ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 383 



by engineers for steel castings. With iron and carbon castings the 

 ductility demanded can be ensured with ease, but with such ductility 

 it is impossible to correlate the required tenacity. The latter property, 

 it is true, can be obtained from iron and carbon castings, but at the 

 expense of an almost complete loss of ductility. 



Alloys of Copper and Tin.* — W. Campbell, in a paper read before 

 the Institution of Mechanical Engineers, f divides these alloys into 

 seven classes according to their percentage of copper. The paper is 

 illustrated by an excellent series of photographs, from which it appears 

 that the branch e in the Roberts-Austen freezing-point curve of copper- 

 tin alloys must be one of change in the solid. When the many and 

 distinct different structures in the series, produced by quenching at 

 different temperatures, and by reheating and then quenching, are con- 

 sidered, it is quite evident that the changes which take place during the 

 cooling of a copper-tin alloy, especially in the neighbourhood of the 

 second eutectic, are even more numerous than those of the carbon- 

 irons. 



Bibliography. 



Grijns, G. — Eine einfache Vorrichtung, tim zu verhindern, dass beim Gebrauch 

 des Briitapparates fur konstante niedrige Temperatur, System Lautenschlager, 

 wenn das Eis im Behalter ausgeht, das ungektihlte Wasser in den kalten 

 Schrank fliesst. 



CentraTbl. Bald., l te Abt. Orig., XXXI. (1902) pp. 430-2 (3 figs.). 



Hunziker, O. F. — Review of existing Methods for Cultivating Anaerobic Bacteria. 



Journ. App. Micr., V. (1902) pp. 1(594-7, 1741-58, 1800-13 (54 figs.). 



Kaiser, W. — Die Technik des modernen Mikroskopes. 2. ganzlich umgearbeitete 



Auflage, 8vo, mit vielen Abbildungen. (Technique of the Modern Microscope. 



Second and completely revised edition, with numerous illustrations.) 



Vienna, Pertes, 1901. 



Weissenberg, H. — Ein registrierender Bakterien-Spirometer. (An apparatus for 

 registering the evolution of nitrogen by denitrifying bacteria.) 



CentralblBald., 2 te Abt., VIII. (1902) pp. 370-7 (2 figs). 



* Nature, No. 1685, pp. 354-6 (10 figs.). f December 20, 1901. 



l 2 'I 



