ZOOLOGY AND BOTANY, MICROSCOPY, KTC. 123 



broad. There is an arrangement for closing the front of the notch by 

 a large cover-glass, and the back is closed by a milk-glass scale, e.g. a 

 fragment of an old thermometer-scale. The notch thus forms a trough 

 of suitable shape, and its metal surroundings, being pivoted by two 

 screws on a suitable frame, materially assist in procuring a perpendicular 

 position, to which a circular level contributes. This frame is prolonged 

 into a tripod foot, and can be raised or lowered. The observation part 

 of the apparatus is one of Zeiss' Braus-Driihner preparation Microscopes, 

 and this is directed on to one of the divisions of the glass scale. When 

 the organism has reached this division a stop-watch is released, and the 

 time of reaching the next division recorded. The author hopes at some 

 future time to publish an account of his researches. 



Metallography, etc. 



Polymorphism of Zinc* — C. Benedicks has determined the electrical 

 resistance of samples of pure and commercial zinc, at small temperature 

 intervals, between 16° 0. and the melting-point. The existence of a 

 transformation-point at about 8-40° C, discovered by Le Chatelier, was 

 confirmed, and a similar point was found at about 170° C. The author 

 concludes that zinc is trimorphous, the a form being stable up to 170° C, 

 /? in the range 170° to 830° C, y from 330° to 41!) -4 C°. Abnormal 

 results were given by the impure samples. 



Aluminium-calcium Alloys. f — From the results of determinations 

 of electro-chemical potential and electrical conductivity of a series of 

 aluminium-calcium alloys, J. M. Breckenridge deduces the existence of 

 the compound Al 3 Ca. 



Alloys of Lithium.:}: — G. Masing and G. Tammann have studied the 

 binary systems of which the components are lithium and one of the 

 metals sodium, potassium, tin, cadmium, and magnesium. By using 

 very thin thermocouple wires and protecting tubes, it is possible to apply 

 the methods of thermal analysis to a few grams of material, and thus 

 to work out equilibrium diagrams of systems of metals which can be 

 obtained in a pure state only in small amounts. The original should be 

 consulted for the detailed results of the investigation. 



Gold-magnesium Alloys. § — G. G. Urasow and R. Vogel explain 

 differences in the equilibrium diagrams obtained by them when working 

 independently. The existence of Au 2 Mg s is confirmed, but it is stable 

 only in the range 79(i°-71(i° C, breaking up into AuMg 2 and AuMg 3 at 

 the lower temperature. 



Silver-cadmium Alloys. || — G. Bruni and E. Quercigh have deter- 

 mined the equilibrium diagram by means of cooling curves of 30 alloys. 

 The compounds AgCd and AgCd 4 occur ; these form solid solutions with 

 silver, or cadmium, or each other, according to the composition of the 

 alloy. 



* Metallurgie, vii. (1910) pp. 531-7 (5 figs.). 



+ Met. and Chem. Eng., viii. (1910) p. 349. 



% Zeitschr. Anorg. Chem., lxvii. (1910) pp. 183-99 (5 figs.). 



§ Tom. cit., pp. 442-7 (4 figs.). || Tom. cit., pp. 198-206 (3 figs.). 



