INDUSTRIAL a n d ENGINEERING CHEMISTRY ANALYTICAL EDITION V O LU M E 18, N U M B E R 4 IS S U E D A P R IL 25, 1946 CONSECUTIVE NUMBERS EDITOR: WALTER J. MURPHY Assistant to Editor: N. A . PARKINSON Associate Editor: L A W R E N C E T. HALLETT Contributing Editor: R. H. MULLER Assistant Editors Manuscript Editing: G . GLADYS GORDON Manuscript Reviewing: STELLA ANDERSON Make-up: CHARLOTTE C. SAYRE Advisory Board R. P. C H A P M A N T. R. C U N N IN G H A M R. H . M U LLER J . R. C H U R C H IL L G . E. F. LU N D ELL B. L. O S ER B. L. C LA R K E M. G. MELLON H. H. WILLARD — Ed ito ria ls................................ 217 Colorimetric Determination of Cobalt with Ammonium Thiocyanate............................R. S. Youns and A . J. Hall 264 Optical Methods in Electrophoresis . L. G. Longsworth 219 Most Economic Sampling for Chemical A n a ly s is ................. C. West Churchman 267 Deproteinization by Metaphosphoric A cid — Review of Its Value for A n a l y s t ......................................A. A. Horvath 229 Drill Sampling Device for Fish Livers. Precision and A c ­ curacy ..........................F. B. Sanford and G. C. Bucher 269 Application of Platinum Resistance Thermometry to Some Industrial Physicochemical Problems . Daniel R. Stull 234 MICROCHEMISTRY Volumetric Quantitative Determination of— S O O N a Group Colorimetric Determination of p,p'-DDT in Technical DDT in Sodium Benzene Sulfinate.....................Leo Ackerman 243 Saul W. Chaikin 272 Determination of 1,2-Propylene Glycol in Ethylene Glycol . Semimicrodetermination of Saponification Equivalent by R. C . Reinke and E. N. Luce 244 Rieman’s Double-Indicator Method . Donald Ketchum 273 Estimation of Salts of Weak A cids by Direct Titration in Mixed Solvent.................... Santi R. Palit 246 NOTES ON ANALYTICAL PROCEDURES Determining Moisture Equilibrium Curves of Hygroscopic Isopropyl Alcohol in Cotton Wax Determination .... M aterials.................................................Willmer A . Wink 251 James H. Kettering 275 Simultaneous Determination of Ethylene and 1,2-Propylene Preparation of Silica Gel for Chromatography................. Glycols .... Benj. Warshowsky and Philip J. Elving 253 Roberta Harris and Arne N . W ick 276 Determination of Small Amounts of 4-Vinyl-1-cyclo- Colorimetric Determination of Iron in Presence of Large Con­ hexene (Butadiene Dimer) in Tetrahydrophthalic A n ­ centrations of Copper and Nickel . R. H. Greenburg 255 hydride . Benj. Warshowsky and Philip J. Elving 276 Destruction of Organic Matter in Blood Fibrin and Chroma- Distilling Apparatus for Production of Pure Water . cized Medical Catgut by Wet O xidation ........................ Frederic E. Holmes 277 G . Frederick Smith 257 Regeneration of Walden Silver Reductor............................. Analysis of Mixtures of Meta- and Para-Cresols and Their Eugene H . Huffman 278 Butylated Products . Donald R. Stevens and J. E. Nickels 260 New Type of Reflux Condenser. Willard T. Somerville 278 Determination of Cobalt in High-Cobalt Products. Separa­ tion from Iron by Phosphate . R. S. Young and A . J. Hall 262 Instrumentation in Analysis . R. H. Muller (Advt. Sect.) 25 The American Chemical Society assumes no responsibility for the statements and We acknowledge with thanks the action of J. T. Baker Chemical Co. in releasing the front cover of this issue for editorial purposes. opinions advanced by contributors to its publications. V iew s expressed in the editorials are those of the editors and do not necessarily represent the official position Copyright 1946 by American Chemical Society. of the American Chemical Society. 37,200 copiés of this issue printed. 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For their routine check on silica in the raws,. many cement companies employ a time- saving method which involves the use of Baker’s Analyzed C.P. Perchloric Acid. The extremely low content of silica and non-volatile matter in this acid makes it preferable for many other tests as well. Baker’s Analyzed C.P. Ammonium Oxalate is often the chemist’s choice for calcium determination. This reagent is extremely low in non-soluble, non-Volatile and sulphate materials. Baker’s Analyzed C.P. Chemicals differ from other laboratory chemicals. They have the actual analysis on the label—not mere maximum limits of impurities. This saves the chemist time when making computations. Baker s distributors welcome every opportunity to serve the cement industry. 'When you Purity defined —not to order your reagent chemicals from your favorite supplier, be sure to specify "Baker’s “ maximum limits“—but to Analyzed.” t h e decimal by actual lot analysis. That’s the story of j. T. Baker Chemical Co., Executive Offices and Plant: Phillipsburg, the Baker's Analyzed label. N. J. Branch Offices: New York, Philadelphia, Boston and Chicago April, 1946 ANALYTICAL EDITION 5 TODD SCIENTIFIC SPECIFICATIONS PRECISE FRACTIONATION ASSEMBLY USED BY THE NATIONAL BUREAU OF STANDARDS An efficient and versatile laboratory fractionation column assembly with a new method of adiabatic temperature control for complete fractionation of many types of organic licpiid mix­ tures either at atmospheric pressure or under vacuum. Covered by United States patent No. 2,387,479. FEATURES: 1. Fractionation efficiency up to 50 theoretical plates. 2. Fractionation charges from 2 ce. to 5000 cc. inclusive. 3. Temperature range from room temperature to 100°C. (752°F .). ■I. New precision device for adiabatic tem perature control. 5. Atmospheric or vacuum fractionations. 6. Three interchangeable fractionating columns. 7. Improved spiral packing for small column. 1!. Rapid fractionation with complete visahilily. 9. Easily operated with a m inim um of experience. 10. Special machined supports for assembling apparatus. 11. Precision control panel for operating the colum n’s ‘•Stag­ gered Dual Heating Unit” and still pot. 12. Special aluminum alloy pot heater with low temperature lag . 13. All metal parts non-corrosive to normal laboratory atm os­ p h e re . II. Rapidly •assembled or dismantled. This FRACTIONATION COLUMN ASSEMBLY is the result of a comprehensive and critical study of practically all significant reports on methods and apparatus for precise laboratory fractionations which were published in the United States, British, French, and German scientific literature. In addition, the methods and apparatus surveyed have been subjected to exhaustive exjierimental tests in our laboratories. These tests have shown the need for a versatile and efficient fractionation apparatus of more practical design to meet the varied fractionation requirements arising in chemical laboratories. To meet this need, a new, truly versatile and highly efficient laboratory fractionation column assembly was developed with several practical features which enable this single assembly to eliminate the use of a number of fractionation units for solving different problems. The use of the recommended packings in the three interchangeable columns of this new assembly gives unusually high fractionation efficiencies over comparatively wide rates of boiling either at atmospheric pressure or under vacuum. These particular packings eliminate the frequent disadvantages of the use of precise reflux ratio control PARTIAL LIST OF USERS: devices which are invariably bulky, tedious to operate, and frequently have large American Cyanamid Co.. Bound Brook, N.