ZOOLOGY AND BOTANY, MICROSCOPY, ETC. Gil 



of iron. The best way of treating a specimen is to heat the polished 

 metal upon a hot plato until it assumes a tint purple to the naked eye. 

 The various constituents oxidise at different rates, and assume corre- 

 sponding coloured films. Heated in this way pearlite assumes a blue 

 tint with brown-red worm-like layers of carbide of iron, and the phos- 

 phide of iron a pale yellow colour. The sulphides do not apparently 

 change colour, but are easily detected, as they appear of a slate colour. 



The phosphides seem to occur in the eutectics as Fe 3 P and as a 

 definite chemical compound. 



Present Position of the Solution Theory of Carburised Iron.* — A. 

 Stansfield's conclusions are : — 



(1) That carbon is less soluble in iron when presented in the form 

 of graphite than when presented in the form of cementite. 



(2) That the apparent reversal of this in steel is due partly to the 

 absence of nuclei of graphite on which further deposits might take 

 place ; partly to the length of time required for the separation of the 

 graphite, involving as it does the gradual passage of carbon through 

 the iron to reach the nuclei ; and partly to the mechanical pressure 

 which must oppose the formation of graphite in solid steel. 



Casting on Mica of Metallographic Preparations.! — H. T. Hannover 

 has found that, in obtaining soft alloys for microscopical examination, it 

 is an excellent plan to pour but the melted mass on a plate of mica 

 instead of upon a plate of glass. The trouble arising from the liability 

 of the glass to crack is in this way avoided. 



Bibliography. 



Arnold, J. 0. — The Internal Architecture of Steel. 



Metallographist, Oct. 1900, pp. 267-75 (6 figs.). 



Dommergde, G. — Traite pratique d' analyse chimique microscopique et bacterio- 

 logique des urines. Paris, 1900. 



Fay, H. — Segregation of Phosphorus in a Piece of Cold Rolled Shafting. 

 -jg [Describes how a fracture could be satisfactorily traced to this cause.] 



Metallographist, April 1901, pp. 115-9 (2 figs.). 



Kbiedmann, E. — Physikalisches Verfahren zur Einstellung von Celloidinobjeekten 



im Mikvotom. 



[Physical metiiod applied to the adjustment of celloidin objects in the micro- 

 tome.] Zeit. wiss. Mikr., XVIII. (1901) pp. 14-8 (1 fig.). 



Kaiser, W. — Die Technik des modernen Mikroskopes. 



Vienna (Perles), 1900, 80 pp. 



Kratschner & Senft — Mikroskopische und Chemische Untersuehung der 

 Harnsedimente. (Microscopical aud'Chemical Examination of Urine Sediments.) 



Vienna (Safar), 1901, 42 pp. and 13 pis. 



Linde, Dr. O— Das Messen mikroskopischer Objekte. (The Measurement of 

 Microscopical Objects.) 



A reprint from the Apotheker-Zeitung (Denter and Nicholas), 



Berlin, 9 pp. and 2 figs. 



Meyer, Arthur — Die Grundlagen und die Methoden fur die mikroskopische 

 Untersuehung von Pflanzenpulvern. Jena (Fischer), 8 pis. 



* Metallographist, 1900, pp. 300-14 (4 figs.). 

 t Op. cit., 1901, pp. 29-30 (1 fig.). 



