NOTES
Aug., 1950
3799
Experimental The data obtained included only two values which The sucrose was Standard Sample 17 prepared by the deviated as much as this from what seemed to be National Bureau of Standards.' This was received in a the best curve passed through these data and those highly purified condition and was used without further of Parks, Huffman and Barmore in the neighbor- treatment. Distilled water was used as the solvent. ing temperature region. Check measurements of The apparatus and operating techniques have been dethe heat capacity of water over this same tempera- scribed.' The apparatus was a twin Joule solution calorimeter holding about a liter of water in each side and having ture region gave values which agreed with those sensitivity limits of about * 0.02 cal on the basis of the accepted by Dorsey' within these limits. sensitivity limits of the 25 junction thermel-galvanometer In an earlier series of measurements on a combination. The values obtained for the heat of solution of sucrose in different sample of sucrose values were obtained water a t 25" are tabulated below. The heat of solution at which scattered widely. I n making these earlier infinite dilution was evaluated from the relation measurements the sucrose had been exposed to Bi - Hi = Q/n2 - 55.51Ll/m LI temperatures near 90' for more than two weeks by the time the final measurements were made. where ii," - Hi is the heat of solution at infinite dilution, By this time the value of the heat capacity of Q/np is the heat absorbed per mole of sugose dissolved, m sucrose a t 20' had increased to a value about 15% is the molality of the final solution and L1 and Lz are the higher than the values obtained earlier or those relative partial molal heat contents of tke water and sucrose reported by Parks, Huffman and Barmore. in solution. The values of LI and L2 at the indicated When the sample container was opened i t was molalities were obtained from the empirical expressions found that the sucrose had caramelized to a solid given by Gucker, Pickard and Planck? Concn. of Heat brown mass. Sucrose final s o h absorbed HZ - H Z I t is of interest that the sucrose caramelized dissolved, mole molality ' cal./mole '1 cal./mole' a t temperatures well below the decomposition 0.008214 0.008237 1453 1452 value of 186' given in the handbook.8 .008555 .008579 1462 1461 When the measurements reported here were .007921 .007943 1448 1447 made only three determinations were carried out .008103 .008126 1468 1467 above 45' and these in the shortest possible .007671 .007692 1447 1446 time. After completion of the measurements a Mean value 1455 * 5 check determination of the heat capacity a t ( 5 ) Circular C 440, U. S. Department of Commerce, Xational room temperature gave a value in agreement Bureau of Standards, page 392. with the other values within the estimated un(6) Fineman and Wallace, THISJOURNAL, 70, 4165 (1948). certainty of the measurements. When the sample (7) Gucker, Pickard and Planck, ibid , 61, 469 (1939). container was opened i t was found that the sucrose M . W. KELLOGG Co. was still powdery and white and that there was no JERSEY CITY3, 9.J . RECEIVED FEBRUARY 11, 1950 visible evidence of decomposition.
-
( 7 ) N. E. Dorseg. "Properties of Ordinary Water Substance," Reinhold Publishing Corp.. New York, N. Y., p. 613 and 616. (8) "Handbook of Chemistry and Physics," 29th edition, Chemical Rubber Publishing Co., p. 1019; see, however, Circular C440 (loc. cif.) p. 398.
The Preparation and Structure of Lanthanum Cobaltic Oxide
M . W. KELLOGG Co. CITY3, N. J.
The existence of the perowskite-like compound of approximate composition BaFeOz.e33 suggests that i t might be possible to prepare a similar compound of cobalt. Since no such compound was found, the substitution of lanthanum for barium was tried. Naray-Szabo4 has prepared LaMnOl and LaFeOs by heating oxides of manganese and iron with lanthanum oxide and has shown that the products were of the perowskite type. Hedvallls however, reported that no compounds were formed when lanthanum and cobaltous oxides were heated together a t 1100 to 1300'.
JERSEY
RECEIVED FEBRUARY 1 1 , 1950
The Heat of Solution of Sucrose in Water a t 2501 BY HOWARD H I G B I E 2 AND GEBHARD sTEGEMAN3
Measurements of the quantities needed for a thermal description of the system sucrose-water are being made in this L a b ~ r a t o r y . ~This paper presents measurements of the heat of solution of sucrose in water a t 25' and an evaluation of the heat of solution a t infinite dilution a t this ternperature. ( 1 ) This work was supported by a grant to the University of Pittsburgh from The Sugar Research Foundation Inc. and is a portion of the dissertation presented by Howard Higbie to tbe Graduate School of the University of Pittsburgh in partial fulfillment of the requirements for the degree of Doctor .of Philosophy. (2) The M. W. Kellogg Co., Jersey City 3, N. J. (3) Deceased September 5, 1949. (4) Anderson, Higbie. and Stegeman, THIS J O U R N A L , 72, 3798 (I
!,no),
BY FREDASKHAM,' I.
