V O L U M E 23, NO. 2, F E B R U A R Y 1 9 5 1
379
oxygen, based on a 1-gram sample, for a 10-minute analysis. This is higher than normal blanks (0.0005 t o O.OOl%), but could be decreased with longer degassing time. (Four hours at 2000 O C. were used in t,his work.) However, the blank as found is accurate enough for most sampltxs with high oxygen content. Oxygen content of the tin uscd for dilution was found t o he 0.007%. R ESU LT S
Some typical results and operating conditions are givrri in Table I. The results approximate the oxygen suspected in the samples prepared by deliberate additions of oxygen or by Lilliriidahl’s chlorine method ( 4 ) . The oxygen determined by vacuum fusion is higher than t h a t estimated by doping-i.e., oxygen is added deliberately by oxidation and t,he weight increase is determined; this might be expected if the oxygen content of the starting material before doping is not accurately known. The agreement between the vacuum fusion method and the chlorine mtlthod is reasonably good.
The vacuum fusion method is very rapid, as it requirrs only about 20 minutes per sample. LITERATURE CITED
(1) Derge, G., J. Metals, 1, 31-3 (1949).
(2) Kelley, K. K., U. S. Bur. Mines, Bull. 476 (1949). (3) Kroll, W.J., and Schlechton. A. W., Tmns. Electrochem. Soc., 93, 247-58 (1948). (4) Lilliendahl, JT. C., Wroughton, D. M., and Gregory, E. D., J . Electrochem. SOC.,93, 235-47 (1948). (5) McGeary, R. K., Stanley, J. K., and Yensen, T. D., Trans. Am. SOC.Metals, 42, 900-16 (1950). (6) Prescott, C. H., J . Am. Chem. SOC.,48, 2534-50 (1926). (7) Read, E. B., and Zopatti, L. P., “Determination of Oxygen in Zirconium Metal.” Pittsburgh Conference on Analytical Chemistry and -4pplied Spectroscopy, Pittsburgh, Pa., Feb. 15 to 17, 1950. (8) Reeve, L., Am. I n s f . M i n i n g Met. Engrs. Trans., 113, 82 (1934). (9) Walter, D. I., ; i s . i L . CHEM.,22, 297 (1950).
RECErVED June 16, 1950. Laboratories.
Scientific Paper 1525, Westinghouse Research
Effect of Temperature on Density and Refractive Index on Organic Compounds of Various Cox Chart Families R . R. DREISBACH T h e Dow Chemical Co., Midland, Mich.
THE author’s paper on the Eykman equation ( I ) , it was demIa n donstrated t h a t this empirical equation relates liquid density refractive index accurately for a narrow temperature range S
around room temperature. Kurtz, Amon, and Sankin ( 4 )demonstrated t h a t this equation was applicable over a wide range of temperature. Ward and Kurtz ( 5 , 6 ) iecommended t h a t the empirical equation, An = 0.6 Ad, was accurate for hydrocarbons for small changes of temperature, and a column in the tables ( 4 )demonstrated the variation of the value of ~ E Icalculated by this formula from determined values Griswold ( 3 )differentiated the Eykman equation:
(n2 - 1) (n
1
+ 0.4) x -d = c
and obtained: An/Ad = dn,/dd =
+ 0.4)’ + 0.1)2 + 0.81
C(n (n
Griswold ( 3 )demonstrated t h a t the coefficient 0.6 was good for hydrocarbons where the C value was 0.74 or greater, b u t t h a t where the C value was low, as in the case of nonhydrocarbons, the coefficient of proportionality b e t w e n n and d might be as low as
0.3. Iheisbach and Martin tabulated the C values for 98 organic compounds in 15 Cox chart families. This C value varies from 0.80806 for m-divinylbenzene t o 0.31522 for 1,2,3-tribromobutane. This coefficient is in all cases very close t o 0.80 times the C value and, hence, the variation of refractive index with density can he represented by: An/&! = 0.SC
Table I. Refractive Index at 20” C., C Value of Eykman Equation, Variation o f Refractive Index with Density, a n d Ratio of Variation with C Value Compound
1.37500 1.50110 1,52406 Chlorobenzene o-Dichlorobenzene 1,55145 1.55972 Bromobenzene o-Dibromobenzene 1.51101 1,53763 1-Ethyl-4-vinylbenzene 1-Brorno-3-vinylbenzene 1.59268 1,57610 Divinvlbenzene 1.37850 Methyl ethyl ketone 1.42913 n-Octyl alcohol 1.37160 Acetic acid 1.37239 Ethyl acetate Xitropropane 1.40161 1.54662 Nitrotoluene 1.41195 n-Amyl ether 1.50735 Phenetole 1.52521 p-Chlorophenetole 1,52684 Propionphenone 1.36638 Propionitrile 1,53262 8-Phenylethyl alcohol 1.54178 Phenol 1,58545 Aniline 1.4021 1 n-Butyl chloride 1.43901 1,2-Dichloropropane 1,50534 Perchloroethylene 1.53865 1 2-Dibromoethane 1,58597 1’2 3-Tribromoethane 1,46006 Carbon tetrachloride a Values from (1); all the rest from ( 8’).
C 0.76093 0.75000 0.62170 0.55211 0,48900 0.40000 0.78880 0.54459 0.80806 0.60854 0.47428 0.69036 0.55346 0.53488 0.61809 0.70009 0.69101 0.61209 0.68425 0.61778 0.68402 0.67055 0.74616 0.60481 0.50377 0.40947 0.32366 0.31822 0.38171
dn/dd 0.600 0.608 0.510 0.452 0.401 0.331 0.644 0.449 0.665 0.481 0.552 0.374 0.436 0.425 0.506 0.557 0.561 0.499 0.558 0.495 0.558 0.548 0.615 0.480 0.404 0.329 0.264 0.260 0.307
(l/C) x (dn/dd) 0.79 0.81 0.82 0.82 0.82 0.83 0.82 0.82 0.82 0.79 0.80 0.79 0.79 0.79 0.82 0.79 0.81 0.81 0.81 0.79 0.81 0.82 0.82 0.79 0.80 0.80 0.81 0.82 0.80
that) the difference between the two values of An is 0.0001 and, hence, when the value 0.80 is used the error in An v\-ould be less than 0.0001. LITERATURE CITED
(3)
The relat,ionship of Equation 3 holds a t temperatures of 10’ C. u p to 50” C., a t least in every case tested. Table I records the C value, the refractive index a t 20°C. ( n g )from ( 1 , 2 ) ,the dn/dd values calculated by means of Equation 2 and the ratio (dn/dd)/C. I n every case the ratio of Equation 2 lies between 0.79 and 0.82, except in the case of o-dibromobenzene, where it is 0.83. When the coefficient 0.80 in Equation 3 is replaced by 0.79 in one case and 0.82 in the other, it is found
n ‘2
(1) Dreisbach, R. It.,I n d . Eng. Chem., 40, 2269 (1948). (2) Dreisbach, R. R., and Martin, R. A., I b i d . , 41, 2875 (1949). (3) Griswold, J., Ibid., 42, 930 (1950). (4) Kurte, S.S., Jr.. Amon, S., and Sankin, A., I b i d . , 42, 174 (1949). (5) Ward, A. L., and Kurtz, S.S., Jr., ISD. EXG.CHEM.,ANAL.ED., 10, 573 (1938). (6) Ward, A. L., Kurte, S.S.,J r . , and Fulweiler, W. H., “Science of Petroleum,” Vol. 11, P. 1146, London, Oxford Universitv Press, 1938. REChIVED
lhIay 29, 1950.
