882
T H E J O L - R N A L OF I-\-DCSTRIdL
the work of Wise1 in a recent study of
this
oil.
A C I D , S A P O N I F I C A T I O N , Ah-D I O D I N E K U L I B E R S .
The results of t h e measurements of the acid, saponification and iodine numbers are presented in Table I X and Figs. 7-9. The first two numbers represent the milligrams of potassium hydroxide necessary for one gram of oil, while the iodine numbers were optained by Hubl's method, being per cent. iodine absorbed by the oil. The acid numbers are seen to be generally additive for the mixtures, while the saponification numbers offer no general behavior. The iodine numbers are additive for t h e linseed and soya bean mixtures, the china wood mixtures, however, giving a hyperbolic curve. As the iodine number of the linseed is so much higher t h a n t h a t of the dogfish liver oil, this, as is well known, furnishes good evidence of the purity of the former. The numbers for the other vegetable *oils are so near those of the fish oil t h a t great value cannot be placed in these tests. Reference may be made t o the work of McIlhineya for a method of examining china wood oil. SUMMARY.
-.
I . The fluidities of fish a n d vegetable oil mixtures are additive, except where there is decomposition of either component on heating. 2 . The viscosities of these mixtures are also additive when the values for the components approximate each other closely. 3. The fluidities of vegetable oils are nearly linear functions of the temperature. It has been previously shown t h a t this holds true for various fish oils. 4. The fluidity of china wood oil, a s it is unusually low, is a good test of its purity. 5. The specific gravities of the mixtures are approximately additive a n d vary linearly with the temperature. The density of china wood oil is very high. 6. The index of refraction, acid number, a n d saponification number of the mixtures do not allow a n y general conclusions. The acid number of linseed oil is high, a n d t h a t of china wood oil low, compared with t h a t of dogfish liver oil. The refractive index of china wood oil is lowered by the introduction of small amounts of fish oil. 7 . The low iodine number of the dogfish liver oil makes the presence of this oil in vegetable oils known by marked lowering of their iodine values.
u. s. BUREAUO F FISHERIES, \vOODS
HOLE,M A S S . ; CLARK COLLEGE,WORCESTER, MASS., RICHMOND COLLEGE,RICHMOND, VA.
THE RELATION OF THE REFRACTIVE INDEX OF SODABARIUM AND SODA-LIME GLASSES TO THEIR CHEMICAL COMPOSITION. BY
A S D E.YGI.\-EERI-\-G
and by Lorentzz and Loren23 as wz-I
Ibid., 4, 496 (1912).
I
X K'. w " S 2 d This specific refractive power (K and K') represents a relation between the refractive index and the density of a substance and is nearly, b u t not quite, constant over a large range of temperature. I t is also dependent on both the chemical composition and the constitution, or structure, of the compound. The product of the specific refractive power and the molecular weight is known as t h e molecular refractive power and has been found, for many organic compounds, t o be the sum of its several atomic refractive powers modified b y the structure or atomic arrangement within the molecule. These relationships have been studied to only a limited extent in connection with silicates. Owing to our lack of knowledge of the compounds which are formed in a glass or of their atomic structure, the derivation of atomic refractive powers for the glass forming oxides is impossible. Investigations have, therefore, been limited t o the study of mixtures of pure silicates. Larsen4 has shown t h a t the specific refractive power of mixtures of calcium and magnesium silicate is a nearly linear function of the composition, calculated in percentages by weight, and t h e writer has shown5 t h a t this is also true, within limits, of soda-lime glasses. Neither the refractive index nor the specific refractive power of mixtures is necessarily a linear function of the composition. I n addition t o the changes in volume which may occur on mixing two liquids, there may be a similar change in the specific refractive power which may or may not be parallel with, or proportional to, the change in volume. Schutt6 and Pulfrich' have derived some rather complex formulae t o express these relations, both of which show excellent agreement with the experimental data. Schutt's formula is a s follows, A = -X I
k
- G ( a +-)'
in which K is the specific refractive power of the mixture, x k is the sum of the specific refractive powers of the components calculated by percentages b y volume, c is the percentage change in volume on mixing, b p ) is a factor dependent on a similar change and ( a in the specific refractive power. Pulfrich's formula is analogous t o the above and is as follows,
+
I ( = ' )
Received July 1, 1912.
