1338
ANALYTICAL CHEMISTRY
Table I.
Reproducibility D a t a Using Constant-Volume Capillary Pipet
8P.mg1e n-HeDtane "-Heptane %Xylene m-Xylene
Date 1949
5/18 5/19 5/20 5/31
No. of Average Standard Probable Datu. Peak Helght Deviation Emor 7 254.8 0.89 0.60 14 7 10
261.7 1764.0 1787.4
1.19 9.04 9.67
0.83 6.46 0.48
original ginding down, and this is followeu uy rreacmenx with No. 0 paper. A final polish is given to the ground surfaces with No. 00 emery paper. In sampling with the capillar pipet, i t is essential that the order to fill the pipet, the tip capillary he thoroughly clean. is merely touched to the surface of the liquid sample. The sample is drawn into the pipet by capillary setion. A Corning Type F sintered-glass disk covered with mercury is used to introduce the sample into the instrument. Enough mercury must cover the fritted plate to ensure complete immersion of the pipet when the tip contacts the surface of the fritted plate. Reduced pressure beyond the fritted plate then ulls the sample from the pipet and mercury enters the top of t i e pipet and rephees the sample in the capillary. Extreme care must be exercised in introducing samples with the pipet to make direct contact with t,he fritted plate, avoiding any scraping or scratching of the
2:
37.
fritted plate surface, a8 sm capillary. These pipets have been us- a a ~ ~ c ~ 111 n crn e y~ eiauurarones for analyzing liquids as high aa Ctg hydrocarbons with the inlet system at room temperature. Typical reproducibility data are shown in Table I. .klvantagrs of this procedure are that coustaut ilvpuratc "01!mi+( re introduced for rxlibrations nnd analyses without LL me&+ iirerncui r e q u i d , and no smsitiviry calculations are required, b e w u 3 e comput*rionu are madc directly from peak heights.
sampi; the whole pipet is gaced in tube A: and the tube is connected to the instfument: Dry ice is packed around the tube while it is evacuated. Then the heater is placed around the tube and gradually heated until all the sample is vaporized from the pipet. LITERATURE CITED
( 1 ) Friedel. A. E.. Sharkey, A. G.. and Hurnbert. C. R., ANAL. C E E M . . ~1572-3 ~. (1949). (2) Taylor. R. C . . and Young. W. S., IND. ENQ.Ca~ar..ANAL.Eo.. 17, 811 (1945).
RECEWED January 18. 1950.
Phenylacetic Ac:id (a-Toluic Acid)
Contributed by DONALD G. GARB)iR AND WALTER C. MCCRONE .irmour Research Foundation. Illinois Inrstitute of Technology, Chicago 16, 111.
0 C>-CH&" O 'H Struotural Formula for Phenylacetic Acid Phenylaoetic wid is soluble in most common solvents. Crystals for x-ray diffraction were gown from water solution and those for optical studies by ncrystallization on a microscope slide from Cargille refractive index liquids. CRYSTAL MORPHOLOQY
X-RAYDIFFRACTION DATA gP:cLGrouP; (1). , , . , -L e 1 1 uimensious. a = 14.m A.: b = 4.98A,: c = 1U.17 A, a = 14.2 A .; b = 4.90A.; c = 10.0A. (1). Formula Weight per Cell. 4. Formula. Weight. 136.14. Density. 1.228; 1.262 (x-ray),
c:,
^ ^
d 14.38 7.08 6.32 5.91 5.05 4.74 4.49 4.33 4.19 4.08 3.81 3.06 3.52 3.34
1.00 Very weak Very weak Very weak
3.16 3.02 2.89 2.79 2.69 2.55 2.48
0.11 0.18 0.53 0.77 Ver weak 8.22 0.14 Very weak 0.59 0.10
0.16 0.13
Very weak Very weak 0.15
Very weak Very weak Very weak Very weak Very weak Very weak Very weak Very weak Very weak Very weak
%A
2.20 2.w 1.9Y 1.87 1.78 1.01
npnrrr. P, .~ Refractirr
S = 1.569
UWSX~BLI
A,;
LO
-.I.
BL
= i.00~
r V.WI;
0.002; 7 = 1.671 f 0.005. Optic Axial Angles (5893 A,; 25' C.). 2V = 39'; 2E = 67". Dmpersion. v > r siignc. '' ' ' Optic Axial Plane. 010. Sign of Double Re fraction. Positive. Acute Biseetrix. Y . Extinction. 9, A c = 5' in obtuse 8. Molecular Refract; ( R ) (5893 A,; 25' C.). q& = 1.599; R (calcd.) 35.7; 6 (Obpd.).= 37.8. , . .. FUSION DATA. Phenyiaceclc acia melt4 mthout aecomposltlon a t 76" C. It crystallizes without seeding forming flattened rods lying on 100 and some crystals elongate6 parallel to c lying on 010. The crystal front in a mixed fusion nsuall has illdefined profile angles due to solubility. However, B Canaia halsrtm mixed f
I
-
9 I
., .
.
