ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 



paration of tlie steels contained 32 p.c. boron, and was made in the 

 electric furnace from calcium borate. Boron raises the thermal critical 

 points of steel. The special constituent (boro-carbide of iron) may be 

 caused to disappear by heating above 850° C, followed by quench- 

 ing, but with increase of boron-content the difficulty of thus dissolving 

 the boro-carbide increases. The presence of this body causes brittleness, 

 and is accordingly objectionable. It is only in the quenched state that 

 these steels appear to be suitable for any industrial application, A boron 

 content of (V5 p.c. gives the most interesting results. 



Copper Steels.* — P. Breuil has previously published results of his 

 work on these alloys.t The present complete account contains much 

 new matter. Four series were examined, containing carbon about 

 0*15, 0"o5, 0'65, and 1*0 p.c, copper in each series increasing from 

 • 5-30 p.c. Ar 3 and Ar 2 are lowered by the presence of copper in soft 

 steels. In medium carbon steel Ar 1 is lowered, but not below 550° C. 

 The position of Ar 1 in hard steels is not affected. Tensile strength 

 increases with copper content — copper thus has an effect comparable with 

 that of nickel ; resistance to shock is good. Copper steels are com- 

 mercially serviceable up to about 4 p.c. copper ; no segregation occurs 

 below this limit. Free copper occurs in the steels containing more than 

 8 p.c. copper. Talc was used in place of alumina as the polishing powder 

 for micro-specimens. Move than 100 photomicrographs are given. 



Cast Iron as Cast- and Heat-treated. | — W. H. Hatfield has 

 attempted to locate the regions of temperature in which the carbide of 

 iron breaks up into iron and carbon. Test bars of a white iron con- 

 taining 3 • 4 p.c. carbon (all combined), 1 • 1 p.c. silicon, were cast in 

 sand, and were heated together in an annealing oven. One bar was 

 cooled in air, and one quenched in water when the temperature had risen 

 to (1) 780^0., (2) 820° C, (3) 860° C, (4) not higher than 000" C. and 

 cooled extremely slowly (a) to 750° C, (b) to 650° C. As regards distribu^ 

 tion of annealing carbon, the quenched bars differed little from the 

 air-cooled bars. Sections from all the bars were microscopically 

 examined. Annealing carbon first appeared in the bars cooled from 

 820°C., and increased progressively in the subsequently cooled specimens. 

 The massive cementite appeared to decompose between 800° and 900° C, 

 while the bulk of the pearUte disappeared during cooling from 750°— 

 650° C, giving ferrite and temper carbon. From his experiments on 

 influence of casting temperature, the author concludes that while great 

 variation in strength is found between cast irons of the same com- 

 position as cast, there is no direct relation between strength and casting 

 temperature. 



Non-Metallic Impurities in Steel. § — By microscopical and chemical 

 methods, E. F. Law has demonstrated the existence in steel of sulphide,, 

 silicate, and oxide of iron, sulphide and silicate of manganese. 

 Sulphide of iron is rarely found in commercial steels, the sulphur existing, 



* Journ. Iron and Steel Inst., Ixxiv. (1907) pp. 1-78 (16 figs., 10 pis.). 

 t See this Journal, 1906, pp. 516 and 7'±0. 

 + Tom. cit., pp. 79-93 (23 figs.). 

 § Tom. cit., pp. 94-105 (11 figs.). 