THISJOURNAL, 4, 497 (1912).
Dec., 1 9 1 2
Nearly all of these expressions are based upon a constant known as the specific refractive power which has been defined by Gladstone and Dale1 as
EDWINWARDTILLOTSON, JR.
Many attempts have been made to discover the relation which exists between the refractive index and t h e chemical composition of substances, and many formulae have been derived t o express this relation.
CHEMISTRY.
I-c
' P h i l . Trans., 537 (1863). W k d . Amn.., 9, 641 (1880). 3 I b i d . , 11, 70 (1880). 4 A m . J . Sci., 28, 263 (1909). THISJOURNAL, 4, 246 (1912). 6 Z.Dhys. Chem., 9, 349 (1892). 7 Ibid., 4, 561 (1889).
*
= x k ,
Dec.,
T H E J O U R S A L OF IA-DUSTRI.4L ilLVD E,YGISEERIA'G C H E X I S T R Y .
1912
in which K , x k and G have the same significance as before and a is a factor dependent on the change in the specific refractive power. I n applying either of these formulae t o isomorphous mixtures, or t o mixtures which do not change in volume on mixing, the factor G becomes zero, and both formulae reduce t o K = x k . Mixtures of silicates closely approach this condition. The densities of glasses. differing widely in composition, are very nearly the same as those calculated1 from their components. We should, therefore, expect the specific powers of mixtures of silicates t o be a very nearly linear function of their compositions, expressed in percentages by volume. This paper is a partial account of a n investigation on the refractive index and specific refractive power of some soda-barium glasses for the purpose of throwing light on the relation between refractive index and composition and possibly t o identify compounds or doub e silicates which may exist. The preparation of the glass, the procedure adopted for carrying out these experiments, and the probable errors have been described in a previous paper.' The Gladstone a n d Dale formula for the specific refractive power has been employed throughout on account of its simplicity and ease of manipulation, and also because a large number of comparisons in this work have not disclosed any appreciable superiority of one formula over t h e other. The compositions of the glasses have been calculated as percentages b y volume in accordance with the formula of Schiitt and Pulfrich given above. The results obtained with soda-barium glasses are shown graphically in Figs. 1-4, in which the composition of the glasses is represented b y the abscissas and
1
I
1
o,3 :.;,.
I
1
;: :; :; ;;
:: :; I
I
1
20 80
30 70
W 60
50
60
50
YO
70 30
80
20
distinctly two straight lines meeting at a point corresponding t o a composition consisting of equimolecular proportions of Na,O and BaO-in this case Na,O.
BaO.gSi0,. This second line is also observable in the other figures, but is not so distinct because of t h e lack of data for glasses approaching barium metasilicate in composition. These glasses possess a very high melting point, crystallize readily and are subject
"s
u7
I
I
~
I
I 0
IO N.203Si0,
20
80
30
70
YO
50
60
SO
70
60
YO
SO
80
20
90 E e G L S r O ,
10
0
t o large experimental errors both in the composition and in the measurement of the refractive index. The data is sufficient, however, t o indicate the direction of the two lines. If the conclusion t h a t the specific refractive powers are additive is true, this change in direction of the curve indicates a compound a t the point where the break occurs, which in this case is of the type Na,O.BaO.xSiO,. I n Fig. j are shown, for comparison, the specific
I
;;a*+%
the specific refractive powers b y the ordinates. The glasses. whose specific refractive powers are shown in Fig I , varied in composition from Na,0.3SiO2 t o BaO.SiO,, those in Fig. 2 from Na,0.3.5SiOz t o BaO.SiO,, those in ,Fig. 3 from Na,O.~SiO, t o
0 /O /fo,OS5s,O,
883
u 90B,0S,OO, to
0
BaO.SiO,, and those in Fig. 4 from Na,O.gSiO, t o BaO.zSi0,. Fig. 4 is instructive in t h a t it shows Winkelmann and Schott, Ann. d. Phys. und Chem., 61, 697 (1894). Tillotson. THISTOURNAL. . 3.. 897 11911). . . * Tillotson, Lac. cit.
