ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 595 



(9) pure benzol; (10) carbon bisulphide; (11) carbon bisulphide 

 1 part plus benzol 4 parts. The preparations _ are preserved in small 

 glass jars, the lids being luted on with sodium silicate. 



Preparation of Slides for Blood Films.* — A. E. Wright states 

 that ideally perfect films can be obtained by simply rubbing the slide 

 with the finest emery-paper. The paper is mounted on a stout cylindrical 

 roller by means of a rubber ring. In making a film a drop of blood 

 is placed on a slide thus prepared ; another slide is brought down on it, 

 and as soon as the blood has spread out in the included angle the upper 

 slide is drawn along the surface of the lower. The foregoing method is 

 ill-adapted for a differential count of white corpuscles unless a line be 

 ruled with a needle longitudinally from end to end through the equa- 

 torial region of the film. The count should then proceed from one end 

 of the equator to the other. 



Shenton, J. P. — Application of the Microscope to the study of potable water. 



Trans. Manchester Micr. Soc, 1903, pp. 41-53. 



Simon, K. — Dendritic forms in paper. Tom. cit., pp. 92-5 (1 pi.). 



Metallography, etc. 



Hard and Soft States in Metals.j— G-. T. Beilby, in a paper read 

 before the Faraday Society, advances the following argument on the 

 above subject. Metals ordinarily occur in two distinct solid phases — the 

 hardened or amorphous (A phase), and the annealed or crystalline 

 (C phase). The A phase is transformed into the C phase by the agency 

 of heat ; the C phase is transformed into the A phase by mechanically 

 produced flow. In the transformations A^±C there are two interme- 

 diate mobile phases, M and M', so that the transformations may be 

 written A -» M' -» C and C -» M -> A. The author's experiments and 

 observations lead to the conclusion that mere modifications of the 

 crystalline state in respect of the arrangement and size of the crystals, 

 forming the solid mass of a particular metal, are insufficient to explain the 

 difference between its hard and solid state. He considers that the kind 

 of hardening which is due to purely mechanical force involves a process 

 the effect of which is to cause the breaking down of the crystalline con- 

 dition more or less completely, and the production of a superficial, and 

 sometimes inter-crystalline, flow of the metal, which transforms it from 

 the crystalline to the amorphous state. 



Influence of Varying Casting Temperature on the Properties of 

 Steel and Iron Castings.^ — P. Longmuir concludes, as the result of 

 prolonged microscopical research, that a suitable casting temperature for 

 any given alloy is not constant, but varies with the form and weight of 

 the casting. Other determining conditions are the rate of pouring, the 

 form of runner and gate, and the distance travelled by the metal before 

 entering the mould. By taking advantage of these determining con- 

 ditions, and commencing with a sufficiently high casting temperature, 



* Lancet, 1904, II. p. 73. 



t Electro-chemist and Metallurgist (June 1904) pp. 806-26 (5 figs, and 20 photo- 

 micrographs. 



% Iron and Steel Mag., viii. (July 1904) pp. 32-47 (20 figs.) ; Iron and Steel 

 Institute May (1904) Meeting. 



