« iepriekšējāTurpināt »
A quantitative study of adsorption in solution and at interfaces of sugars, dextrin, starch, gum arabic and egg albumen, and the mechanism of their action as emulsifying agents: GEORGE L. CLARK and Wm. A. MANN. By the most accurate method known—the use of the stalagmometer for measurement of interfacial tension and the Morgan drop weight apparatus for measurement of surface tension of single liquids—the adsorption of sugar in solution has been determined to be negative, the adsorption increasing in ratio with increase in concentration of sugar, while the adsorption of sugar at the interface is positive and increases in the same ratio as in solution. Dextrin and starch, in very dilute solutions, are negatively adsorbed in solution but, in more concentrated solutions, are positively adsorbed while at the interface they are negatively adsorbed-starch more so than dextrin. Gum arabic behaves, in this respect, in the same manner as starch. A favorable surface tension, seemingly, is not a prerequisite for a good emulsion with any solution studied, although viscosity is an important factor. Better emulsions have been obtained with egg albumensaturated solutions—than with any other solution under inspection,
The preparation, properties and molecular vol ume relationships of the ammines and hydrates of cobaltous fluoride, bromide, nitrate, carbonate and citrate: GEORGE L. CLARK and H. K. BUCKNER,
The molecular volume compression of the subsidiary valence groups, NH, and H,O, were studied in the same manner as in the previous work on the chloride and sulphate of cobalt (J. Am. Chem. Soc., 42, 2483 (1920)) in light of difference in volumes between anion and cation and possibilities of space cavities. It was confirmed that the larger the difference between anion and cation the greater the possibility of cavities, and the less the compression of NH, and H,0 required the more stable the compound and the greater the possibility of holding a maximum number of groups. The various compounds prepared and studied are distinctly new with the exception of cobaltous bromide hex. ammine and cobaltous nitrate hexammine, the following being representative: cobaltous fuoride hexammine, cobaltous nitrate di-hydrate, ammines of cobaltous nitrate indicating more than six subsidiary valence groups and ammines of cobaltous carbonate and citrate,
Emulsification with soaps of linoleic and ricinoleic acids : GEORGE L. CLARK and H. K. BUCK
This work has involved the quantitative study by means of surface energy measurements for solutions and at the interface between aqueous solution and a pure oil by the drop weight method of the following points: the solubility in water of the free acids from the log. concentration-surface tension curve; the adsorption at the surface and the volume occupied by each molecule in the surface; the surface tensions of various concentrations of the soaps in solution, the effect upon the interfacial tension between water and pure toluene, the effect of the hydrolysis of the soap and the prevention of hydrolysis by the addition of various concentrations of NaOH to a given concentration of the soap; a test of the antagonistic effect of sodium and calcium soaps by testing the effect upon the interfacial tension between water and toluene containing a small amount of the free acid of adding various salts of sodium and calcium, resulting in the fact that the sodium salt promotes emulsions of oil in water and calcium salts promote emulsions of water in oil; and finally a thorough comparison of all the data so obtained with previous work on soaps of palmitic, stearic and oleic acids. All results of this purely quantitative study, are necessarily numerical and can not be included in a short abstract.
Notes on the preparation of pure platinum: EDWARD WICHERS. The paper briefly states the method used in preparing platinum sponge free from other platinum metals and base metals, and describes in more detail the work that has thus far been done on the conversion of this sponge to compact metal with minimum contamination, E.M.F. tests show the resulting platinum to be of higher purity than the best previously obtainable, i.e., the thermoelement wire of Heraeus, and show the difference in purity to be a matter of calcium content. Results of experiments with magnesia refractories are also given. There is a brief outline of further work to be done on this subject.
Modified method for the determination of iron and vanadium after reduction by hydrogen sulphide: G. E. F. LUNDELL and H. B. KNOWLES. Published methods for the determination of iron and vanadium after reduction by hydrogen sul. phide ordinarily yield high values. A modified method which is sufficiently accurate for most purposes is presented, and a procedure for accurate analysis is outlined.
The free energy of dilution of hydrobromic acid; the activities of its ions in very dilute and con
centrated solutions : MILLER SPENCER and ALBERT YOUTZ. The authors, in searching for definite G. LOOMIS.
evidence of depolarization in the electrolytic haloThe ultra-violet arc spectrum of yttrium: L. F.