!
0
1
!O
Non03St0,
I
20 80
30
YO
SO
70
60
SO
60
70
YO
30
EO
20
;:(.OJ,O,
refractive powers of the soda-lime glasses, which were described in a former paper, recalculated and plotted in terms of percentages by volume. The results are, in general, the same as those previously found, and show plainly the two lines meeting a t a composition corresponding t o z Na,0.3Ca0.gSi02. I n Tables I t o V are presented the numerical data 1-5, respectively. The corresponding t o Figs. first four columns in these tables show the composition of the glasses in molecular per cent. and in percentages b y volume. I n the fifth column are given the densities as calculated from the composition ;I in the sixth, the observed refractive index for white light; and in the seventh the values of K, calculated, with the aid of Gladstone and Dale's formula, from the data in columns five and six. 1
Tillotson, Lac. cit.
884
T H E J O U R N A L OF I N D U S T R I A L A N D E K G I L V E E R I N G C H E M I S T R Y .
Dec., 1 9 1 2
TABLEI. BaO. NanO. BaSiOa. SiOn. 5101.per cent. Vol. per cent. Vol. per cent. Vol. per cent. I) calc. .... 21.9 2.41 0 78.1 2.515 2.3 21 .o 10 76.6 2.625 19.5 20 75.6 4.9 2.755 7.8 18.2 30 74.0 3.055 14.7 14.7 50 70.6 18.9 3.25 12.7 60 68.4 3.48 10.2 23.9 70 65.9 3.74 29.8 7.4 80 62.8 36.9 4.05 90 59.2 3.9
N ohs.
1.500 1.510 1.525 1.530 1.560 1.572 1.593 1.606 1.648
K ohs. 0.20747 0.2025 0.1999 0.1925 0.1835 0.1760 0.1705 0.1620 0.1520
K calc.
0.2075 0.2038 0.1992 0.1946 0.1830 0.1769 0.1702 0.1619 0.1521
1 ,5000 1.5126 1.5229 1.5361 1.5591 1 ,5749 1 ,5923 1.6055 1.6160
K ohs. 0.2062 0,2020 0,2005 0.1939 0.1931 0.1898 0,1860 0.1797 0.17156 0,16435 0.1520
K calc. 0.2066 0.2031 0.2001 0.1950 0.1932 0.1901 0.1843 0.1782 0.1720 0.1638 0.1538
N calc 1.4958 1.5057 1.5142 1.5284 1.5332 1 ,5408 1.5547 1.5702 1 ,5865 1.6019 1.6198
N ca1c:ohs.
K ohs. 0.2024 0.2000 0 1973 0.19196 0.18776 0.18316 0.1761 0.1676 0.1595
K calc.
?i calc.
0.2019 0.1992 0,1964 0.1920 0.1871 0.1823 0.1760 0.1675 0.1562
1.4947 1.502 1.5126 1.5261 1 ,5360 1.5524 1.5711 1 ,5899 1.6091
N cak-ohs. -0.0013 -0,0020 -0.0024 +0.0001 -0.0010 -0,0027 0.0001 -0.0001 +0.0016
K obs.
K calc.
