V O L U M E 21, NO.
4, A P R I L 1 9 4 9
531 i.les on a vacuum column. Tho stopcock in the distillate take-off line functions only to close the line against pressure during this operation. The vapor temporature is measured with a single- or multiplejunctian thermocouple in a well, looated directly in the path of the ascending vapors and close to the point of takeoff. The lower part of the head requires some insulation. The omission of a vacuum jacket greatly simplifies oonstruction; an enclosure of cellular pipe insulation is adequate for most purposes. The reflux ratio obtained with the head was considered to be equal to ratio of time off to time on of the timer. Because the valves seated almost perfeetly, with no leakage over long periods on all thc heads built, i t was felt, that this was a justifiable a s s u m p tion for the reflux ratios of 50 t.a 2 being used and the accuracy required. Heads of this type have been operated continuously on a 2 4 hour basis for over a year without leakage or other indications of wear or deterioration. LITERATURE C I T E D
(1) Bertleson,
J. D.. Conrad. A. L., and Far, P. S.,IND.ENG.CHEM..
ANAL.ED., 18,724 (1946).
(6) Lloyd, L. E., sndHornbaoher. II. G., Ibid., 19, 120 (194i). (7) Palkin, S., and Hall, S.A,. Ibid., 14,901 (1942).
(8) Podbielniak, W. J., Padbielniak Centrifugal Super-Coiltractor Co.. Circ. 22 (November 1942). (9) Snyder. J. C . , and Steubor. W..1x11.ENO.C H E ~ ANAL. ., En..16, 454 (1944).
Figure 1. Vacuum Column Head
R ~ C E I V ESatember D 1 1 , 194fi.
17. o-Aminophenol .
Good crystals of o-aminophenol can be prepared by sublimation. When sublimed macroscopically, the crystals are large enough and well enough formed to be used for single crystal x-ray measurements. When sublimed from one microscope slide to another they can be used for optical orystallogrslphy. Figure la, shows the characteristic preparation of o-aminophenal prepared by sublimation from one slide to another. Figure l b . shows a characteristic fusion pieparation of o-aminophenol. Figure 2
Figure 2. Orthographic Projection of Typioal Crystal of o-Aminophenol
s h a m orthographic projection drilwings of a typical crystal of o-aminophenol. There was no evidence of polymorphism during crystallization from solutions or from the melt. b
Figure 1. o-Aminophenol a. Crystals obtained by sublimation from slide to cover glass (1. Fusion prepsretioo shoving oharactsristic ahrinkage rraeha
C R Y ~ TM~RPHOLOQY ~L (determined by W. C. McCrone). Crystal System. Orthorhombic. Farm and Habit. Tablets lying on the brachypinaooid I O l O l showing the hipyramid forms 1111). 11211, and (2121 and the mncropinacoid I1001
ANALYTICAL CHEMISTRY
532 Axial Ratio. a : b : c = 0.367:1:0.398, Interfacial Angles (Polar). 012 A 012 =- 107" 20'; 011 A 01 = 139"-10'; 021 A 02T = 159" io'; 210 A 2 10: 1 5 7 ~ 3 2 ' ; lion, Tio = 136" 40'; 120 A i 2 0 = 103" 0'; io1 A io1 = 8 5 O 30'. X-RAY DIFFRACTION DATA(determined by J. F. Whitney and I. Corvin). Space Group. Pbca ( 1 ) ; PcaP ( 2 ) . Cell DiFensions. a = 7.85A.; b 19.74A.; c =, 7.25A. a = 7.26A.: b = 7.71d.:* c = 1 9 . 5 l A .,( l.) . a = 7.84A.: b = 7.28 d.; c =' 19.7 A. ( 2 ) . Formula Q7eightsper cell. 8. Formula Weight. 109.12. Density. 1.283 (buoyancy); 1.282 (x-ray); 1.328 ( 1 ) . Principal Linen d 10.04 5.88 5.13 4.95 4.69 4.12 3.92 3.86 3.64 3.41 3.25 3.13 3.06 2.94 2.82 2.73 2.65
I/Il 0.31 Very weak 0.03 0.02 1.00 0.14 Very weak Very weak 0.07 0.13 0.13 0.11 Very weak 0.13 0.07 0.08 0.11
d 2.60 2.57 2.52 2.46 2.43 2.37 2.33 2.24 2.20 2.18 2.13 2.07 2.01 1.96 1.95 1.89
0.09 0.10 0.05 Very weak Ver weak Verg weak Very weak 0.02 Very weak 0.03 Very weak 0.05 0.03 0.05 0.05
Very weak
OPTICAL PROPERTIES (determined by W. C. XcCrone). Refractive Indexes (5893a.; 250 C. ). CY = 1.618 * 0.002. B = 1.632 * 0.002. y = 1.T74 * 0.01. Optic Axial -4ngles (5893A.; 25" C.). 2v = 39". 21' = 67". Dispersion. r > v (very slight). Optic Axial Plane. 100. Sign of Double Refraction. Positive. h&te Bisectrix. b. Extinction. Parallel and symm:trical. Molecular Refraction ( R ) (5893.2.; 25' C.). = 1.671. R(ca1cd.) = 32.4. R(obsd.) = 31.8. FUSION DATA(determined by W, C. JIcCrone). Crystals of o-aminophenol sublime readily to give 1%-ell-formed crystals lying on the brachypinacoid { O l O ) . This view shows a 94.5" profile angle, Bz, figure with 2V = 39", (+), r > v and two indexes: CY = 1.618 and p = 1.632. Fusion gives a melt (173" C.) which crystallizes readily with little supercooling to give large areas of uniform orientation. All show the same principal view (lying on O l O ) , hence show the same optics as sublimed crystals described ahove.
