I446
H . h I . S J I I T H A N D IV. 1%. N C C t . E I . L . % N D .
and, therefore, are solid solutions containing a small amount of the sulphate in the hydroxide. In view of the well-known property of hydroxides to carr!. dotvn other substances \vith them \\-hen precipitated and thc titter iinprohahilit!. of any molecule of so large a ratio of base to acid. thc latter coiiclusion st'cnis j us t i fia hl e. I am pleased to ackno:vletlge the efficient help of m). assistant. l l r . H. 1:. Pulsifer. \vho did rn:ich of the analytical work and of Mr. 11.A. Stel\-art. \vho tleterininetl the extent of hydrolysis ot' the normal sulphate i n solution and the effect upon the atnoiint of L
H ions present obtained by saturating the same solution n.ith its o\vn carbonate. The folloiving conclusions seem warranted : That the onl!. known definite h!.drated sulphates of beryllium are BeSO, 1H,O and ReSi), zH,O. That the anliydrous sulphate BeSO, is difficult to produce entirely free from water or crcess of oxide, owing to the difficult!of removing the last traces of water without a t the same time driving off sulphuric anhydride. That the so-called basic sulphates of beryllium do not erist as separate ant1 definite chemical compounds, btit are in reality solid solutions of the sulphate i n the hydroxide. These are much more basic i n composition \\hen equilibrium with the mother-liquors i j reached than ivlien first precipitated.
+
+
h-b:W HA.\IPSHIKE COI.Li.l,E.
DCIIHAX
N. H.
ON T H E AOLECULAR DEPRESSION CONSTANT OF j-AZOXYANISOL. BY H . X O N M O U T H
S M I T H ANI)
Received Auqii>t
U'. H. I,
>ICCLLI,LANI>.
1904.
Gr\TTERhf:ls.'T and Ritschkel first prepared p-azoxyanisol and found that a t 116' it passed into a turbid liquid of fluid crystals, which at 134' became a clear, transparent yellow liquid. Schenck,? in studying the compound, showed that both these transition p i n t s undergo abnormally large depressions, and from the depression of the "clear-turbid" transition point by seven 1 9
Ber. d. chrm. Gts.. a 3 , 1733. Ztschv, phyi. Chem.. 25, 349.
DEPRESSION COKSTANT OF P-AZOXYANISOL.
'447
solutes of various composition he calculated the molecular depression constant as 750.2. Later,l from determinations with eighteen solutes, he found values ranging from 503 to 859. ;iiiwers2 reported the value 545 as the average found by one of us^ from determinations made with five solutes. In another series of determinations he reported4 values ranging from joo to 700. Such a large depression constant is of special interest because of its size, and because, if it can be determined with accuracy, it will permit molecular weight determinations with the consumption of but a few milligrams of the solute. It seemed of interest then to redetermine this constant in the hope that more c m cordant results might he obtained. The apparatus which was used in these experiments was of the usual Beckmann form, with a constant temperature bath of glycerol. The thermometer was divided into tenths of a degree and had been verified by the Reichsanstalt. T h e azoxyanisol was prepared according to the method of L a ~ h r n a n ,for ~ azobenzene, and had transition p i n t s of 116"and 134". T h e solutes were all of Kahlbaum's manufacture and gave sharp and constant meltingpoints. Especial care was taken with reference to the conditions necessary to obtain uniform results and the following points may be mentioned : ( a ) The glycerol bath must be at the highest possible temperature which will, at the same time, allow the formation of the fluid crystals. With the apparatus used in these experiments this limit was found to be from 2.5" to 3" a b v e the transition temperature of the azoxyanisol. If the bath varied from this limit b>- a degree, the transition point was found from 0.5" to I " too high. i b ) As a consequence of ( a ) it was found that any deviation whatever in the temperature of the bath during a determination gave discordant results which amounted to 4 per cent. for a temperature change in the bath of 0.5". ( c ) I t was also noticed that the transition point of the freshly prepared azoxyanisol did not remain constant, but showed a grad1 1
3 4
5
Zlschr phys. Chcm., 29. 554. Ibid,33,60 H. M S . Zlschr phys Chcm , 42, 631 This Journal, 24, 1178 I
I448
H. M . SMITH A N D W . H . M C C L R L L A N D .
ual rise (luring the first half--hour of h e a t i n g , after \ v h i c h it Ixcame constant and remained so indefinitel!-. The results of the determinations are g i v e t i in Tallle I. T.4131,~ Grams solvent.