0.2035 0.1983 0.1955 0.1898 0,1855 0.1820 0.1780 0.1735 0.1693 0.1648
0.2038 0.1993 0.1950 0.1903 0.1853 0.1816 0.1780 0.1738 0.1700 0,1650
N calc. 1 ,5085 1.5211 1.5304 1.5385 1.5466 1.5584 1.5718 1.5857 1 ,5967 1.6063
N ca1c.-obs. +0.0005 +0.0010 -0.0006 +0.0015 -0.0009 -0.0010 0.0000 0.0010 0.0022 4-0.0009
K ohs. 0.2085 0.2084 0.2085 0.2088 0.2092 0,2087 0.20866 0.21094 0.21310 0.21323
K calc. 0.2080 0.2080 0.2085 0.2087 0.2090 0.2090 0.2090 0.2107 0.2129 0.2129
N calc. 1.5054 1.5106 1,5172 1.5238 1 ,5330 1 ,5330 1 ,5433 1 ,5584 1.5791 1.5791
N ca1c.-ohs.
I\T calc.
N ca1c.-ohs. 10.0000
4-0.0026 -0.0021 0.0061 -0.0009 0.0029 -0,0007 -0.0005 +0.0012
+ +
TABLE 11. Sios. BaO. Na20. BaSiOs. Mol. per cent. Vol. per cent. Vol. per cent. 5'01. per cent. 19.4 80.6 0 79.7 2.0 18.3 10 78.3 3.8 17.9 20 76.7 7.O 16.3 30 76.0 8.0 16.0 331/3 15.2 10.0 74.8 40 72.7 13.5 13.8 50 70.5 17.8 11 .7 60 67.7 22.5 9.8 70 64.3 28.5 7.2 80 60.0 36.3 3.7 90
....
D calc. 2.40 2.49 2 .57 2.71 2.76 2.845 3.01 3.20 3.41 3.675 4.03
N obs. 1.495 1.503 1.515 1.5255 1.533 1.540 1.560 1 ,575 1.585 1.604 1.613
+0.0008 + O ,0027 -0.0008 4-0.0029 0.0002 + O 0008 -0.0053 -0.0048 +0.0015 -0.0021 0.0068
+
+
TABLE 111. BaO. BaSiOa. Sios. NaLO. &fd. per cent. Vol. per cent. Vol. per cent. Vol. per cent. D calc. 10 84.3 1.8 13.9 2.45 20 83.3 3.4 13 .3 2.52 30 82 . O 5.2 12.8 2.605 40 80.1 2.74 8.0 11.9 11.1 10.9 50 78.0 2.865 14.5 10.0 60 75.5 3.03 8.5 19.2 70 72.3 3.245 64 25.3 80 68.3 3.52 90 62.6 33.6 3.8 3.90
N ohs. 1.496 1.504 1.515 1.526 1.537 1.555 1.571 1.590 1.622
+
TABLEIV. iYa20. RaO. BaSiOa. SiOn. Mol, per cent, Vol. per cent. Vol. per cent. Vol. per cent. D calc. 10 77.8 2 .o 20.2 2 495 4.7 20 76.8 18.5 2.615 7.1 30 76.4 16.5 2.72 9.7 40 75.7 14.6 2.83 12.5 12.7 50 74.8 2.95 15.4 10.5 60 74.1 3 075 8.1 19.0 70 72.9 3.21 22.1 5.5 80 72.4 3.37 25.4 2.9 90 71.7 3.51 100 70.8 .... 29.2 3.675
h- ohs. 1.508 1.520 1.531 1.537 1.5475 1.5594 1,5718 1.5847 1 ,5945 1.6054
+ + +
TABLEV. CaSiOs. SiOn. CaO. XazO. Mol. per cent. Vol. per cent. Vol. per cent. Vol. per cent. D calc. 10 77.8 1.5 20.7 2.43 20 77.2 3.1 19.7 2.455 18.6 30 76.4 5.O 2.48 17.1 2.51 40 75.7 7.2 15.5 2.55 50 74.8 9.7 50 74.8 9.7 15.5 2.55 12.8 60 73.6 13.6 2.60 16.4 2.65 70 72.3 11,3 8.3 21.1 2.72 70 6 80 80 70.6 8.3 21.1 2.72
N oh;. 1 ,5064 1.5115 1.5172 1 ,5240 1.5334 1.5300 1.5425 1 ,5590 1.5796 1,5800
Since the speci6.c refractive power is additive for glasses of certain well defined compositions, i t is possible to calculate the specific refractive powers which the several oxides show in those glasses. They are as follows: S i 0n . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .0.1995 BaO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.0500 CaO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.2410 XapO.. . . . . , . . . . . . . . . . . . . . . . . . . . 0.2360
These empirical factors apply for glasses varying in
-o.noio -0.0009
*o
0000
-0.0002 -0.0004 0,0030 f0.0008 -0.0006 -0.0005 -0.0009
+
composition from the pure sodium silicates up to the point where the change in direction of the specific refractive power curve takes place and includes nearly all of the typical commercial glasses. The specific refractive powers and the refractive index of these glasses have been computed by the use of these factors, and are given in columns eight and nine in the tables. The specific refractive powers of the glasses which occur between the break in the curve and the