+&
LITER4TURE CITED (1) Caspari, W. A., Phil J f a g . , 4, 1276 (1927).
(2) Kitaigorodski, A. I., Iznest. Aknd. S a u k S.S.S.R., Otdel. Khini. h'auk, 1948, 278.
M.I.T. Graduate Program in Analytical Chemistry Because the rapid growth in the application of instrumental methods to chemical analysis has necessitated major changes in the conventional program of graduate training in analytical chemistry, the hlassachusetts Institute of Technology is offering a completely revised and greatly expanded program of study leading to the degree of doctor of philosophy. The new curriculum is designed to prepare men for leadership in industrial work, research, and university teaching. The program provides a broad background in inorganic, physical, and organic chemistry and emphasizes both organic and inorganic aspects of analytical chemistry. Course work stresses principles and methods; thesis problems are designed to provide a varied research experience as well as specialization in a field of limited scope. Information and application forms for assistantships and fellowships may be secured from the head of the Department of Chemistry, Massachusetts Institute of Technology, Cambridge 39, Mass.
Crystal Structures. Ralph W . G . Wyclcoj. Seven chapters, cach separately paged. Section I. Interscience Publishrrs, Jnc., 215 Fourth Ave., Xew York, ?;. Y., 1948. Price, $8. This loose-leaf book in its dark blue binder is already one of the most familiar and easily recognized additions to many libraries. The reviewer in the past month has had a glimpse of at, 1eaqt twenty copies in industrial and university libraries and laboratories. Thus it is evident that this contribution has been eagerly aaaitrd and thankfully received. The author, one of the great pioneers in x-ray diffraction and crystal structure analysis, needs no introduction and his name on the binding is immediately a recommendation of authoritative excellence. In 1931, Kyckoff published his "Structure of Crystals," followed in 1934 by the "Supplement to the Structure of Crystals." In a sense this 1948 book is a new edition of the supplement, but actually it is entirely new, from the very first sentence to the last. .4riyone who has an interest in crystal st,ructureand in the growth of the logical science of crystal chemistry knows instantly the great value of this compilation. As Wyckoff clearly states, it would he necessary to go through the seven volumes of the Struktu/,bericht which covers the literature up to 1939 and then follow this by a year by year search in order to find any specific piece of information or any kind of generalization. This book, of which only the first of three sections has thus far appeared, states the results of all available determinations of atomic positions in crystals. This first section covers structures of the elempts, compounds RS, RX2, 'R,X,, R(hlX?),, and R,(hIXs),. Section I1 d l cover R,(MXd),, R,,(ILIXF)~, R,,MXpj hydrate?, silicates, and miscellaneous organic structures; while Section I11 will cover organometallic compounds, aliphatic compounds, aromatic compounds, and more complicated organic compounds. ill1 thwe sections \vi11 fit into the binder already supplied. These three sections are to be followed a t intervals by supplements covering new determinations as they are reported. In all cases the printing is by the vari-type method. Each chapter consists of a test, and a t the bottom of each page appears the numbering-for example, Chapter 111, text page 40. Each chapter next contains tables separately paged, then illustrations, and finally an exhaustive bibliography. These illustrations, which are designed to cover every separate type of structure, are done i n a masterly fashion and give as good an idea of thrw dimsnsions as it is possible to represent i n two dimt:nsions. One of the most striking features of Wyckoff's work is its uniformity. This is no compendium collected from the efforts of a group of assistants. There is evidence on every page that Wyckoff has himself examined every literature reference, weighed the evidence carefully, organized the information, and placed it in its proper relationship in the text. One has only to try to do a little of this to realize the hundreds of hours and the intensive concentration and the devotion to a subject and to a reading public which this kind of publication represents. There is no discussion of diffraction apparatus, techniques, or interpretation. Rather, this is a single-handed, unified encyclopedia. At the same time, the reviewer finds it an excellent test in any course concerned with advanced inorganic chemistry or crystal chemistry. So carefully is the manuscript prepared and so w-ell have the printing and proofreading been done that the
