ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 527 



the melts were inoculated during cooling, to prevent supercooling, to 

 which they showed a marked tendency. The existence of Fe 3 P and Fe 2 P 

 is confirmed. A comparative table of the phosphides, arsenides, and 

 antimonides of manganese, iron, cobalt, nickel, and copper, is given. 



0. Kuhn,* in preparing copper phosphide, obtained a product which 

 on solution in nitric acid, left a residue of glistening needles, insoluble 

 in nitric acid, and corresponding approximately to the formula Fe 5 P 2 . 

 The author considers this to be another definite compound, in addition 

 to the four the existence of which is admitted by Le Chatelier and 

 Wologdine. 



Decarburisation of Cast Iron by Gaseous Oxidising Agents.f — H. 

 Becker has studied the action of mixtures of carbon monoxide and 

 carbon dioxide upon cast iron at different temperatures, determining the 

 amount of decarburisation by chemical and microscopical examination. 

 The decarburisation is greater as the proportion of carbon dioxide and 

 the temperature increase. Decarburisation ceases when the proportion of 

 C0 2 falls to 30 p.c. at 800°C. to 12 p.c. at 900°C, and to 2 '85 p.c. at 

 lOOVC. White iron appears to decarburise less readily than tempered 

 cast iron at 800°C. A mixture containing 28 p.c. C0 2 will decarburise 

 cast iron at ( J00°C. without oxidising the iron noticeably. A 24 p.c. 

 C0 2 mixture acts similarly at 1000°C. 



Cementation of Steel. — F. Giolitti and L. AstorriJ find that the 

 addition of a little benzene vapour to carbon monoxide, used as a cemen- 

 tation medium, increases the concentration of carbon in the outer layers 

 of the steel. If the proportion of benzene be increased beyond a certain 

 value, carbon is deposited on the surface of the steel, and the concentra- 

 tion of carbon in the outer layer reaches the value given by solid cemen- 

 tation media. The authors have found cementation to occur when very 

 mild steel and powdered charcoal are heated to 1000°C. in a vacuum, in 

 intimate contact. 



F. Giolitti and F. Carnevali§ have studied the effect of strongly com- 

 pressing gases used in cementation. 



Improvements in Metallographical Methods. || — R. Loebe describes 

 the following new devices which he has used in determining cooling 

 curves, standardizing thermocouples and similar work. (1) A clock 

 giving audible signals at definite short equal intervals of time ; (2) a 

 modification of the wire method of taking melting points. The melting 

 of a wire of the metal under investigation, fixed across the ends of two 

 platinum wires, causes a bell to ring by breaking an electrical circuit. 

 The temperature is indicated by a thermocouple with its hot junction 

 close to the melting wire. (3) An electric ^resistance tube furnace ; 

 (4) clamps for holding a pyrometer centrally in the same furnace ; 



* Cherniker Zeitung, xxxiv. (1910) pp. 45-6. 

 f Metallurgie, vii. (1910) pp. 41-59 (17 figs.). 



% Gaz. Chim. Ital., xl. (1910) pp. 1-20, through Joum. Chem. Soc, xcviii. 

 (1910) p. 507. § Atti R Accad. Sci. Torino, xlv. (1910) pp. 337-45. 



Metallurgie, vii. (1910) pp. 5-10 (12 figs.). 



