V O L U M E 26, N O . 3, M A R C H 1 9 5 4 done a t the University of Texas, Dcpartment of Chemistry, under the direction of Len% F. Hatch. LITERATURE CITEI) (1)
(2)
(3) (4j
(5)
(6) (7)
(8) (9)
Forch, Knudsen, and Sarensen, K u l . L h a s k e Iyide/iskab. Sclskub. Skrifte?, .Vaturvidenskab math. dfdel., 12, No. 1. 151 (1902). Glasstone, Samuel, “Textbook of Physical Cheiiiistry,” 2nd ed., New York, D. Van Nostrand Co., 1946. Hindman, J. C., and .Inderson, L. J., and Moberg, E. G., J . Marine Research, 8,No.1,30-5 (1949). Kolthoff, I. M,, and Furman, N. H., “Potentioinetric Titrations.” 2nd ed., New York, John Wiley & Sons, 1931. Kolthoff, I. &I., and Laitinen, H. A., “pH and Electi.otitratiotis,” 2nd ed., New York, John Wiley & Sons, 1941. Kolthoff, I. M., and Sandell, E. B., “Textbook of Quantitative Inorganic Analysis,” rev. ed., New E’ork, Macmillan Co., 1943. Snedecor, G. IT.,“Statistical Mcthods,” Amcs, Iowa, Iowa State College Press. 1946. Sverdrup, H. V., Johnson, M, IT., and Fleining, R. H., “The Oceans,” p. 51 and references contained therein. Keu. York, Prentice Hall, Inc., 1942. IVoods Hole Oceanographic Instit,ution, Xoods Hole, “Deteril~inationof Chlorinity by Knudsen Method,” M a s . , 1946.
C o s ~ r R i s r i i o sNo. 28 froin the Dcpartment of Oceanography, Texas A . and M. Colley?.
Capillary Specimens for X-Ray Diffraction Powder Analysis. F. \Ill,itthc\\ . F, (‘entral Research Laboratory, Canadian Indu\trw, 1,td , llcllasterville, Quehee, Canada. T H E mounting
619 free time and stored ready for uiie when :L specimen is to be mounted. Suitable glass or quartz capillaries can be purchased ( 5 ) but are readily drawn from Pyrex 707 (Corning Glass \Torks), a special formulation of glass which is less absorbing t,o x-rays than standard borosilicate or soft, glass. ii 15-mm., thin-walled glass tube has been found a coiivenient stock from which to drciIv capillaries \Yhirh should be 0.025 inch in outside diameter (measured with a S o . 22 B&S wire gage) 311d with a all t,hin enough to crush b e t m e n the fingers. Plaslir capillaries may be made from polystyrene or cellulose acetate h y a technique described by Beu and Classen ( 2 ) . To mount a q)ecinieii, a glass capillary wit11 tanipcd plug is inserted in the holc in the policeman and vacuum is :tpplied. A s the end of the c:ipill:try is placed near the powdered specimen, it is readily drawl into the capillary and is caught on the cotton plug. The tube niny be sealed in a fine flame if efflorescence, deliquescence, or rract,ion with the atmosphere is a difficulty. In one lsborator,v ( 1 ) it has been found more convenient to loave the wiqi oil the capillary and turn it end for end catching the cotton with the capillary in the hole in the policeman. When the specimen is in pl:rce, the cotton may be removed. The whole procedure c:m rentlily be carried out in a dry-box fitted with rubber gloves. Thrcc stages in thc prcparntioii of a sl)ccBimcn nre shown in thc rlraiving. LITERATURE CITED
Sational Researrh Counc,ii. O i i t : w i o , (’xnnda, priwtc communication. 13eu, K. E., and Classen, H. H.. Rei,. S c i . I / r s t ? . , 19, I T ! ) (1948). Gibson, G., and Bicek, E. .J., ANAL.CHEM..20, S84 (1948) (inisspelled Gihons in original article). Hagelston, P. J.. Dunn, H. W., Re,. Sci. In.str., 20, 873 (1049). Thetmal Ryndicntc, J . Sci. Instr., 28,289 (1951).
(1) Bai.iics, W. II.,
(2) (3)
(4, (5)
of x-ray diffraction powder specimens in glass or
7 plastic capillaries has advantages in that the specimen ip en-
cloxtl and no organic solvent or binder is rcquired. The qpecimen i z t h w straight and mounts readily on the chuck 01 d d l e wed in nioqt American designs of powder cameras. The di.advantage remains that the capillaries :ire difficult to prepare ant1 fill. Methods of doing this are described b y H,agelston and Duiin ( 4 ) :ind by Gibqon and Bicek ( 3 ) .
Apparatus for Fractional Sublimation a t Normal or Reduced Pressures. Kerner Hausmann, Rockefeller Institute for Xedical Research, S e w York 21, K,Y. Riiber described a veisatile, vertical vacuum b u b h i m I-vtor1900, consisting of a vaporizer and condenser connected by a
ground-glass joint [Ber.,33, 1655 (19Oo)l. To prevent ~ublimate from falling back he interposed an asbestos plate abovc the sublimand. The apparatus was heated in an sir bath. This subliniator is extremely ~ i m p l cto Get up, yet very cffectivc’. The apparatus described here consists of the same basic p:trts, except for the asbestos plate, which is replaced by a coarse eintercd-glass plate and a different type of heater. The di:tgrani qhon c the Fell known electrically heated micro
COTTUN PLUG
Thermometer
I (/--
Ti7kPk-D COTTON PLUG
Vacuum
-Sublimate
A tevliniquc which greatly simplified the filling of capillaries has been in u w in this laboratory for home years, although originality for thr method is not claimed.
Sintered
.4rubber polireman as used in analytical chemistry is put on a glass tube 6 inches long, and the rubber tip is cut off to leave a rubber cap on the tube. Through this cap a hole is made with a coarse needle, and into it the capillary is inserted. Suction is applied to the glass tube from a vacuum line with a bypass stopcock with which the vacuum can be readily adjusted. If an opening is made in the glass tube which may be readily closed with the index finger, very effective control of the vacuum is possible. -4cotton plug is made by rolling a tail on a wisp of absorbent cotton between the thumb and forefinger. The tail of the wisp may then be readily drawn into the capillary by full vacuum The vacuum is released and the wisp cut with sharp scissors. The cotton may then he lightly tamped to a plug with solid glass pokers inw-ted from either end. Capillaries can be prepared in
-
Hot
stage
+
Prn
