increase in absorbance in all blank determinations. The method described was used for determinations of hydrogen content in pure water systems adjusted to contain between 5 and 50 cc. of hydrogen per kilogram of water on a daily routine basis. Standard deviation from the mean of multide determinations on the same system was *50j,. No comparisons were made to other methods for hydrogen dissolved in water.
ACKNOWLEDGMENT
The authors are indebted to F. D. Bell of this laboratory for analytical assistance and to the U. S. Atomic Energy Commission and the Westinghouse Electric Corp. for permission to publish this work. LITERATURE CITED
(1) Easor, J. E., Jr.,
Harves, T. O., Conkhn, D. B., Office of Technical
Services, Dept. of Commerce, Bettis Tech. Rev. WAPD-BT-7,146 (1958). (2) “Handbook of Chemistry and Physics,” 39th ed., p. 1606, Chemical Rubber Publishing Co., Cleveland,Ohio, 1957-58. (3) StaNberg, K., Isoniemi, M., Suomen Xemistilehti 27B,86 (1954). RICHARD H. ROBINSON DWIGHT B. CONKLIN Atomic Power Division Westinghouse Electric Corp. Pittsburgh 30, Pa.
183.
Growth and Crystal Structure of Single Crysta Is of Pr(N03)3. 6H,O J. W. RICHARDSON, Q. W. CHOI,l F. VRLTN?, and J. M. HONIG2 Department of Chemistry, Purdue University, Lafayette, Ind.
I
of studies on the oxidation of nonstoichiometric praseodymia, it was necessary to obtain information on the properties of praseodymium nitrate. Because of lack of information on the growth and properties of this compound, a brief study was undertaken. N THE COURSE
Single crystals of the material were grown by dissolving high-purity Pr6011 in hydrochloric acid solution and evaporating the solution almost to dryness; the resulting chloride was treated with nitric acid and evaporated almost to dryness. To ensure complete elimination of chloride ion, this treatment was repeated three times on a steam bath. The residue was placed in a desiccator together with a 15% sodium hydroxide aqueous solution in another beaker. Because of the extreme hygroscopicity of praseodymium nitrate, this compound slowly dissolved in water withdrawn from the sodium hydroxide solution: the process was terminated as soon as complete solution of the nitrate .was achieved. A 40 to 45% aqueous sodium hydroxide solution was now substituted. As its vapor pressure was slightly less than that of the praseodymium nitrate solution, a slow transfer of water to the sodium hydroxide reservoir occurred. This resulted in a slow but steady growth of a single crystal of Pr(N03)s.6Hz0, with dimensions 2 x 1.5 X 0.5 cm. The crystal exhibited a marked spiral dislocation pattern on the top surface. This technique can be used whenever Present address, Department of Chemistry, Cornel1 University, Ithaca, N. Y. * Present address, M.I.T. Lincoln Laboratory, Lexington 73, Mass.
the substance to be crystallized is soluble in moderately volatile solvent and the solvents can be distilled in a similar manner, It has the following advantages: No special equipment is required; moderate temperature fluctuations can be tolerated because the aqueous vapor pressures of the praseodymium nitrate and sodium hydroxide solutions change in the same direction with temperature changes; and the vapor pressure of the desiccating solution increases as evaporation from the crystallizing system takes place, so that the rate of evaporation of water vapor is automatically reduced as the solution approaches the stage of nucleation. This makes it possible to grow a single crystal at a time. The latter effect can be enhanced by utilizing a small amount of desiccant solution relative to crystallizing solution. The rate of distillation can be adjusted easily by varying the surface area of the vessel containing the desiccant. Another set of single crystals was accidentally grown during attempts to produce the anhydrous material in large quantities, in the course of which the vacuum line was destroyed. Hydration then took place and the single crystals thus obtained measured 1 x 0.5 X 0.1 cm. One of these was cut up into small sections and a fragment was sealed in a thin-walled borosilicate glass capillary for x-ray diffraction studies. The crystal was mounted on a Weissenberg camera; x-ray scattering from nickel-filtered CuKa radiation was recorded photographically. Because of the reported thermal instability, air
was blown over the capillary during measurements. A serious difficulty arose in the process of aligning the crystal axis with the rotation axis. During the preliminary x-ray measurements, the crystal apparently changed from an initial to some other structure. I n the course of further alignment, the crystal returned to its initial state, although to a somewhat different orientation within the capillary. Considerable difficulty was encountered in preserving the specimen through the alignment stage. However, after the process was completed, 0-level Reissenberg (hkO) data were recorded. Following this, the crystal became disoriented, and another alignment process had to be attempted, with the same attendant difficulties as before. After a second alignment, a complete rotation photograph and a second set of Weissenberg 0-level photographs were again obtained. Thereupon , the crystal totally disintegrated. An analysis of the rotation photograph and the first set of 0-level Weissenberg data showed that the lattice is monoclinic and assumed primitive; the cell constants are: = 8.64
* 0.05 A.
0.05 A. co = 6.78 112 zt
-f
bo = 11.75 zt 0.05 A. 7 =
3O.
