cess.

Inoculations of the pure culture into healthy peonies, however, readily produced infections, and the characteristic "blighted" symptoms, from which the organism was reisolated with ease.

Inoculations were made

upon plants growing out doors with pure culture, using bits of mycelium and zoosporangia, and were successful both with and without wounding of the host. The characteristic symptoms appeared in from three to six days. The Phytophthora in question grows readily upon a variety of artificial media, and in this respect differs from P. infestans. The growth is somewhat sparse upon the surface of agar slants, but is abundant beneath the surface.

It has been grown on ordinary beef peptone agar, potato agar, corn meal agar and in beef broth, where it grows luxuriantly submerged but not at the surface. Zoosporangia are produced in abundance and measure 16.722.3 μ x 20.4-29.7 μ. These measurements correspond closely to those for the zoosporangia of P. infestans1 but are somewhat broader than those of P. Thalictri2 which would appear to be its closest relative so far as hosts are concerned. Oospores have not been observed either in cultures or tissue sections.

H. W. THURSTON, JR. C. R. ORTON

PENNSYLVANIA STATE COLLEGE

1 Rosenbaum, J., Jour. Agr. Res., 8: 233-276. 1917.

2 Wilson, G. W., Bull. Torr. Club, 34: 387-416. 1907.

QUOTATIONS

FAIR WEATHER PREDICTIONS

171

ONE fixed determination in the office of this Journal has been that the monthly issue shall always be ready to go into the mails on the appointed date. The staff has loyally cooperated in this effort, regardless of hours of work. With the notice given in April of an impending strike on the first of May, the matter passed beyond our hands, and when the strike materialized, the record of promptness was effectually shattered.

Fortunately for our peace of mind, the Council of the Society, representative of the membership, had agreed, by formal resolutions adopted at the Rochester Meeting, to wait indefinitely for journals, thereby materially assisting the printer in his stand against what he considered unjust demands from the striking employees.

The labor conditions affected most seriously the hand composition work in the printing office, and this force has been recruited on an open shop basis until it is now greater in number than before. Naturally, men not accustomed to printing chemical articles have had to be developed and trained, so that the new force, at first quite inefficient, is gaining steadily in efficiency. There is now every prospect that the August issue will quickly follow and that the September issue will go into the mails promptly on the last day of August. Pardon anachronisms in the editorials of the July and August issues, in view of the unusual situation.

With all of these troubles upon us, there has been one pleasurable aspect of the situation, the hearty cooperation of both authors and advertisers in the effort to get our work upon a right and permanent basis. Letters received, especially from advertisers, make us feel that there is a strong bond between this Journal and its patrons, and we desire here to express our sincere appreciation of that spirit.

One further word only to the authors of papers is added. The preparation of reprints requires a considerable amount of hand composition work and remaking of material. We

urge authors to be extra patient in the matter of receiving their reprints. If the present composition force is diverted to work on reprints, the issue of each of the journals of the society would be delayed to that extent. We have, therefore, taken the liberty of authorizing the printer to postpone the making up of reprints from this Journal, and to put all emphasis upon catching up with the regular schedule of publication. We are confident of an extension of loyal cooperation on the part of our contributors.

To adopt the language of the Weather Bu"For to-morrow: fair weather."-Journal of Industrial and Engineering Chemistry.

reau:

SPECIAL ARTICLES

NOTE ON THE USE OF THE DUBOSCQ TYPE OF
COLORIMETER FOR THE DEMONSTRA-
TION OF DIFFERENCES IN SUR-
FACE TENSION

ALTHOUGH there are many interesting experiments by which the phenomena of surface tension can be demonstrated to students, as a rule they fail to give a basis of direct visual evidence of the main force concerned. Consequently any procedure which will enable the student to demonstrate to himself in a semiquantitative manner, that there are differences in the ability of different liquids to sustain themselves by the forces inherent in their surfaces, should assist in an understanding of the underlying principles.

Such a demonstration can be staged by the use of the Duboscq type of colorimeter. Moreover the effects of the additions of minute amounts of various substances to water, on the surface tension of the latter can be strikingly shown.

If that point on the scale at which the dry lower surface of the plunger just comes in contact with the surface of a liquid in the cup or small beaker of about 5 cm. diameter resting upon the cup support is taken as the base line, it is possible to measure with a considerable degree of constancy the height in tenths of millimeters to which the plunger can be raised above the surface of the liquid before the clinging column of fluid breaks contact and slides back into the container. This

affords a clear idea of the principle of surface tension from the fact that an obviously weighable volume of liquid is lifted and held above the main surface of fluid by the force of the liquid surface in contact with the plunger.

