ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 219 



were obtained ; they were rendered homogeneous by annealing at 

 1250° C. At 30 p.c. molybdenum a eutectic appeared. In alloys 

 containing 4o p.c. or more molybdenum a compound MoCo was observed 

 as long needles. Primary molybdenum, or a solid solution, was found 

 at concentrations exceeding 65 p.c. as small rounded masses enclosed 

 in crystals of MoCo. 



Silicon in Arsenical Copper.* — F. Johnson has studied the effect 

 of silicon when used to deoxidize arsenical copper, and describes the 

 micro-structures of specimens containing varying small amounts of 

 arsenic, silicon, iron, and oxygen. The deoxidized specimens contained 

 no cuprous-oxide globules, and the arsenic, silicon, and iron were present 

 in solid solution in the copper. When specimens containing oxygen 

 were annealed in hydrogen, the blue cuprous-oxide globules became 

 black, the oxide being reduced to metallic copper. 



Manganese-cobalt Alloys.f — K. Hiege finds that manganese and 

 cobalt form a continuous series of solid solutions. Alloys containing 

 more than 40 p.c. cobalt showed a cored structure, which was removed 

 by annealing at 1000° C , except in the case of the alloy containing 

 90 p.c. cobalt : this still showed a want of homogeneity. Manganese- 

 rich alloys were etched with 8 p.c. acetic acid, and cobalt-rich alloys 

 with hydrochloric acid. 



Lead-tin-antimony and Tin-antimony-copper Alloys. } — W. Camp- 

 bell discusses the constitution of the alloys of these two ternary systems, 

 and describes their micro-structure in some detail. In the alloys are 

 found crystals and dendrites of antimony, SbSn, Cu 3 Sn, CuSn, lead, 

 and a-tin set in a more or less plastic ground mass, which may be com- 

 posed of Pb-SbSn, Pb-Sna or CuSn-Sna. The crystals and dendrites 

 and the ground mass vary in hardness and plasticity : thus by varying 

 the composition the physical properties may be controlled. Antimony 

 and SbSn are lighter than the liquids out of which they freeze and tend 

 to concentrate in the upper part of the ingot. '2 p.c. nitric acid in 

 alcohol was found to be a good etching reagent for the lead-tin-antimony 

 alloys. 



Alloys of Zinc, Tin, and Cadmium. §— R. Lorenz and D. Plum- 

 bridge have studied the three binary systems and the ternary system 

 formed by zinc, tin, and cadmium, and give a number of photomicro- 

 graphs illustrating the structure of the alloys. The few solid solutions 

 occurring are of very low concentration. Hydrochloric acid in alcohol 

 was used for etching. 



Thallium-bismuth Alloys. || — X. Kurnakow, S. Zemczuzny, and 

 V. Tararin give an account of their exhaustive revision of the equili- 



* Journ Inst. Metals, x. (1933, 2) pp. 275-303 (11 figs.). 

 + Zeitschr. Anorg. Chem., lxxxiii. (1913) pp. 253-6 (8 figs.). 

 J Proc. Amer. Soc. for Testing Materials, xiji. (1913) pp. 630-68 (24 photo- 

 micrographs). 



§ Zeitschr. Anorg. Chem., lxxxiii. (1913) pp. 228-42 (24 figs.). 

 Zeitschr. Anorg. Chem., lxxxiii. (1913) pp. 200-27 (16 figs.). 



