ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 261 



comparison is made between the three metals of the iron group in their 

 behaviour with aluminium. 



Binary Alloys of Calcium.* — The electrolytic production of pare 

 metallic calcium in large quantities has rendered the study of its alloys 

 possible. L. Doriski has investigated its alloys with zinc, cadmium, 

 aluminium, thallium, lead, tin, bismuth, antimony, and copper, and 

 gives incomplete equilibrium diagrams. Owing to the powerful 

 affinity of calcium for oxygen, the great amount of heat evolved 

 when calcium is dissolved in molten metals (causing an explosive 

 reaction in some cases), and the destructive action of high calcium 

 alloys on the Jena glass and porcelain tubes used, the alloys were pre- 

 pared only with great difficulty. Some of the high calcium alloys 

 were melted in vacuo. Most of those of low calcium content were 

 prepared by dropping calcium in small amounts into the metal heated 

 considerably above its melting-point. Calcium is remarkable for its 

 readiness to form compounds. The following were found : — CaZn u „ 

 CaZn 4 , Ca 2 Zn 3 , CaZn (?), Ca 4 Zn, CaCd 3 , CaCd, Ca 3 Cd, (?), CaAl 3 , CaTl 3 , 

 CaTl (?), CaPb 3 , CaSn 3 . Compounds with antimony and bismuth pro- 

 bably exist. Microscopic examination confirmed the diagrams deduced 

 from thermal analysis. 



Impact-testing on Notched Test-pieces. f — Ehrensberger considers 

 this to be a useful addition to testing methods, affording additional 

 information on mechanical properties, and makes the following re- 

 commendations as the result of an investigation of the test. The 

 machine to be a Charpy pendulum, one of three types giving respectively 

 250, 75, and 10 kilogram-metres striking energy. In the test-piece 

 160 x 30 x 30 mm. a hole 4 mm. diam. is drilled in the centre of the 

 length, parallel to one face and 15 mm. distant from it ; a cut is made 

 from the hole to the opposite side. A rounded notch is thus produced. 

 The width of test-pieces cut from plates and similar material may be less 

 than 30 mm. The test-pieces are machined cold, and must not after- 

 wards be heated. The results to be expressed as energy absorbed per 

 square centimetre (" spezifische Schlagarbeit "). The test-piece to be 

 completely broken. The numerous diagrams and tables of tests on 

 different steels with variously shaped notches show the necessity for 

 standardisation of methods. 



Constitution of Manganese Cast Irons. J — L. Guillet retracts his 

 former statement that cast irons of high manganese content do not 

 contain y-iron. What appeared to be pearlite was, in fact, the eutectic 

 mixed crystals-cementite. The addition of nickel or manganese to cast 

 iron in sufficient quantity produces y-iron. In the case of a grey iron 

 the addition of manganese produces y-iron before the graphite has dis- 

 ppeared. Increase in manganese is accompanied by an increase in 

 amount of carbide. 



■> 



Zeitschr. Anorg. Ghem., lvii. (1908) pp. 185-219 (8 figs.). 



t Stahl und Eisen, xxvii. (1907) pp. 1797-1809, 1833-9 (19 figs.). (Report of 

 committee appointed by the German Association for Testing Materials to inves- 

 tigate this method of testing.) 



\ Gomptes Rendus, cxlvi. (1908) pp. 74-5. 



