ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 633 



reduced hsematin or hreinochromogen, which by the action of the 

 chlorin-water becomes chlorohasmatin. 



Ammonium sulphide in excess was found to favour the production 

 of haemochromogen crystals. 



Bouvier, E. L. — Recolte et conservation des Dipteres particulierement des especes 

 qui piquent pour sucer le sang. 



[Gives a lucid account of how to collect, mount, and preserve biting and 

 blood-sucking Diptera.] 



Garner, J. B., & W. E. King — Germicidal Action of Potassium Perman- 

 ganate. 



[Experiments showing that this reagent is antiseptic and germicidal in 

 less quantities than those given by Miguel and Jager.] 



Amer. Chem. Joum., xxxv. (1906) pp. 144-7. 



Metallography, etc. 



Special Brasses.* — This valuable contribution to the study of alloys 

 of copper, zinc, and a third element, by L. Guillet, is a continuation of 

 his previous work on brasses. f When the third element is introduced 

 it first enters into solution in one or more of the constituents of the 

 copper-zinc alloy. At a certain percentage of the added element satura- 

 tion is reached and a special constituent is formed. Below this saturation 

 point the third element may be considered as equivalent to so much 

 zinc, the alloy formed having properties nearly the same as an alloy of a 

 definite percentage of zinc with copper. The composition of the copper- 

 zinc alloy to which any given ternary alloy is considered to be equivalent, 

 can be determined by microscopic examination. From observations of 

 this kind on alloys containing different amounts of the third element 

 the coefficient of • equivalence can be calculated. This is the percentage 

 of zinc to which 1 p.c. of the added element is equivalent. As an instance, 

 take an alloy, Cu 70 ; Zn 28 ; Al 2. The coefficient of equivalence of 

 aluminium is 6. The alloy therefore may be considered as Cu 70 ; 

 Zn 28 + 12. Beducing this to percentage composition, it becomes 

 Cu 63 "63 ; Zn 36 "37. The properties of a ternary alloy are not iden- 

 tical with those of its equivalent copper-zinc alloy. 



The author has worked out the application of this law in detail for 

 a large number of brasses containing one or more of the following 

 elements : aluminium, manganese, iron, tin, lead, silicon, magnesium, 

 antimony, phosphorus, cadmium. More than 500 samples were examined. 

 The practical work on the alloys included determinations of (1) micro- 

 structure — the etching re-agent employed was ferric chloride in hydro- 

 chloric acid ; (2) mechanical properties — tensile, shock, and hardness 

 tests ; (3) forging qualities, hot and cold. The alloys were all examined 

 as cast. For comparison the properties of the copper-zinc alloys were 

 determined. Aluminium and manganese will dissolve in the a and (3 

 constituents of brass in large quantities. Coefficients of equivalence are 

 as foUows : Al = 6, Mn = 0'5, Fe = 0*9, Sn = 2, Fb =1, Si = 10, 



* Rev. Metallurgie, iii. (1906) pp. 243-88 (59 photomicrographs). 

 t Op. cit., ii. (1905) pp. 97-120. 



Oct. 17th, 1906 2 t 