Calculated density for two formula units per unit cell, 2.42 grams per cc. Observed density, 2.48 grams per cc. by displacement of ethyl acetate. The indicated uncertainties are rough estimates, Indexing of the Weissenberg data revealed that all hkO reflections are in VOL. 31, NO. 9, SEPTEMBER I959
1599
general present, and the lattice constants were computed, assuming that the lattice is primitive and that no glide pkanw occur. If either or both of these conditions fail fa hold (as would be revealed only from Akl data), one or mow of the lattice constant3 would have to be doubled, with a eonsequent increase in the number of formula mi& p e p unit! cell. ImdGEitoy &o obtain further data prevented identification of the space group. The external shape of the small single crystal also ws9 nob sufficiently g o d
to permit identification of the point symmetry group, except t o identify the existence of a twofold axis of rotation. The second set of O-level diagrams was similar to the first, except for the occurrence of four additional, moderately weak reflections. These indicate a reduction in lattice a p e b y to #e triclinic system and require doubling of the a &. This is the result of distortions or defects suffered by the crystal during disorientation. In all probability, a motion or loss of groups of low diffracting power is involved, such as the
Infrared Analysis of a Mixture of 1,4Dihydroxy C4's
CS-9 1
H. 1. SPELL, The Dow Chemical Co., Freeport, Tex.
1
Slit Component Name Formula
No.
-I1
___
1.4-Wyrce-2-
-I-
_
'1,4-cis-&&ene-
2-diol
-
%
Av
Pfr.
~___
_
IC4Ho02
,---
I
-I
E
~ O N T ~ U B U T I ~oN f S my&dbgraphic
data for t b section &odd b aent to Walter C. M c C F O ~501 ~ , E& a d St., Chicago 16, FD.
Analysis of Toluene-Butylbenzene Mixtures R. J.
JAKOBSEN and C. D. SMITH Battelte Memodal Institute, Columbus, Ohio
cs-93
mm
Alit Component
100
0.1 _ 100 0.1
Inrtrumenf: Perkh-Elmer Model 2 1, NaCf prkar SompA Phose: Solution in corbon dhvWlde
Cdf Windows: NoCl Absorbance Meammment:
Cell Windows: NaCl Absorbance Meawrement:
Base line-
Inverse m a t r i x x Graphical-
Rebtiw Abrarbonce+Anafytkol ComponenilX 8.8
Point-L Successive opprox.--
1
2
3
Calculation:
Matrix:
7~ 0.412 0.017 0.023
9.67~ 0.394 0.467 0.159
9 * 44p 0.073 0.169 0.572
Material Purify: Reference compounds 99+% pure Commentrr All sample preparation should b e done In a dry atmosphere. ReluHve abrorbunces are given as the slope of the Beer's law concentration curves used expressed In terms of absorbance per 100% of cansthutvent.
Analysis of Benzene-Mesitylene Mixtures
Benzene
1
1 I
No.!
Mesitylene
CeHg
%
10-100
CsHl2
0-100
%
Pfr.
AV
11.97
l;i25
Length mm
ANALYTICAL CHEMISTRY
9.48
2.175 7.050
Reference compounds 99 +% pure
e Reiotive abroibances are given as the slope of the Beer's l a w concentration curves used expressed in terms of absorbance per 100% of constituent.
I
0.227 40 0.052
Base l i n e - L
Point--
Inverse matrix& Successive opprox.__ GI a phicaI
Relofive Absorbances"-Analytical Matrix: Componenfl?,
0.630 40 0.113 0.052
Theae data represent standard publication and submission is open to any one in accordance with regulations of ANALYTICAL CHEMISTFLY.The Coblentz Society is acting only as an aid to the journal.
1600
Material Purify:
mg/ml
fmm)
fO.l
2
Cdculofion:
AX or
I 1 1 1
1
Concn.
B.L.
15.25
Successive appro%-
9.26 15.250 0.800
Componentlk
Slit X or v
14.25-
Pohrt-
Rektive Abrorbancer'-Analytica~ Motru:
Cell Windows: NaCl Absorbance Measurement:
Accuracy
__ f O . 1 14.83
Inverse m o t r i x X Gruphical-
CS-92
Bottdle Memorlal Inrtltute, Columbus, Ohlo
Range
Bore l i n e - L
Inrfrumenf: Perkin-Elmer Model 2 1, NaCl prism Sample Phase: Solution In carbon disulfide
R. J. JAKOBSEN ond C. D. SMITH
Component Name Formulo
Concn.
___
Insfrumant: Perkin-Elmer Model I 12, NaCl prism Sample Pham: solution in ocetme
Cdculaficn:
2
RESEARCH supported in part by the United States Air Force through the Air Force Office of Scientific Reeea~chof the Air Research and Development Command under contract AF 18(603)-45. Reprcia permitted duction in whde or in for any purpose of the avernment.
Concn.
8 . 8 7 0.160 0.019 ~ ~ - _ _ _ _ 0-100 413.0 9 . 6 7 0.260 0.028 f2.O
0-100
C