genation of organic compounds, found that either YNTEMA and B. S. HOPKINS. The ultra-violet arc
slow reaction rate or slow diffusion, or both, prespectrum of Y was measured, using the yttrium
vented any marked depolarization Experiments oxide prepared by one of us for the determination
on the oxidation of FeCl, in HCI gave surprisingly of the atomic weight value accepted by the Inter
accurate information as to the rate of diffusion national Committee. The spectrograph used is an
under a variety of conditions, and showed that autocollimating quartz prism machine manufac
without stirring there is a film of stationary liquid tured by Adam Hilger, of London. A current of
about 0.5 mm, thick through which diffusion must 4 amperes at an E.M.F. of 220 volts was passed
take place. This emphasizes the great importance between vertical copper electrodes, the lower of
of violent stirring and of the use of rapidly difwhich held the Y,0, in its crater. Several promi
fusing inorganic carriers to extend the sphere of nent lines, attributed to Y in the literature, were
the organic reaction from a surface to a volume. absent, and several new lines were measured. The Observations on the drying and swelling of gelaresults given are the mean of five determinations. tine gels: S. E. SHEPPARD and F. A. ELLIOTT. At
tention is drawn to the importance of capillarity On the viscosity of gelatin sols : ROBERT HERMAN BOGUE. Experiments were carried out upon
in the first phase of drying of jellies. It is shown
that this, in conjunction with factors depending gelatin sols to accurately determine the relation between viscosity and concentration. The data
upon the shape of the jelly, causes the formation have been applied to Hatschek's formula for the
of an exo-skeleton tending to conserve or increase
the original external surface extension. It is viscosity of emulsoids and the value A'/A, repre
chiefly due to this, rather than to any internal senting the volume occupied per unit weight of dispersed phase, was shown not to be constant
supermolecular structure, that dried jellies on re
swelling in water tend to return to their original with varying concentration, but to rise to a maxi
concentration, mum and thereafter regularly decline. A tentative explanation is presented based upon the effect
Note on the influence of silver salts in catalyzwhich increasing concentrations of dispersed phase
ing the decomposition of ammonium persulphate will have upon the surface tension of the disper
solutions: S. E. SHEPPARD and A, BALLARD. The sion medium. An empirical expression defining influence of silver salts in facilitating the decomthe departure of the values obtained under varying position of ammonium persulphate in solution, first conditions for Hatschek's constant is given.
observed by H, Marshall and J. Inglis, has been
confirmed, and quantitative data on the rate of The structure of molecules of water: IRVING
change in relation to the silver content obtained. LANGMUIR. Dennison has recently shown by X
Further developments of the hydrogen elecray crystal analysis that ice consists of molecules
trode: FELIX A. ELLIOTT. Two new forms of hyof the formula 1,0,. In view of our knowledge of the structure of atoms it is not possible to ac
drogen electrode were described representing prob
ably the limits of simplicity and ruggedness withcount for the existence of this molecule on the
out reducing accuracy and rapidity of operation. basis of quadrivalent oxygen atoms. If pairs of electrons (duplets) constitute the valence bond,
Especial attention has been given in designing there can be no such bond between the two oxygen
this new apparatus to reduce the internal resis
tance to the lowest possible value so that a less atoms. A structure for this molecule is therefore
sensitive and hence cheaper, simpler and portable proposed in which the four hydrogen nuclei bind
electrical measuring instrument might be used. the two oxygen atoms. The duplet held by each
Such an instrument was described, working on the hydrogen nucleus has one of its electrons in each
potentiometer principle and employing a pivot type of the oxygen octets, instead of the more usual ar
movement. Examples of results obtained with the rangement in which both electrons of a duplet
two types of apparatus indicate that potentials form part of the same octet.
are reproducible to about 0.1 my. The purification of helium by means of charcoal:
Note on silver soap gels: G. STAFFORD WHITBY. L. FINKELSTEIN.
It has been observed that the silver salts of the The importance of diffusion in organic electro- fatty acids are capable of giving reversible gels chemistry: ROBERT E. WILSON and MERRILL A. in a variety of organic liquids—particularly in the
homologs of benzene and in halogenated derivatives of benzene and its homologs. The silver salts form gels at a lower point in the series of saturated fatty acids than do the alkali-metal salts; gels being obtained with silver caproate. A number of regularities were discernible. The silver salts of the higher members of the saturated fatty acid series show a greater solvation capacity than those of the lower ones. None of the saturated fatty acid silver salts gave a gel in benzene; but silver oleate did. Speaking generally, in the case of solvents of the same general chemical character, the higher the boiling point of the solvent, the greater appeared to be the solvation capacity of a given salt, and the smaller the extent to which the gel from a given salt suffered syneresis.
Catalytic effect in the reaction between ketones and halogens in aqueous solutions: F. 0. RICE. The velocity constant of the reaction between acetone and bromine is independent of the bromine concentration and Lapworth (J. C. 8. Trans., 1904, p. 30) explained this by saying that the acetone slowly enolized and the addition of bromine and splitting off of hydrobromic acid were practically instantaneous. This is probably incorrect since higher ketones have the same velocity constant as acetone, and an explanation based on the radiation theory was offered. The reaction is accelerated by neutral salts contrary to Lapworth's statement.
