



substance, transparent, and free from colour. As it contains some 

 fibres it is necessary to dilute the glucose with water until it will pass 

 through a paper-iilter. The water should be driven off by heat over 

 a water-bath until the glucose is considerably thicker than xylene- 

 Ijalsam. The alcohol should be added until the glucose is of the same 

 consistence as xylene-balsam, or a little thinner. The glucose is not 

 perfectly soluble in strong alcohol, but is soluble in a mixture of water 

 and alcohol. As the glucose is hygroscopic the preparation must be 

 ringed round. 



■'o^ 



Metallography, etc. 



Foundry Irons."' — A general review of the properties of foundry 

 irons in relation to their composition and structure is given by J. E. 

 Johnson. The application of the iron-carbon equilibrium diagram to 

 the study of the phenomena shown by these alloys is first considered, 

 and then summaries are given of the influence of the more common 

 elements found in foundry irons as well as those of special alloying 

 elements. Considerable attention is devoted to the effect of oxygen, 

 which is considered to be most beneficial. Analyses of strong and weak 

 irons of otherwise similar composition showed that the strong irons 

 contained 0*05 to 0*07 p.c. oxygen, while the weak irons contained 

 practically nil. This strengthening action of oxygen is associated wdth 

 its influence on the graphite, favouring its retention in nodular or short, 

 rounded shapes, having a much less weakening effect than the long thin 

 and consequently very numerous graphite plates found in oxygen-free 

 irons. Oxygen is retained in irons when produced at a low temperature 

 in the furnace. The superiority of cold-blast charcoal irons over coke 

 irons is principally due to their higher oxygen content, owing to the 

 lower temperature of the furnace-hearth ralher than to their low sulphur 

 content. Numerous photomicrographs illustrate the different shapes in 

 which graphite occurs. It is also claimed that oxygen, like sulphur, 

 retards graphitization. 



Annealing of Arsenical Brass, t — A very thorough investigation of 

 the effects of heat treatment on the structure and mechanical properties 

 of three arsenical brasses of the following compositions : — (a) 62*41 p.c. 

 copper, 0*24: p.c. arsenic; (6) 61 "07 p.c. copper, 0*139 p.c. arsenic; 

 (c) 62 • 49 p.c. copper, 0*12 p.c. arsenic, has been made by C. H. Mathewson 

 and E. M. Thalheimer. Each of these alloys successfully withstood both 

 hot and cold working. 



In one series of heat-treatments strips of each alloy which had been 

 cold-rolled to a 50 ]).c. reduction in thickness were annealed at 450°, 

 500°, 550°, 600°, 650°, 700°, and 750° C. for fifteen minutes and then 

 quenched. This period of anneal was suflScient to develop equilibrium 

 quantities of the two constituents at the respective temperatures. 

 The mechanical properties and photomicrographs of the structure 

 characteristic of each alloy at these temperatures are given. The 

 mechanical tests show a maximum ductility and minimum tensile strength 



* Met. and Chem. Engineering, xv. (1916) Nos. 9, 10, 11, 12 (34 figs.). 

 t Journ. Inst. Metals, xvi. (1916, 2) pp. 18-65 (45 figs.). 