FANKUClIEN ASD
ROLAND ~
A
R
D
Experimental Intimate mixtures of the hexahydrates of lanthanum and cobaltous nitrates ___ _ were heated in a tube furnace in a stream (1) Abstracted from a thesis submitted to the Graduate School of the Polytechnic Institute of Brooklyn by Fred Askham in partial fulfillment of the Master of Science degree 1950. (2) Department of Chemistry, University of Connecticut, Storrs, Connecticut, (3) M. Erchak, Jr., I. Fankucheu aud K. Ward, TEIS JOURNAL, 68, 2085 (1946). (4) I. Naray-Szabo, Naturwissenschaffen,81, 466 (1943). ( 5 ) J. A. IIedvall, Z. anorp. allgem. Chem., 98, 313 (1915).
~
NOTES
3800
of air. The temperature was raised gradually (to prevent spattering of the melt) to a fixed temperature a t which it was held constant for twelve to twenty-four hours. The products were periodically removed from the furnace, ground in a mortar and again heated. Products obtained over the range 150 t o 1020' were examined by X-ray analysis and the diffraction patterns of several unidentified phases were obtained. From the mixture in which the ratio La/Co = 1, an essentially 5omogeneous product It appeared to be was obtained between 800 and 970 contaminated by a small amount of lanthanum oxide. Chemical analysis showed that the valence of cobalt in this product is 3; Subsequent study of the diffraction patterns of the 700 roducts from mixtures in which the ratio La/Co range! from 0.5 to 3, showed the presence of the same phase strongly contaminated with other phases. From these results it is reasonable to conclude that the composition of the persistent phase is LaCoOs. Further justification for this conclusion was obtained by the determination of the structure. The diffraction pattern (given in Table I) resembled that of a perowskite structure except that many lines appeared as doublets and a few as triplets. This was taken as a n indication that the structure was slightly distorted from the cubic. A tentative value (3.82 .&.) was obtained for the pseudo-cubic unit cell dimension by assuming that the innermost reflection was due to the 100 plane. Upon this basis, the other lines of the pattern were indexed. It was found that reflections corresponding to the 100, 200,
.
TABLE I X-RAYDIFFRACTION PATTERN OF Lac003 I = Intensity; VS = Very strong; S = Strong; M = Medium; W = Weak; VW = Very weak; VVW = Extremely weak I
d
3.82 2 681 2.213 2.178
M
vs
1
VS M W S
vvw vvw
1 701 1 568
S M M
M VVW
M M
vw vw W VW VVW
vvw
1.027 1.021
ha
+ + kl
1 2
3 4
5 6
8 9 10
11 12 13
hf '
w
14
W
16
vw
18
w
vw vur vw vw vw
W W
12
Vol. 72
300 and 400 planes were all single lines while those due t o such planes as 110, 111, 210, 221, etc., were doublets or triplets. This points to a rhombohedral unit cell the interplanar spacings for which can be calculated from the equation 1 (hz4-ka 1') sinz a+ 2(hk hl kl)(cos2 a: COS LY) aZ(l 3 COS%Y 2 COS~CU) where a: is the interaxial angle. The value for (Y was found t o be 90'42'. The obtuse angle was chosen on the basis of the relative intensities of pairs of reflections when compared with the number of equivalent reflections that could be obtained from a set of planes. Table I1 gives the computed and observed values of d* (d: = h/d = 2 sin e). Since excellent agreement was obtained, the unit cell dimension was recalculated using the equation given above. It was found t o be 3.82 * 0.01 A. TABLE I1 A COMPARISON O F VALUES O F d*obs. A S D d*caicd.
s=
+
-
+ + +
-
Plane
d* obs.
d* calcd.
100 110 -110 111 111 200 210 210 2ii,2i1 211 220 220 300 310 310 8ii,3ii 311 222 222 320 320 321,321 32i 321 400 330, 211 330, 411 320 -420 332,332 332 422 422
0.403 ,566 .574 ,695 ,707 ,806
0.403 .567 ,574 ,695 ,707 ,806 ,897 ,906 .983 .997 1.133 1.147 1.209 1.270 1.279 1.334 1.347 1.391 1.413 1.445 1,461 1.501 1.510 1.522 1.612 1.701 1.720 1.794 1.811 1.884 1.912 1.962 1,970
.896 .905 ,982 ,997 1.133 1,147 1.208 1.270 1.279 1.335 1.347 1.390 1.412 1.442 1.460 1.500 1.508 1.520 1.611 1.700 1.719 1.795 1.812 1.883 1.913 1.959 1,970
The density of LaCoOa was found to be 7.2 g./c.cm. which corresponds to one formula weight per unit cell. RECEIVED FEBRUARY 16, 1950
7-Isopropylpodocarpinol
20
BY MANUELM. BAKZER,MARILYNK~RNOWSXY AND W. G. BYWATER
22
Campbell and Toddf have shown that 6-hydroxydehydroabietic acid (I) differs from
24
(1) Campbell and Todd, THISJOURNAL, 64, 928 (1942).