Crams solute.
I
Observed depression.
Naphthalene, molecular
s 8 8
8 8 8
8
8 8
0.0562 0. I 164 o.17oj
3.09 6.49 9.46
(:ranis solute in roo grams solvent. weight 12s.
JIolecular depression constint. K
0.7025 1.4550
56I
2.1310
-
5 70
566
Average, 566 a-Nitronaphthalene, molecular weight 173. 0.0616 2.61 0.7700 5 86 0. I 188 5.17 I , 4840 60I 0.1659 7.77 2.0737 598 Average, 595 Anthracene,' molecular weight I 7s. 0.0586 2.20 0.7325 5 36 4.61 I .63P 5"3 0.1311 0.202I
7.14
503
2.5260
8
Average, 5 14 o-.%cetotoluide, molecular weight 149. 0.0627 3.51 0.782I 624 0 . I 207 6.69 1.5081 617
8
0.1626
8
9.26
2.0330
633
Average, 625 Acetamide,' molecular weight 59. 8
0.0589
6.83
0.7362
546
8
0.05S2
6.I U
0.7275
495
8 8 8
8 8 S
Average. $-Acetotoluide, molecular weight 149.
52 I
0.0548 0.1042 0.741I
0.6844
542
I .302O
554 544
2.49 4.84 6.44
I . 7640
Average. Phenetol, molecular weight 122. 0.0321 I .S5 0.4006 0.0981 5.65 1.2250 0.2095 12.25 2.6130 Average, Citinamic acid, molecular weight 148.
8 8 8
0.051j 0.I 1 4 7
0.1606
2.59 5.47
7.31
0.6437 1.4330 2.0070
Average, Grand average, 562. 1
Slightly volatile.
I449
D E P R E S S I O N C O N S T A N T OF $-AZOXYANISOL.
This average of 562 agrees better with that of 545, found by Auwers than with that found by Schenck. Among the solutes used by Aciwers1 was benzil, which gave a value of 860 for the depression constant. I his was so abnormal that it was not included by him in the average which he gave. O n repeating this determination we obtained likewise an abnormal value which led 11s to try the action of three other bodies of ketone structure, the results of which are given in Table 11. TABLE11. Grams solvent.
Grams aolute.
Observed depression.
Gram4 solute in IW grams solvent.
B e n d , molecular weight 8
0
8 8
0.1310 0.2014
0571
2.80
6.20 9 81
Molecular depression constant, K .
210.
0.7137 1.6370 2.5170
824 795 818 _ .
Average, 812 8 8
8
Benzoin, molecular weight 212. 0.0619 3.52 0.7738 0.1176 6.83 1.4700 0.1714 9.64 2.1420
963 984 964
Average, 967
8 8 8
Benzophenone, molecular weight 182. 0.0511 2.81 0.6387 0.1032 5 60 1.2890 0.1512 8.24 I .8gm
795
8 8 8
Average, Michler’s ketone, molecular weight 168. 0.0367 1.24 0.4587 0.0817 2.84 1.0200 O.IZ00 3.94 I. 5 m Average,
724
502 790 793
723 745 705
Grand average, 825.
T h e average of these four ketones gives a depression constant of 825, or 32 per cent. higher than that found by the eight substances in Table I. T h e differences between the values heretofore found. for the molecular depression constant have been attributed by Hulett2 to the possible solubility of the solutes in the fluid crystals. Since 1 9
Zfschr.phys. Chon., 3 2 , b . Ibid., 28,642.
1450
H.
E . PATTJIS A N I )
\\'.
K . MOTT.
our deterininations have hc't'i! iiiac!e, (le Kockl Isis sho\vn, in a i l eshaustive study of the subject. that such is the case, and that a m a l l difference in the solubility co
