CALCIUM OXALATE-CIILORIDE 1)ouBLe SALTS
July, 194(i
where T r is the reduced temperature, T / T c . By coiiibining this equation with the equation for t tic sun1 of the densities PL
+
PV =
+ Bt +
$2
the densities can be calculated from room temperature to within about 5' of the critical point. I'he values of the constants k, nz, n, a, p , and y evaluated for each of tlic coinpounds froin the t.xperirnenta1 data arc given in Table 11. Included in this table are the average deviations of the obierved from the calculated values for both thc vapor pressure and density. The agreement Iwtween the observed and calculatecl values is withiti thc expcriiriental error in the data. A coiliparison of tlir vaI)or pressure and density tlata calculated for n-hexane and 2,3-dimethylbutane with data reported by Young' is shown in Table 111. Summary The critical coilstants of all of the isomeric 1. hexanes and the standard boiling points of all except 2,2-diiiietliylhut~lllc wcre carefully de-
[CON'IRIRUlION FROM T I I E
WBSlERN
133.39
termined. Values of the liquid density a t 20' were obtained by interpolation of the densitytemperature curves. 2. The vapor pressures and saturated liquid and vapor densities of the isomeric hexanes were determined from near their atmospheric boiling poiiits to their critical points. The data have Iwen reprc.c;eritecl by einpiric:il equations: ( a ) t l i r va1)or 1)ressur.ctl:Lta 1)y cquatioris of tlir typc log P =A ( U / 7 ' ) with tlic aid of deviatioii curves; (b) the density tlata by means of tlie equation of Fales and Shapiro, log log PL/PV = log k 4-vi log (1 - T:) - n log Tr together with the ecluntion for the suni of the liquid and vapor dcnsitics, PI, f P V = N f fit $ Y f 2 . Val11CS ( J f thC' coirstuits i l l thc cquxtions are given for each Iiydrocarboii.
+
RECEIVED NOVEMBER ~~ 5, 1942 (11) Thi? manuscript was originally received on NovernbPr 5 , 1!142, :Lnd after tarnination by the Editorial Board was accepted for jitiiilic.!tii,u in the Journnl. It mas, however, referred to the Nijtioiiitl I k f r i i s e He.e:trcli Committee. .rnd u t their request was withheld from pulilicatiou, in R contide1iti:il file, u n t i l clenraucr wiis granted oii J.inti,iry I O l ! l l l ;
RIXIOSAL RITSBARCII r.AIIORA1'ORY1 1
The Composition, Optical and Crystallographic Properties of Two Calcium OxalateChloride Double Salts BY FRANCIS T. JONES
AND
When microscopical methods'" were employed for the identification of minute crystals of calcium oxalate found in asparagus juice and hemlock bark, two crystalline substances were observed whose optical properties indicated that they were probably new compounds. Analysis shows that these compounds are the double salts CaCz0,. CaC12.7H20 and CaCz04CaC12.2H20. A careful search of the literature failed to reveal any work on the calcium oxalate-chloride double salts later than that of G. RaineyZin 1865. He investigated the oxalate-chloride double salts of the alkaline earth elements and, among others, described the compound CaCz04.CaCl2.7HzO that appears to be the same as one of the two reported here in detail. This compound had been prepared earlier by Frit~sche,~.' who also described another double salt of the composition 3CaC2O4. CaC12.8HzO. Souchay and Lensens in 1856 reported a double salt having the formula 4CaCz0,. (1) Bureau of Ayriculturdl and Industrial Chemistry, Agricultural Research Administration, U.S. Department of Agriculture. Article not copyrighted. ( l a ) Chamot and Mason, "Handbook of Chemical Microscopy." John Wiley & Sons, New York, N.Y . , 1938. ( 2 ) Kainey, Proc. Roy. SOL. (London), 14, 144 ( 1 8 6 5 ) . (3) Fritzsche. P o g g . A n n . d . Physik u. Chemic, 38, 121 (1833). (4) Fritssche, Jahresberichl uber de Forlschrille der Chemic, 372
(1864). ( 5 ) Souchay and Lensen, Ann., 100, 317 (1856).
LAWRENCE M. WHITE
CaC12.24HzO the existence of which was later doubted by Fritzschen4 Experimental Microscopical Observations.-When crystals o1)tainerl from asparagus juice or hemlock bark were recry
