{ O l O ) , macropinacoid { loo}, and basal pinacoid { O O l ) ; (1011 and (011) are most predominant. Polysynthetic twinning on (110) and (170). Axial Ratio. a : b : c = 0.9750:l: 0.8045 (x-ray) ; not determined morphologically owing to multiple reflections caused by twinning.
hkO, with h # 2n. The corresponding space group is I 2/m 2/m 2/a. The literature space group is given as tetragonal P 4/nnm or a subgroup ( 5 ) . All Weissenberg patterns showed twinning on both (110) and (lio). Observations with a n electron microscope showed the twinning to consist of two sets of extremely fine, multiple, parallel layers. The latter were approximately 2000 A. in thickness, giving rise to continuous visible spectra on the crystal faces when these vvere viewed with an optical microscope. Tabulated powder diffraction data n-ere derived in the same manner as for a-A1Bl2.
ACKNOWLEDGMENT
Crystals n-ere obtained from A A. Giardini, of this laboratory (melt technique), and from P. G. Cotter, U.S. Bureau of Mines, Norris, Tenn. (aluminotherniic method). R. Lefker, of this laboratory, programmed the machine computations of d-spacings. G. Katz and L. Toman, also of this laboratory, assisted in some of the physical determinations.
X-RAYDIFFRACTION DATA Space Group. I 2 / m 2/m 2/a [tetragonal P 4/nnm or a subgroup (5)1. Cell Dimensions. a = 12.34 & 0.01 A , ; b = 12.631 & 0.005 A.; c = 10.161 =t 0.001 A. [Tetragonal, a = 12.55 A.; c = 10.18A. ( 5 ) ] . Formula Weights per Cell. 15.8. Formula Weight. 156.82. 0.003 grams per Density. 2.600 cc. (pycnometric in toluene).
LITERATURE CITED
*
CRYSTAL ~IORPHOLOGY Crystal System and Class. Orthorhombic, pseudotetragonal; orthorhombic bipyramidal class. Form and Habit. Pseudotetragonal bipyramids, rarely octagonal prisms with bipyramidal terminations; forms observed are orthorhombic bipyramid { 112 1, orthorhombic prism ( 110] , brachydomes { 011 1 and (021) , macrodomes { 101] and { 201 ]. brachypinacoid
OPTICALPROPERTIES Refractive Indices. 01, p, and y > 2.20. Surface Character. Continuous spectra in visible light, due to grating effect of twin lamellae.
FUSIOS BEHAVIOR Melting Point. 2200 helium a t 50 p.s.i.1.
I
50" C. (in
Determination of
Determination of Polymethylbenzyl Benzoates D. E. NICHOLSON, Humble O i l 8 Refinina- Co.,. Bavtown, . , lex.
*
cs-117 I
Slit
CRYSTALLOGRAPHIC data for publication in this section should be sent to W. C. McCrone, 501 East 32nd St., Chicago 16, Ill.
Cl~-CII Naphthalenes
Concn.
, I
Component Formula Name
8 . 8 5 ~0.112 I 0.028~ 0.027
0-100 &I
-
2,4,5-trimethyl benzoate -1-1-
benzyI-2,5dimethyl benzoate 2,4-Dimethylbenzyl-2,4dimethyl benzoate
,1
0-100 & I 112.23~ 0.218 10.042
2 2,4-Dimethyl-
3
-1-1
~
0-1001 A1
CisH2002
1 ~
Naphthalene
1-Methylnaphthalene 2-Methylnaphthalene 1,2,3,4-Tetrahydronaphthalene
oil 8 Rennins
1 1
Slif
Range
Accuracy
%
%
X or v
0.100
--CllHlo 0-100 h0.5
0.301
1 0.100
16.00p 0.214
1 0.100
I
I
CllHlo
--- I CloHlz
0-100 f0.5 I
Cell Windows: CsBr Absorbance Measuremenf:
Inverse matrix-Graphical-
Successive a p p r o x . 2 -
1 2 3 Material Purify:
298
0
8.85~ 0.398 0.127 0.220 9 8 % minimum
ANALYTICAL CHEMISTRY
Base line-
Inverse matrixGraphical-
P o i n t X Successive o p p r o x - L
Relafive Absorbances-Analyfical Matrix:
Relafive Absorbances-Analyfical Matrix: Componenf/X
Calculafion:
Concn. glliter lengfh mrn
0.389 1
Cell Windows: NaCl Absorbance Measuremenf: Calculation:
Av
0-100 h0.5
lnsfrumenf: Perkin-Elmer M o d e l 1 12, CsBr prism Sample Phase: Solution in carbon tetrachloride
P o i n t X
(mm) AX or
8.1. Pfs.
Jnsfrurnenf: Perkin-Elmer Model 21, NaCl prism Sample Phase: Solution in carbon disulflde
Base line-
C0.n
CS-118
CloHs
0.027
12.99~~0.255 1 10.048~ 0.027
HASTINOS, Humble
E* NICHOLSoN and 5. Baytown, Tex.
12.23~ 0.012 0.154 0.080
12.99~ 0.021 0.047 0.185
Componenflk 1 2
3 4 Material Purify:
20.98~ 16.150 0.251 6.908 0.101 99.5% minimum
18.68~ 0.072 3.507 0.015 0.046
16.00~ 0.302 0.115 1.111 0.048
23.02~ 0.030 0.377 0.042 1.459