The transference numbers of sulfuric acid by the concentration cell method: A. L. FERGUSON and W. G. FRANCE. A cell combination was used which permitted the measurement of all the required potentials from one set-up. The value obtained for the transference number for the anion in concentrations between M/10 and M/100 at 25° C. was .1868 +.0007. The method was shown to be highly reliable. In all of the calculations it was assumed that sulfuric acid dissociates into two hydrogen and one sulfate ion. This assumption was substantiated by the results obtained. A formula for boundary potential was developed in which boundary potential may be obtained from potential measurements alone.
The influence of gelatin on the transference numbers of sulfuric acid: ALFRED L. FERGUSON and W. G. FRANCE. The transference numbers were determined by the concentration cell method. Solutions of sulfuric acid containing from 0.5 per cent. to 20 per cent. gelatin were used. The transference numbers of the anion increased from .187 for pure acid to .685 for acid containing 20 per
cent. gelatin. In the 20 per cent. gelatin solution the boundary potential of both concentration cells became zero. The decrease in conductivity was approximately proportional to the gelatin added. The results are probably best explained on the assumption that there is a chemical action between the gelatin and sulfuric acid in which a single compound is formed. In this compound the hydrogen of the acid loses its identity and when the compound dissociates there is formed a complex gelatin hydrogen positive ion and a negative sulfate ion.
The entropy of monatomic gases: GILBERT N. LEWIS.
The electrometric titration of uranium with potassium dichromate and potassium permanganate: D. T. EWING and E, F. ELDRIDGE.
The heat of coagulation of ferric oxide hydrosol by electrolytes: FREDERICK L, BROWN and J. H. MATHEWS.
Some quantitative experiments on coagulation of colloids: RAY V. MURPHY and J. H. MATHEWS. The lowest concentration (limiting concentration) of electrolytes necessary to coagulate hydrous ferric oxide sol has been studied as a function of the purity of the sol (ratio of gram-equivalents of Fe to gram-equivalents of CI) and of the concentration of Fe,03. Chloride, chromate and ferricyanide ions were used in the form of the potassium salts. The conclusions drawn are: (1) The limiting concentration decreases with increasing purity in the case of all three ions, the mechanism of the process being evidently similar for the three ions; (2) The limiting concentration decreases markedly with decreasing concentration of the sol in the case of all three ions, but the relation indicated by Burton and Bishop, Jour. Phys. Chem., 24, 701 (1920), for mastic, As. Sa and Cu sols, holds for Fe,0, hydrosol only in the case of the trivalent ion.
The alkalinity of Searles Lake brine: ROGER C. WELLS. The title may mean either the titration alkalinity or the hydrogen ion concentrations. The latter may be considered as determined by certain proportions of the four buffer substances Na,CO2, NaHCO3, Na,B,O., and Na,B,0The writer has found for the brine Ph=9.48. By determining the Ph values of artificial brines containing each pair of buffers separately it is possible to draw curves from which by interpolation the proper proportions of the buffers to yield PH 9.48 may be read. This method serves as a check of the analyti
A 75 gm.
cal determinations and yields a logical conventional and gave the usual indications of a pure substance, form for expressing the whole analysis of the brine. such as constant freezing point for the first and
The vapor density of technical phosgene: A. F. last fractions of the liquid. The melting point O. GERMANN and VERNON JERSEY.
curve with BF, shows two massima, at 15 per cont. sample of technical phosgene was distilled from a BFs, and at 33 per cent. BF., and an angular large cylinder of the liquefied gas, obtained from point in the curve at 50 per cent. The form of the Chemical Warfare Service through Dr. Goss. the maxima at 15 per cent, is identical with that Pure phosgene has a vapor tension at 0° C. of at 50 per cent. for methyl ether; the mixture about 552 mm.; the sample taken showed a vapor yields about 15 per cent. of the total volume of a tension in excess of one atmosphere at - 80° C., biquid, whose freezing and boiling points are that is, in a bath of solid carbon dioxide and identical with those of BF,. (CH,),0. The logical acetone. The sample was subjected to fractional inference is that methyl chloride as prepared condistillation in a vacuum until the vapor tension at tains methyl ether as an impurity, and that this 0° C. was approximately correct. Following this, impurity yields a constant boiling mixture. It three fractional distillations alternated with three would seem that boron trifluoride might be used determinations of the vapor density of the gas, un- as a test for the presence of methyl ether in til five groups of three determinations each had methyl chloride; the same test might be extended been obtained for the vapor density, and the nearly to the homologues. The interpretation of the other pure gas had been fractionally distilled 15 times. maxima mentioned must await the completion of Average of 1st group of densities... 4.4708
further work on the purity of methyl chloride. .4.5060
The cryoscopy of phosgene solutions: 1. Sys.4.5216 .4.5244
tem with chlorine: A. F. 0. GERMANN and V.