1339
V O L U M E 22, NO. 10, O C T O B E R 1 9 5 0 fusion will permit measurement of the p angle and extinction before the crystals become too rounded. Some of the crystals from fusion show a slightly inclined Bx. figure with 2V = 39”, u > T , (+). No evidence of polymorphism was observed. C
=
I
which may be employed by those wishing to use the text for students in the latter part of the freshmail year. The book is highly recommended for the serious consideration of teachers of analytical chemistry. JACOB KLEINBERQ
C 102/1
a-
Philadelphia Section Meeting The Chrmical Education Committee of the Philadelphia Section, AMERICAN CHEMICAL SOCIETY, will present a continuation course on “Advances in Chemical Analysis,” a t the Philadtblphia College of Pharmacy and Science on Tuesday evenings. Information is available from R. E. Vener, Drexel Institute of Technology, Philadelphia 4, Pa.
Figure 2. Orthographic Projection of Typical Crystal of Phenylacetic Acid
17 Ion Exchange in Analysis. W. RIBMAN111, Rutgprs University October 24 Countercurrent Distribution. L. C. CRAIG, Rockefeller Institute for Medical Research October 31 Isotope and Radiaactive Tracer Techniques. G. G. MANOV, Atomic Energy Commission November 7 Determination of Organic Functional Groups by Chemical Means. S. SIGGIA, General Aniline and Film Corp. November 14 Flame Photometry. T. E. WEICHSELBAIJM. Washington University, St. Louis November 21 Polarography of Organic Compounds. P. J. ELVING, Pennsylvania State College November 28 X-Ray Absorption. H. A. LIEBHAFSKY, General Electric Co. December 5 Chromatographic Separations. A. L. LEROSEN, Louisiana State University December 12 Statistical Evaluation of Analytical Data. W. J. YOUDEN, National Bureau of Standards October
It is a pleasure to acknowledge the help of Ann Humphrey8 in determining the powder x-ray diffraction spacings and intensities. LITERATURE CITED
(1) Patterson, A. L.,Phil. Mug., 3, 1252 (1927). CONTRIBUTION. of orystallographic data for this section should be sent to Walter C. hlc’Jrone, Analytical Section, Armour Research Foundation of Illinois Institute of Technology, Chicago 16, Ill.
+
Semimicro Qualitative Analysis. William C . Oelke. ix 377 pages. D. C. Heath and Co., 285 Columbus Ave., Boston 16, Mass.,1950. Price, $3.75. In the reviewer’s opinion, this book will go a long way toward satisfying the increasing desire of teachers of qualitative analysis for a text which assigns to the subject its appropriate importance in the chemistry curriculum. Oelke’s attempt to emphasize the laws of chemical equilibrium as the logical basis for the analytical procedures utilized is highly successful; the correlation between theory and practice leaves little to be desired. The discussion of the theory of electrolytic solutions and their equilibria is in modern terms and will serve as an excellent background fQr students who go on to advanced courses in chemistry. The section on acids and bases is particularly well written. The descriptive material dealing with the analytical scheme is clear and concise. In addition to the common inorganic tests for the various ions, tests with organic drop reagents are frequently given. An intelligent preliminary discussion prepares the student for the use of these reagents. An important factor contributing to the value of the descriptive portion of the text is the utilization of current knowledge and concepts concerning the chemical nature of the various ions and precipitates encountered in the analytical scheme. The use of appropriate literature references to document the material and to serve as stimuli to the more curious students is warmly commended. Oelke has carefully selected the wide variety of exercises and problems found a t the end of each chapter; they well serve to illustrate and illuminate the principles of both the theory and practice of qualitative analysis. Although the book is primarily designed for a sophomore course, there are abbreviated cation and anion analytical schemes
This continuation course conflicts with the meetings plqined by the Analytical and -Microchemical Group for November and December as announced here last month. The meetings will be held at the Harrison Laboratory of Chemistry, University of Pennsylvania, 34th and Spruce St., Philadelphia. Chromatography of Colorless Organic Compounds. JOHN W. SEASE,Wesleyan University. November 2 Determination of Molecular Weight. ROBERTE. KITSON, Polychemicals Department, E, I. du Pont de Nemours & Co., Inc. December 7
Indiana Symposium on Analytical Chemistry The Indiana Section of the AMERICAN CHEMICAL SOCIETYhas announced its fourth Symposium on Analytical Chemistry, to be held a t the Indiana World War Memorial, Indianapolis, November 4 from 8 A.M. to 5 P.M. The program includes: Organic Analytical Reagents. FRANK WELCHER. Radioactive Assay. T. GLEASON AND D. L. TABERN.Anhydrous TiGEOFFREY tration. JOHNRIDDICK. Paper Chromatography. WALTER WINSTON. Analytical Spectroscopy. RICHARD C. LORD.
Optical Society of America. Cleveland, Ohio, October 26 t o 28
Fourth Symposium on Analytical Chemistry. Louisiana State University, Baton Rouge, La., January 29 t o February 1, 1951 Pittsburgh Conference on Analytical Chemistry and Applied Spectroscopy. William Ponn Hotel, Pittsburgh, Pa., March 5 to 7, 1951 Fourth Annual Summer Symposium. Washington, D. C., June 14 to 16. 1951
I
