The effectiveness of the density-composition curve as an analytical tool is sufficient to establish composition t o about 0.3 unit or better on the atomic per cent scale. IlEFERENCIiS (1) BILTZ,JY.,ASI) HoaoRsr, ( ; . : %. aiiory. allgern. C h r n i . 127, 1 (1923). LEE,W. B . : Proc. Roy. SOC.(London) A103, 487 (1923). (31 GRCBE,'2.)AN IEDT, 1 1 . : % . anorg. allgern. Chem. 194, 190 (1930). (4j ~ I n f E - R o T I m z TW., , A X U RAYXOR, G . I-.:Proc. Roy. 6oc. (Idondon)A174, 471 (1940). (5) HcafE-RorrrmRi-,IT.,ASI) ROWELL, 9. i V . : J. Inst. bIetals 38, 137 (1927). (6) JETTE,E. R., .&XU F o o m , F . ; J. Chem. Phys. 3, 605 (1935). ( 7 ) KORKILOV? I. I.: Bull. acad. sci. 1_'.11.S.S., C'lasse sci. math. nat., Ser. chim. 1937,313. ( 8 ) KORNILOV, I. I . : Compt. rend.a c a d . sei. IT.R.S.S.19, 1.57 (1938).
(9) RAYNOH, G . V.:Proc. Roy. Soc. (Loridon) A174, 457 (1940). (10) STEPANOV, S . 1.: AST) BVI..WH,S. A , : Cornpt. rend. acad. sci. L-.lt. 147 (1936). (11) STEPASOV, S . I., ..\si)KORXILOV, I. I . : . \ J I I ~ . s r c t e u r aiial. pliys.-chim.. Inst. chini. g6n. (L.S.6.R.)10, 7 8 , 97 (1938). (121 STOCKDALE, D.: .J. Iiist. .\IrtaIs 66, 287 (1940).
lteceiccd Junitai IJ 26, 19@
In continuation of btudie- on the solvent estraction of thorium started by two of us (G), we hare determined the distribution of thorium nitrate at room temperature between water and each of the following solvents: isoamyl alcohol, n-hexyl alcohol, methyl isobutyl ketone, methyl n-amyl ketone, and methyl n-hexyl ketone. These five organic solvents appear t o be the most promising for the liquid-liquid estraction of thorium nitrate from aqueous solutions also containing the nitrate5 of the rare earths and zirconium. The effect of added nitric acid has been ascertained on the systems containing 7%-hexylalcohol and methyl n-hexyl ketone. Some preliminary extractions with methyl n-hexyl ketone haye been described to show the applicability of the conclusions drawn from these distribiition data. DETERJIIS.iTIOS
O F DISTRIBUTIOS DATA
The experimental technique was that used in the earlier solubility work (G). Each system was composed of 5 ml. of the organic solvent (Eastman Kodak Company, practical grade) and 3 ml. of an aqueous phase brought t o the proper
concentration by the dilution of a saturated ilqiieouy thorium nitiate yohition. 'I'he test tube containing this sydem iras agitated end over end at 30 n . ~ . . \ r . for 24 hr. The phases were then separated, and each vas analyzed by direct ignition to thorium dioxide. The primary data (the percentages of thorium dioxide in each of the phases) are recorded in table 1, I\-ith other quantities calculated therefrom. Two sets of experiments n-ere made on methyl 72-hexyl ketone, one :it room temperature, the other thermostated at 25°C. i 0.05". Since the tn-o set> of data n-ere indistinguishable when plotted on the same graph (figure l ) , therniostating was abandoned for later runs. That the change Trith temperature is negligible with respect to the analytical errors is consistent with other data. lye have previously shoirn that the change of the solubility of Th(S03)*.4H20 with temperature in these solvents is no greater than the experimental error (6). Seidell (4) quotes Misciattelli ( 3 ) to the effect that the solubility of thorium nitrate in water (from separate sets of data) is:
The heat effect of the nitrate on passing from one solvent to the other i:, the difference between the two very small heats of solution corresponding to thebe tn-o small temperature changes (d In K / d T = 4 H / R T 2 ) . Consequently the change in composition of the system with temperature correqponding to the partition heat effect should be less than those shown by the simple solubilities. Data on the effect of increased nitric acid concentration on these distribution eqiiilibria \\ere desired, inasmuch as nitric acid n-ill probably be present in most aqueous nitrate solutions. The effect wab correlated with the quantity of nitric acid added t o the aqueous phase before mixing. Thus the aqueous phases, later mixed with methyl ?&-hexylketone, were made 0.5 S,1.0 Y, and 5.0 S in added nitric acid, respectively, for three bets of data, by the use of standardized acid solutions in mixing. T n o runs were made x i t h n-hexyl alcohol in which the aqueous phases irere 1.0 -1' and 5.0 S,respectively, in added nitric acid. These systems Tvere agitated and analyzed in the same manner as the unacidified systems. Mole fractions of thorium nitrate n-ere calculated on the approximation that each phase contained besides thorium nitrate only its respective solvent. The results are listed in tables 2 and 3 . All the above analyses were made as quickly ab possible to aroid the effects of chemical changes. Some measurements were made on the acidified systems after long periods of standing, and marked changes lvere noted. Coincident with these changes, gas evolution was observed similar to that noted in the previous solubility work (6). Thi, probably resulted from oxidation of the organic solvents by the nitric acid.