..4.5263 JERSEY. The melting point curve of solutions of The values given are in grams per liter at
phosgene and chlorine was determined. The curve standard conditions, uncorrected for the compres
is very complex. There is a eutectic at 25 por sibility of the gas and for the contraction of the cent. (molecular percentages) chlorine; and anglobes when evacuated. Technical phosgene is
gular points in the curve at 6 per cent., 11 per very impure. The principal impurities are very
cent., 50 per cent., 63 per cent., 75 per cent. and volatile and of relatively low molecular weight,
91 per cent, chlorine. The following compounds, probably carbon dioxide and hydrogen chloride re
which dissociate at the melting point, are indisulting from hydrolysis. Repeated fractional dis
cated: 16C0C1. Cla; 8COCI. C1,; COCI.C; tillation yields a product whose density tonds 30001..5C1,; COC1.3c1,; and COC1,.10C1, The toward a maximum value, probably the value for second of these, chlorine octaphosgenate, is particupure phosgene.
larly interesting, as corresponding with the octaThe cryoscopy of boron trifluoride solutions: V. hydrate of chlorine. The affinity of chlorine for Systems with methyl ether and with methyl chlo.
phosgene, and the instability of the compounds ride: A, F. O. GERMANN and MARION CLEAVELAND.
would seem to offer an explanation of the mechGasselin prepared the compound BF,. (CH,),0 by
anism of certain phases of the catalysis of carbon mixing the gases; he obtained a liquid boiling at
monoxide and chlorine by means of charcoal sat126° C. This compound has been prepared from
urated with chlorine. If we assume a layer of liquid boron trifluoride and liquid methyl ether
chlorine molecules on the surface of the charcoal, in the course of the determination of the melting the high concentration of chlorine thus obtained point curve of solutions of the two substances. might be supposed in the presence of carbon monThe curve shows a eutectic at 3 per cent. BF, oxide to shift the equilibrium in the direction of (molecular percentages) and a maximum at 50 one of the chlorine-phosgene complexes, which per cent. The vapor tensions of solutions contain- promptly decomposes because of its instability, ing from 60 per cent. to 90 per cent. BF, were 80
leaving the surface film of chlorine for further high, that the form of apparatus used was inade
action. It would be desirable to determine the quate. The form of the curve so far as determined melting point curve of carbon monoxide and chloseems to indicate the existence of a second com
rine solutions, to clear up some of the points inpound in this interval. Methyl chloride was pre
volved in this reaction. pared from salt, sulfuric acid and wood alcohol;
CHARLES L. PARSONS, was purified by repeated fractional distillations;
Johns Hopkins University Tulane University of
SCHOOL OF MEDICINE Candidates for admission must be graduates of approved colleges or scientific schools with at least two year's instruction, including laboratory work, in Chemistry, and one year each in
(Establishod in 1834) physics and biology, together with evidence of a reading knowl- ADMISSION: All students entering the Freshman edge of French and German.
Each class is limited to 90 students, men and women being Class will be required to present credits for two admitted on the same terms. Except in unusual circumstances, years of college work, which must include applications for admission will not be considered after July 1th
Chemistry (General and Organic), Physics and If vacancies occur, students from other institutions desiring advanced standing may be admitted to the second or third year Biology, with their laboratories, and at least provided they fulfill all of our requirements and present es. one year in English and one year in a modern coptional qualifications.
foreign language. INSTRUCTION
COMBINED COURSES: Premedical course of two The academic year begins the Tuesday Dearest October 1 and closes the third Tuesday in June. The course of instructon,
years is offered in the College of Arts and pocuples four years and especial emphasis is laid upon praca
Sciences, which provides for systematic work Hical work in the laboratories, in the wards of the Hospital and leading to the B.S. degree at the end of the in the Dispensary. TUITION
second year in the medical course. The charge for taition is $250 per annum, payable in throo instalments. There are no extra fees except for rental of microscope, cortain expensive supplies, and laboratory breakage.
School of Pharmacy, School of Dentistry and The annual announcement and application blanks may be Graduate School of Medicine also. obtained by addressing the Dean of the Johns Hopklas Medical School
Women admitted to all Schools of the Washington and Monument Sts. BALTIMORE, MD
College of Medicine
For bulletins and all other information, address Beginning Tuesday, June 6th, and ending Thursday, July 16th, a course in medical diagnosis, including laboratory exer
Tulane College of Medicine cises in clinical pathology and demonstrations in pathological
P.O. Box 770 anatomy, will be offered The course will be limited to hoenty students, fee $100. Applications should be made to the Dean'
New Orleans, La. Office.