B R I E F S

Spectrophotometry Determination of Rare Earth Metals with 4-(2-Pyridylazo)resorcinol

Conditions, range of adherence to Beer's law, effect of pH, effect of excess reagent, sensitivity, and interferences are reported.

K A I L A S H N . M U N S H I and A R U N K. DEY, Chemical Labora­tories, University of A l lahabad, A l lahabad, India

Ana l . Chem. 36, 2003 (1964)

Calculations of the Partial Specific Volumes of the Constituents of Ternary Systems from Density Measurements

The partial specific volumes of three components of a ternary system are calculated by differentiation of an em­pirical equation which describes the total specific volume of a ternary mixture as a function of composition.

G . E. M O L A U , Polymer and Chemicals Research Laboratory, The Dow Chemical Co. , Mid land, Mich.

Ana l . Chem. 36, 2004 (1964)

Dissolved Oxygen Measurement by Constant-Potential Derivative Coulometry

The coulometric cell used has a working electrode com­posed of tiny metal spheres packed inside a porous ce­ramic tube. Results of oxygen measurements agree with concentration values established by other methods.

EDGAR L. ECKFELDT and E. W . SHAFFER, Jr. R&D Center, Leeds and Northrup Co. , North Wales , Pa.

Ana l . Chem. 36, 2008 (1964)

Microdetermination of Selenium with 3,3'-Diaminobenzidine by the Ring Oven Technique and Its Application to Air Pollution Studies

The average relative error for the method is 5% when ap­plied to selenium in the range of 0.1 to 0.5 μg. Effects of possible interfering ions were studied.

PHILIP W . WEST and C H . C I M E R M A N Coates Chemical Lab­oratories, Louisiana State University, Baton Rouge, La.

Ana l . Chem. 36, 2013 (1964)

Determination of Diethyl Sulfate. Ethyl Hydrogen Sulfate, and Sulfuric Acid in Mixtures

Ethyl hydrogen sulfate and sulfuric acid are determined by nonaqueous titration with tetrabutylammonium hy­droxide using pyridine as a solvent. Diethyl sulfate is hydrolyzed at 130° C. and the sulfuric acid formed is titrated with aqueous base.

D. K. BANERJEE, M . J . FULLER, and H . Y. C H E N , Research Di­vision, U. S. Industrial Chemicals Co. , Cincinnati , Ohio

Ana l . Chem. 36, 2016 (1964)

HENGAR GRANULES prevent "bumping" of boiling liquids Two or three insoluble Henga r Granules in the flask or test tube prevent superheat ing, with its erra t ic and dangerous "bumping" vaporization.

Won ' t con tamina te solution; speeds distillation; pre­vents boiling losses; gives sha rp fractions; reduces flask breakage .

Two types : Plain, for any lab procedure involving boiling; Selenized, for Kjeldahl ni t rogen de termina­tion. P l a i n : 100 grams $1; 250 grams $1.75; 500 grams $2.75. S e l e n i z e d : 100 grams $2.40; 250 grams $4.90; 500 grams $7.90. Ask your dealer or write

HENGAR COMPANY 6825 G r e e n w a y Ave. , P h i l a d e l p h i a , P a . 19142 Phone (215) 724-0800 · A division of Henry TROEMNER, Inc.

Circle No. 17 on Readers' Service Card

ΗENGAR

Portable, Plug-In High-Low Temperature

Cabinet For Labs! For cryobiology, pharmaceutical, industrial, and all research applications, the new Reliatemp, with a range from —100°F to +350°F with ±¥2° push button control. Operates off any 115 V outlet for just 2f per hour. 14" χ 10" χ 10" test area with optional shelves, viewing ports, etc. Refrigeration system is hermetically sealed and maintenance-free. Ideal for modern research applications. Write today for complete data.

A Division of Tenney Engineering, Inc. 1090 Springfield Rd., Union, New Jersey

Circle No. 134 on Readers' Service Card

Relialab VOL. 36, NO. 10, SEPTEMBER 1964 · 1 5 A