1008
B. F. IIOTHSCHILD, C'. C. TI-MPLIyammonki, g:iw 93.0 per cent and 93.24 per cent. This is an indication of the estent t o which thorium coulcl be eiiriciied in a single-step process, after t he original material is converted to nitrates. Liqiiitlliquid extraction ran then he applied mainly to materials :dreatly high in thorium.
Liq uid--liy Uid Cn.fracfioH -.lstaiting muterial \\.:is mixed from thorium, zirconyl, potassium, calcium, nitwtes. Hy calcwlation :md analysis. it contained 30.fi iind iwe earth per (wit thoria in the total osides precipitated by ammonia (thoriiim, zirconium. rare earth). Sisty-fivc grams of this in :I concentrated :tqueoiis solution ivas c~xtixrtecln.itli 30 ml. of methyl n-hexyl liptone for 21 h i . The layers \\.er
rotetl, the lietone \\-aslied \vith ivater. :ind tlie nitrates \\.ere crj7st:iIlizetl. This 0.8-g. p i w l i i r t :inalyzcd 94.7 per cent thoria in the total tien1-y oxide>. .In :ittempt t o ( m w n t i x t c tlic i.csidual aqueous solution 11)- henting cniisd the I o h s of Lihoiit half of t h p m:itci~i:il. The remainder \\xsreagitated \\.it11 the \vLishetl I;tltone; thc yicltl of this second extraction \ i x s 1 .;ig. of nitrate containing 89.0 pcl- cent tlioii:i in tlic total 1w:ivy oxides. That the potassium nntl cnlciiini \\.ere not ;xppi,wiaI)ly cxtixt*tccl\vas uscertainetl l)y othcr ignitions. It is wen t h a t thc yields are very dependent upon the exict concentixtiori of the initin1 aqueous soliition. 1here are many prohlems of manipulation inL-olvetl in liqiiid-liquitl cxtiwtion \\.it11 these solvents, \vhich must he solved liy furthrr ~ ~ o r l iThe . iodate method used here for thorium tends t o give resiilts atmit 1 per writ 1011.: t1ieidoi.c :ill enrichments given ai.? cwnserrative. . >
SUMMART
I . ('omplctc, dwt:i have I)em obtained for tlie distrihition of thorium nitrate hetn-em \vater and cuc*Iiof the folloiving solI-erits : methyl ,i-hexyl ketone, methyl n-amyl ket,one, methyl iso1)iityI lietone, isoamyl alcohol, and )i-hesyl : t l ( d i o l . Dist rihiition expiwsionH lial-e heen cal(*iil:itetl. clis;c~iissrct, :ind plotted.
1020
J . SH\l'IIIO
\SD I. 11. KOLTHOFF
2. The effect of added nitric acid on the systems containing methyl n-hexyl ketone and ?+hexyl alcohol has been investigated. 3. Preliminary leaching and liquid-liquid estraction runs with methyl n-hexyl ketone have been presented t o .;hoi\- the use of these solvents in extracting thorium from the rare earths and zirconium. This research was hupportetl in p a r t by the Research Committee of the University of Wisconsin Graduate School from funds supplied by the TT'iyconsin -Alumni Research Foundation.
THE BULKISES~ . L A D PORO>ITT OF SILICAPOWDER I. SH.iPIR0.
IYD
I. 31. KOLTISOFF
\rty o f lfinnesota, Mznneapolis 1 4 . l r / t r i i t l w / o
~ c h o o lof C ' h ~ i v z q t t y ,
iieceiuecl SoLember 13, 1947
From the studies oi Roller (15) on the bulkiness of \wious pon-der2 it follon-a that when the particle size oi a ponder decreases beluu :1 critical yalue, the bulkiness increases rapidly; and \I hen the particle size becomes greater than the critical diameter, the bulkiness of the powder mass remains essentially con,tant. For the several powders investigated the relation of bulkiness to particle s i z ~cun he expressed by the empirical equations: (I a)
and
1'
=
I
