INDUSTRIAL A N D ENGINEERING C H E - I S T R Y
May, 1924 TABLE II--OBSBRVED
AND CALCULATED SPECIFIC VOLUME3 O F THE
40.27
PERCENT MIXTURE FROM IOo TO 80’ C .
Tem- Volume per- Per cent ature Mineral C . Seal Oil 10 20 30 40 50
41.84 41.92 41.94 41.97 42.01 42.02 42.04 41.86
A p e c i f i c VolumeObserved Ideal 1.1610 1.1706 1.1795 1.1888 1.1975 1.2066 1.2164 1.2270
1.1611 1.1714 1.1801 1.1893 1.1983 1.2075 1.2171 1.2246
60 70 80 Per cent average directional divergence:
Per cent Divereence i0.002 +0.08 10.05 t0.04 fO.07 f0.08 4-0.05 -0.20 1 0 . 02
Specific Volume B., H., and H. 1.1623 1.1727 1.1814 1.1907 1.1998 1.2091 1.2186 1.2259
Per cent Divergence 10.10 10.19 10.16 4-0.16 10.20 10.21 1 0 . 18 -0.09 +O. 14
The behavior of the system Nujol-Mineral Seal Oil can, therefore, be impugned in no way as divergent from that expected of a mixture of two inert hydrocarbons. If this behavior appears anomalous to believers in the Bingham fluidity theorywho, it is implied,&must accept it as an act of faith in the teeth of hostile data-one can only cite the example of Mohamet and the mountain. As one of the unregenerate, I would express, in closing, my admiration and personal esteem for Professor Bingham and his collaborators. Their constant industry and zeal, comparable only with that of the faithful of Islam, may well be an example in this obscure field. 1 KENNETH P. MONROE PENN’SGROVE, N. J. January 21, 1924
.. . .. . . .
Editor of Industrial and Engineering Chemistry: When Mr. Monroe states that “believers in the Bingham fluidity theory * * * must accept it as an act of faith in the teeth of hostile data,” we must suppose that he has pretty strong evidence against the said theory. This evidence should be most welcome t o all, for theories are but stepping stones of thoughthelpful for the time being, but useless, if not worse, when they have served their purpose. In no case is a scientific theory to be taken on faith, but always must rest upon pertinent data. But data can never be described as “hostile.” Facts are always friendly-to the truth, and the truth is all that counts. Mr. Monroe correctly states that the ideal specific volumeweight concentration curve is linear. He is also correct in stating that the ideal specific volume-volume concentration curve is hyperbolic.6 He is incorrect in assuming that in a particular case one may not have a linear specific volumevolume concentration curve to within experimental error. We should expect a linear specific volume-volume concentration curve when the specific volumes are identical, as I have pointed out.6 The mixtures criticized by Mr. Monroe are exceptional. Nujol and Mineral Seal Oil differ widely in fluidity-viz., 2.889 to 28.6 at 40’ C.-but their specific volumes differ but littleviz., 1.156 to 1.239 (not 1.2491 as given by Monroe). These values are so nearly the same% that the divergence from linearity in the specific volume-volume concentration curve is not so much as 0.2 per cent. It is entirely proper for Mr. Monroe to regard this curve as hyperbolic, but the deviation is so near the experimental error that it is quite inadequate to account for the 32 per cent deviation in fluidity. The calculations by which Mr. Monroe supposes that he has uncovered the “colored gentleman” were.made by Mr. Hyden, and both curves are given in Mr. Hyden’s thesis. The small amount of curvature found was never regarded as an evidence of nonideality. The second contention of Mr. Monroe is that in no ideal system yet investigated has a linear fluidity-volume concentration curve been encountered. He ignores completely all work done on this subject since his 1921 paper. This can hardly be ignor4 Bingham, “Fluidity and Plasticity,” 1922, p . 105. McGraw-Hill Book Co.,New York. 6 I b i d . , p. 162. 0 Bingham, A m . Chem. J . , 5 6 , 199 (1906); “Fluidity and Plasticity,”
p . 90.
535
ance on his part, because references were carefully given to this work in the paper which he is now criticizing. The purport of the recent work is as follows: (1) Fluidities should be additive only when volume concentrations are used. ( 2 ) The specific volume-volume concentration curves are slightly sagged, even when the components are inert. (3) The fluidity curves will, therefore, be similarly sagged even when the components are inert. That the fluidity curves are sagged is generally agreed to be the fact. Moreover, the greater the difference in the specific volumes of the component the greater the sag in the specific volumevolume concentration curve and, therefore, the greater the sag to be expected in the fluidity-volume concentration curve. In studying the data of Kendall and Wright,’ which were found not to conform to any other formula, BrownS found that the foregoing prediction was verified. The greater the deviation from the theory in the specific volume-volume concentration curve, the greater the deviation in the fluidity-volume concentration curve. The fluidity differences are in the same order as the differences in specific volume. By making a correction for this, the fluidities are found to be additive, with an averagedeviation of 1 per cent in the cases of ethyl benzoate and benzyl benzoate, phenetole and diphenyl ether, ethyl acetate and ethyl benzoate, and diethyl ether and phenetole. So far as we know, these facts, first reported a t the Rochester meeting of the AMERICANCHEMICAL SOCIETY, have never been challenged. In our opinion they fully justified the statement, objected to by Mr. Monroe, that Nujol and Mineral Seal Oil were particularly suited for investigation because on mixing they give a specific volume-volume concentration curve, which makes unnecessary any correction on account of change in volume on mixing. In the eighth paragraph of our paper “February, 1922” should read “February, 1923.” E. C. BINCHAM E A S T O N , PA February 13, 1924 7 8
J . A m . Chem. SOC.,42, 1776 (19201. Bingham, “Fluidity and Plasticity,” p 168.
Photographic E xhibits VVa nted Editor of Industrial and Engineering Chemistry: The Royal Photographic Society of Great Britain will hold its 69th annual exhibition in September and October. This is the most representative exhibition of photographic work in the world, and the section sent by American scientific men heretofore has sufficiently demonstrated the place held by this country in applied photography. It is desirable that American scientific photography should be equally well represented in 1924, and, in order to enable this to be done with as little difficulty as possible, I have arranged to collect and forward American work intended for the scientific section. This work should consist of prints showing the use of photography for scientific purposes and its application to spectroscopy, astronomy, radiography, biology, etc. Photographs should reach me not later than Saturday, June 14. They should be mounted but not framed. There are no fees. I should be glad if any worker who is able to send photographs will communicate with me as soon as possible, so that I may arrange for the receiving and entry of the exhibit. A. J. NEWTON EASTMAH KODAKC O M P A N Y ROCHESTER,N. Y. April 16, 1924
Correction-In the report of the National Association of Glue Manufacturers, on “Standard Methods for Determining Viscosity and Jelly Strength of Glue” [THIS JOURNAL, 16, 310 (1924)], footnote 4 on page 315 should read: THISJOURNAL, 15, 571 (1923).-[F. L. DEBEUKELAER]
