V O L U M E 20, NO. 10, O C T O B E R 1 9 4 8 other scientific research. The biological applications are stressed, b u t the discussion is naive and misleading. T h e many usee of the electron microscope in chemistry, metallurgy, mineralogy, ceramics, etc., are practically ignored. With the exception of a short chapter on the scanning microscope a n d on methods of analysis using the electron microscope, the remainder of the book is speculative in nature, discussing t h e ultimate limit of the electron microscope and methods b y which i t m a y be possible to improve the resolving power. A suggestion of the author’s is given a very lengthy treatment which is completely out of character with the rest of t h e book. Included in this chapter is also a brief evaluation of the proton microscope, which appears t o be careful and accurate. T h e book concludes with a n appendix of the diffraction theory of the electron microscope, in which t h e Abbe theory is discussed rather carefully with the modifications t h a t must be made on applying i t to the electron microscope. This book is highly recommended to the reader who desires to gain a n insight into the present status of research on the electron microscope without searching the very widespread literature. I t is not recommended to the reader who is interested in evaluating the usefulness of the electron microscope in a specific research problem, nor to the microscopist who is interested in the manipulation of the instrument. JAMESHILLIER
989 Synthetic Methods of Organic Chemistry. W . TheiZheimer. Vol. I, 1942-44. x -k 254 pages. Interscience Publishers, Inc., 215 Fourth A m . , New York 3, N. Y . , 1948. Price $5. This is a n extremely accurate translation of Theilheimer’s “Synthetische Methoden der Organischen Chemie,” Repertorium I , in which t h e equations are identical t o those appearing in t h e original German text. There are no significant deviations in t h e translation. A few errors have been introduced as, for example, in No. 23, page 7, where aminoacridone should read aminoacrine and where t h e ChemicaZ Abstracts reference, which has been substituted for t h e Chemische ZentraZbZatt reference in t h e original, is wrong. As t h e system employed is unique and not easily followed for t h e first time, this translation is of real value, especially t o t h e beginning researcher in this field. This and t h e subsequent proposed volumes form a valuable adjunct t o existing books on preparative organic chemistry. [The second volume in t h e German text (“Synthetische Methoden der Organischen Chemie,” Repertorium 11, by 7.77. Theilheimer, S.Karger, Basel, Switzerland, and New York, N. Y., 1948) has recently been published.] I t permits a rapid search t o be made for possible modifications of older methods or new procedures for conducting a specified chemical transformation. This and subsequent volumes should be available for reference t o every practicing organic HARRYS. MOSHER chemist.
Analysis of Cemented Carbide Compositions SIR: While I have read with interest t h e article entitled “Analysis of Cemented Carbide Compositions” b y Touhey a n d Redmond [ANAL.CHEM.,20, 202-6 (1948)], I find several important disagreements between t h e procedure described and t h e literature on t h e subject and its practical application t o t h e analytical work on cemented carbide alloys in this laboratory. 1. Our tests show t h a t molybdenum is precipitated t o a large ext e n t by cupferron in a tartaric acid solution a n d t h a t it is completely precipitated in most other acid solutions. I t is volatilized partially when ignited a t temperatures over 525’ C. when combined with tantalum, columbium, titanium, and tungsten. When present alone, i t is extremely volatile a t high temperatures. T h e authors show no d a t a indic’ating t h a t molybdenum was actually present in their test alloy. 2. I n t h e paragraph starting “ F u m e filtrate 11” it is suggested t h a t a n ignited precipitate containing oxides of titanium, columbium, tantalum, and iron be fused with potassium carbonate and t h e resulting solution filtered. T h e assumption thereafter seems t o be t h a t the tantalum and columbium will remain insoluble. This is contrary t o our experience and t o t h e published literature. A sodium carbonate fusion will cause t h e tantalum and columbium to remain insoluble, while a potassium carbonate fusion will result in solution of a large p a r t of t h e tantalum and columbium oxides. 3. T h e authors suggest (page 203) t h a t a solution containing cinchone and 10 nil. of nitric acid be evaporated t o fumes of perchloric acid. Our experience has been t h a t this evaporation is extremely hazardous. While danger of a perchloric acid explosion during oxidation of cinchonine probably depends on t h e exact technique employed during t h e e n p o r a t i o n , t h e only two accidents of this type in our laboratory occurred during t h e oxidation of cinchonine with nitric a n d perchloric acids. W e have therefore discontinued attempting this particular oxidation. Although we h a r e made no analyses following t h e scheme of Touhey a n d Redmond, our experience with similar materials causes us t o doubt seriously t h e soundness of t h e separations mentioned above. W. C. BOWDEX, JR. Ledoux and Co., Inc. New York 13, N. Y . SIR: T h e authors have carried out further tests following Mr. Bowden’s criticism of t h e separation of titanium, tantalum, colum-
bium, and iron from chromium and vanadium. T h e criticism is justified in t h a t t h e separation is not satisfactory and t h e authors appreciate this being called to their attention. T h e separation was provided (though inadvertently not so stated in t h e article) t o cover only t h e very special case where chromium and vanadium are present. We know of no compositions now on t h e market which contain either element. I t was pointed out t h a t t h e procedure is modified according t o t h e elements known t o be present, on t h e basis of spectrographic analysis or other information. Because these elements were known t o be absent from t h e test mixtures, t h e separation under discussion was not used in obtaining t h e results shown in t h e paper. Accordingl>-, t h e steps beginning on page 204, first full paragraph, lines 11t o 15, should be eliminated T h e following separation should be substituted when chromium and vanadium are present: Fuse the ignited oxides of titanium, columbium, tantalum, and iron with 8 t o 10 grams of C.P. potassium pyrosulfate and when the melt is cool, dissolve t h e melt in 50 ml. of water and 10 inl. of hydrochloric acid. Precipitate t h e titanium, columbium, tantalum, and iron by t h e addition of t h e solution to a dilute sodium hydroxide solution (10%). Add 1 gram of sodium peroxide, boil t h e solution for 3 minutes, and allow t h e precipitate t o settle after the addition of ashless paper pulp. Filter t h e precipitate, using a No. 40 Whatman paper, and wash t h e precipitate well with a dilute sodium hydroxide solution. T h e chromium and vanadium are then determined by t h e individual procedures given for these elements. T h e analysis of these complex materials is very difficult. There is much room for improved methods. In connection n-ith t h e point raised regarding evaporation, it should be noted t h a t t h e solution is first reduced in volume before fuming. T h e reduction in volume is a t low heat, under which conditions t h e cinchone is evidently sufficiently oxidlsed. I n over 4 years of t h e use of this procedure no explosion or even violent reaction has occurred. W. 0. TOUHEY J. C. REDMOND Kennametal, Inc. Latrobe, Pa.