Dec., 1 9 1 2
THE J O U R S A L OF I - Y D U S T R I A L A N D E S G I h ' E E R I S G C H E A V I S T R Y .
pure barium and calcium silicates were not calculated from factors, but were taken from the curves in Figs. 1-4. It is possible t o derive factors which satisfy conditions for these glasses, but they are quite different from the factors given above and are unsatisfactory for calculating the specific refractive power for glasses of this composition. Kot only is the factor for every oxide different from those in the above table, b u t the same oxide may possess different refractive powers in different glasses of this type. For example, S O , possesses a different specific refractive power in soda barium glasses from what i t does in soda lime glasses and a different value in BaO.Si0, from what it does in BaO.zSi0,. This behavior is doubtless t o be explained as due t o the compounds which are present, and if so, will prove a valuable aid in determining the true constitution of a glass. To illustrate this point, the glass in Table IV, containing 9 0 molecular per cent. of BaO.zSiO,, has the following composition : Na20.Ba0.4Si02, . . . . . . . . . . . . . . . . BaO.ZSi02.. . . . . . . . . . . . . . . . . . . . . . . . . . . Si0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Per cent. 19.5 76.4
4.1
The specific refractive power of Sa,O.BaO.qSiO,, calculated from the factors given above, is 0 . 1830, t h a t of BaO.aSiO, experimentally found is 0 .1650, and t h a t of SiO, is 0 . 1995. Using these factors, the specific refractive power of a glass of the above composition is 0 . I 700-a value which is in fair agreement with t h a t found experimentally (0.1693) but which is not in harmony with the value calculated from a consideration of the oxides alone. S U M 51A RP.
Several series of soda-barium and soda-lime glasses have been made and their refractive indices measured. 2 . The existence of compounds of the types Na,O, BaO.xSi0, and 2Na20.3Ca0.xSi0, have been indicated. 3. The specific refractivities of these glasses computed with the aid of the calculated densities are additive from the pure sodium silicate up t c ) the double silicate and from the double silicate t o the barium or calcium silicate. 4. Factors have been derived b y which the specific refractive power of soda-lime and soda-barium glasses may be calculated within the limits described above from t h e percentages b y volume of the oxides. These are, for use m-ith Gladstone and Dale's formula, as follo~vs: I.
SiOz.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . BaO.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . CaO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
NazO ..............................
0.1995 0.0jOO 0.2410
0 2.360
5 . Since these factors have values which are characteristic of the compounds which may be present, a n exact knonleclge of these compounds is necessary for a thorough understanding of the optical behavior of a glass. DEPARTMENT O F ISDVSTRI.AL R E S E A R C H ,
YSIYEKSITY01:E;ASS.AS, I.AWI
