3096
NOTES
Vol. 76
running several spectral analyses during the course of this investigation. The author also wishes to thank S. E. J. Johnsen and K. M. Taylor for their assistance in the purification of cis-l-cyano-1,3butadiene.
Li2S04.H20, LisS04, LiNH4S04 and (NH&SOd. The diagram commonly used as an illustration of a classical ternary i ~ o t h e r m , ~is- taken ~ from a later report by the same investigators.1° It indicates only three solid phases : Li,SO4.HZO,LiNH4S04 and (NH4)2S04. The two diagrams~are based on MONSANTO CHEMICAL COMPANY the same table of data appearing in both of the PLASTICSDIVISIONRESEARCH LABORATORY TEXAS CITY, TEXAS above-mentioned reports. However, algebraic extrapolation" of the figures lends little support to the conclusion that LizSOk.Hz0 is a solid phase in Solid Solutions in the System Li2S04--(NH4)zS04- equilibrium with saturated solutions. In the later HzO' reportlo which also contains results of a study o f BY J. A. SKARULIS, H. A . HORAX,R. MALEENY,E. FELTEN the system a t 50' there appears a brief mention by AND R. S A V I N 0 the authors that Li2S04does not exist as a pure solid RECEIVED FEBRUARY 5 , 1954 phase a t 30 and 90' but in solid solutions, the n-c~ t ure of which they did not investigate further. Two Although the alums generally belong to the cubic other reference^'^^^^ to the ternary system a t 20, system there are three distinct internal arrangc- 57 and 97' contain no mention of solid solutions. ments of the structural units: a-, p- and y-struc- The presentation of results in these reports is fragt u r a 2 However, lithium aluminum alum is not mentary and pertains to the double salt LiNH4S04. cubica It would be intercsting to determine whether it forms solid solutions with alums having Experimental Procedure the various internal structures. The acquisition Anhydrous Li2SO4 mas prepared from J. T . Baker reagent of several well-formed ammonium aluminum alum Lid208 which had been recrystallized by the method of crystals which contained significant amounts of Kraus and Burgess.'( The final product was heated in platiin a mume furnace a t 550-600' t o remove the last lithium had led to the speculation that perhaps they num traces of acid and water. Merck reagent (NH4)2SOIwas contained lithium alum in solid solution.' A sys- used without further purification; It was pulverized and tematic study of the quaternary system Li2S04- then dried for several hours at 105 . Complexes of known compositions, totaling 50-60 g., Al&504)~-(NH4)zS04-H~0a t 0' was therefore underwere prepared in capped solubility tubes which contained taken in connection with this and with the general two glass marbles t o produce a grinding action during mixquestion of whether lithium alum formed solid solu- ing. They were brought to equilibrium a t 0" in a completely tions with alums possessing the different internal enclosed, well-insulated ice-water bath. T h e tubes were structures. Since the ternary system Li2S01- rotated end over end on a completely submerged wheel turned by a horizontal, motor-driven shaft which cntercd (NH&S04-H20 a t 0' had not been previously re- the bath through one of the sides. ported, a partial study of it was also necessary to The complexes were mixed 14-21 days before final andetermine the compositions of the isothermally in- alysis. I n most cases the saturated solutions were first variant saturated solutions. A more detailed analyzed after 7 days, the mixtures rotated for ai1 additional hours, and the solutions then reanalyzed. Constancy study of the system was made as a result of the dis- 48 of composition upon repetition of this process was used as a covery of solid solutions. Experimental evidence criterion of attainment of equilibrium. The procedure is presented below which indicates that the solid followed in the work at 25' was the same. The saturated solutions were sampled by means of pipets solutions are discontinuous and are actually bewith filter paper, and analyzed by one of two methods. tween Li2S04.H20 and LiNH4S04. A few results of fitted Coinplexcs 1-7 inclusive of Table I were analyzed for ama study of the same system a t 23' which substan- monia by distillation into excess standard sulfuric acid,l& tiate the occurrence of sdid sulutions at ;I highcr anti for lithium sulfate on separate samples by volatilization of ainmoniuni sulfate after evaporation t o dryness. Comtemperature also are given. plexes 8-32 were analyzed for total sulfates by evaporation It appears that the occurrence of solid solutions anti drying, and for lithium sulfate by ignition of the resiin the system I,i?SO.I-(~H,)nSO~-H.O a t various tlucs. Tlic first irietliod was adopted for IJart of the work at temperatures has bee11 ovcrlookcd ~ Y L L W of tlic 0" to shortcn thc time of analysis. 'Thc ~)i-owdureof the limited data aiitl the :~bsenc.cof ally irickttioii of scr:ond nietliod was that cinploycti i n a siiiiilar study of sditl solut iotis between aiiinioiiiutn sullatc a i i ( 1 ot h c alkali ~ solid solutiolis iii tlic graphical rel)resciitaticiris. iiictal sulfatrs.'6 It gave slightly higher a ~ i ~ ~ ~ i o nsulfate iitn~ The tliagraiii of the systerii at 30" rcprotlucctl in values, about 5 parts per 1000, thaii the first iricthotl 1)rchlellor5 is take11 froiii ai1 earlier report by Sclircine- surnably because the last traces of ciitrappctl -,vatvr iverc rciiiakers slid Cochcret.6 I t shows four solid phases: inovctl very slowly iii the drying ~irocess. A tracer tccli( 1 ) Tliis work W A S sul,litjrLcd in part I>y t h e Ka(ioiia1 Sciciice !'i,iiiidatirin Grant Gl;!!. ( 2 ) Primary references a n d i i dibcussioii 01 t h e criteria < I f ii,iniuriiliisin appear in Therald RIue!ler's "Inorganic Chcinistry," J o h n IVilcy aiirl Stma, N e w I'ork, N . Y., 1U33, p. ,511. (31 An X-ray study of the structure of lithium alum is in progress. I t ap!>ears t o be monoclinic. (4) J. A. N. Friend, private communication t o H. A . Horan. T h e limited amount of material permitted a n aluminum analysis only; calcd Alz(S01)i in NHdAl(So*)r.l2H10: 37 7 , found 37.0. T h e determined value should be higher t h a n t h e calculated if solid solutions of lithium alum were involved ( 5 ) J . W. hlellor, "A Comprehensive Treatise on Inorganic and Theoretical Chemistry," Vol. 11, Longmans, Green and Co., h'ew York. N v., 1922, P 706. 1': 2: .I !I. Sclireiiirmakcr, and D I f . Coclieret Cliene l i ' e e f i b l i . 1 , 2 , 771 ( I i i U i J .
( 7 ) l'arringtun Lkuiela, "Outliries of I'hysic~il CIiemi.lry," J C J h i i \Vilcy and Sons, Inc., New York, N. Y . , 1'348,p . 3 3 3 . (8) 1,ouis IIarnrnett, "lntr
