ma1 decomposition method proves to be feasible, it will eliminate this major factor that interferes with price reduct,ion, the lack of n suitahle process of reclaiming tho contaminated scrap. All the ingenious way8 that have been proposed to produce and fabricate this gas-sensitive metal and its alloys are discussed in great detail. The physical properties of purr titanium may now be quoted ait,h considerable assurance of their validity: density, 4.505 g . / ~ m . ~ alpha-hcta ; transition temperature, 882.5'C.; melting point, 1668'C.; boiling point, 3500°K.; electrical resistivity (~.oom temp.) 42.1 X 1 0 P o h m - e m . ; etc. The mechanical properties of the pure metal (made from the iodide) are now known xsith comparable accuracy and demonstrate its inherent ductility: hardness (VPN), 80; ultimate tensile stress, 36,500 Ib./in.'; elongation, 72 per cent; reduction in area, 86.2 per cent. The hardness rapidly increases and the ductility vanishes when fractional perccntsges of oxygen, nitrogen, and (to a lesser estent) carbon are present. Addition of alloying elcment,~,on the other hand, greatly increase the strength while still retaining some durbilitp: Mallor?. Sharon titanium alloy, containing 3 per cent Al and 5 per cent Cr, has an ultimate tensile stross of 155,000 lh./in.* and an claw gation of 15 per cent. Even stronger ~ l l o yare ~ now in eommereial production and further developments may he expected. The high-temperature reactions with gases are earefullg evaluated. Titanium is a highly reactive metal, hut it is extremely resistant to corrosion by most reactive media, owing to the presence of a thin, inert film which rapidly forms when the surface is exposed to air. The work concludes with s summary of methods of preparing the titanium s~ecimensfor metalloaa~hicexaminstion. Most ol the etching re&nt,s depend an hyarofluoric acid for their specifir effects. This hook has a detailed Tnhlr of Contents and n good index. Unfortunatelv, there is no irides to t,he authors of the numerous lit,eraturo t&renees. The contents are so carefully arrangrd, however, that an," phrticulnr topic is readily located. This is hy far the best book on the metallurgy of titanium and its alloys that h z yet ~ appeared. LAURENCE S. FOSTER
0
CROP PROTECTION
G. J. Rose, Entomdogist for Micron Sprayers Limited, London. The Philosophical Library, New York, 1955. xxi 223 pp. 113 figs. 13 tables. 14.5 X 22 cm. $10.
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As IADICATED hy the puhliahers, this book is written for the cultivator and is a practical guide to the protection of crops from seed to stored product against inserts, fungus organisms, and weeds. Although the author has apparently been very thorough in oovering materials, methods, problems, and practicable solutions within his own experiences, he has not made any attempt to avoid the resultant provincialism. Because of this somewhat limited scope, t,he hook will be most useful in t h i ~country as a well-written informative reference of British practices and eqnipment rathcr than as a directly npplicahle plwtieel guide to the solutions of our awn pesGcontrol prohlems. The hook is divided into four sections: I, Formulations (48 pp.); 11, Chemicals (fi7 pp.); 111, Application Machinery (65 p p ) ; and IV, Stored Products (23 pp.). An appendix includes 13 extremely useful tables: linear, arcs, dry, volumetric, and liquid measure conversions; dilut,ions to make percentage spray solutions; conversions of parts to percentages; rates of travel; weights, liquid measures, and capacities and acreages; other useful conversions; and trees per acre with from I to 30 feet between trees. Thc index unit is very complete. Sections, I, 11, and IV provide a. good background and useful working knowledge of crop pests and crop protection. Section 111 contains useful general information but is limited to British products, with some exceptions. Only minor typographical errors were noted. F. A. GUNTHER
JOURNAL OF CHEMICAL EDUCATION, AUGUST, 1956