When a comparison is made of the height to which the plunger can be raised from contact with the surface of such substances as water, ether, absolute alcohol, acetone and toluol, it becomes at once evident that different liquids have different abilities to cling to the plunger surface and hence different surface tensions. When a bit of soap is swished around in the water in the beaker and then removed, the marked decrease in surface force is made plain by the decrease in the height to which the plunger can be raised before contact is broken. A similar result is obtained when a trace of amyl alcohol is added to the water. When a bit of picric acid is dissolved in the water in the beaker the opposite effect is observed and is of sufficient magnitude to demonstrate why picric acid solutions "bump" when heated.

36

33

Water plus soap..

Water plus amyl alcohol.
Water plus picric acid........ 42

The accompanying table shows the values obtained for the substances mentioned. The second column of figures gives the values for the same compounds as copied from Landolt, Bernstein and Roth's tables, 4th edition, in terms of a❜mm2. The correspondence is pleasingly close, but is of course accidental since contributing factors other than the height in millimeters are obviously involved, though in this group they happen to be mutually compensating.

These few examples suggest the availability of the plunger-cup mechanism as a basis for the development of an accurately calibrated piece of apparatus for the determination of

absolute surface tension values in terms of dynes. Such an instrument with its proper formula might well be of service in such measurements because of its simplicity of manipulation.

FREDERICK S. HAMMETT

THE WISTAR INSTITUTE OF ANATOMY AND BIOLOGY

VARIATION OF INDIVIDUAL PIGS IN ECONOMY OF GAIN

IN a very interesting article by Ashby and Malcomson, published in the Journal of Agricultural Research, Volume XIX., pages 225234, the following statement is made on page 232:

The resultant coefficient of correlation

0.452 ± 0.068

shows a distinct negative correlation between rate of gain and economy of gain, entirely disproving the apparent relation shown by Tables IX. to XV.

This conclusion is very interesting, especially since it is contrary to the usual belief and usual experience. The writer has recalculated the coefficient of correlation from Table XVI. on page 232 and found a different result from that given by Ashby and Malcomson in that r—— -0.1660.083 which is not a significant correlation.

Thinking that a different treatment of the data might throw further light on this point, a new correlation table was made between the rate of daily gain and the amount of feed required to produce 100 pounds of gain. correlation was found to be

↑= +0.140±0.083.

This

This is not a significant correlation, but it is interesting to note that it is positive instead of negative.

Again Ashby and Malcomson combined cases of animals fed on pasture and of those fed in the dry lot. From a statistical point of view, this is not advisable, since the food derived from the pasture was not taken into consideration.

The average daily gain of 27 animals fed on pasture was 1.14 pounds and the average amount of feed required to produce 100 pounds

of gain was 361.2 pounds. The average daily gain of 36 animals fed in the dry lot was 1.41 pounds and 391.8 pounds of feed were required to produce 100 pounds of gain. It is readily seen from these figures that the rate of gain among pasture fed animals was less than among those of the dry lot, and at the same time the amount of feed for 100 pounds of gain was less, because the part of the feed from the pasture was not taken into consideration.

Separate correlations were found for these two groups. In the pasture-fed group 0.181 0.126, while in the dry lot group -0.036±0.112.

Both of these are negative but not significant. When treated together

r=+0.140 ± 0.083,

a positive correlation but still not significant. One can not accept the conclusion of Ashby and Malcomson that there is a negative correlation between the rate of gain and economy of gain for the following reasons:

1. On the basis of their own data, there is no significant correlation.

2. From a statistical standpoint it is not legitimate to pool cases of animals fed on pasture and animals fed in the dry lot, for the purpose of determining the correlation between rate of gain and economy of gain since the two groups are dissimilar.

Other factors which might influence the results are initial weight, age, length of feeding period and methods of feeding. In their discussion, the possibility is suggested of using these individual differences as a basis for selecting strains which are more economical producers. But these variations which they found can not be said to be genetic because of too many uncontrolled factors such as cited above. It is interesting to note that even when pigs are self-fed, selection is exercised by individual pigs in the kinds of feed which they consume. The following table taken from a preliminary report by Ashby on page 201 of the 1916 Proceedings of the

DIVISION OF RUBBER CHEMISTRY

W. W. Evans, chairman.
Arnold H. Smith, secretary.

The day was devoted entirely to a discussion of the tentative procedure for the analysis of rubber goods.

Reports from the executive committee, abstract committee, accelerator committee, and physical testing committee were read.

Thermal conductivity of some rubber compounds: A. A. SOMERVILLE. Rubber mixes have been made containing different amounts of sulphur, with and without accelerators, with equivalent volumes of various fillers, and given a range of cures. The thermal conductivities of these samples have been compared and the results of the test indicate a wide variation in thermal conductivities due to different fillers being used.

Contribution to the knowledge of the resins of Hevea rubber: G. STAFFORD WHITBY and J. DOLID. A number of crystalline substances have been isolated from the acetone extract of plantation Hevea rubber. At least two of these are sterols. The less soluble of the two constitutes roughly 5 per cent. of the extract, it decomposes without melting, and forms an optically active acetate crystallizing in leaflets and melting at 169°. With this sterol another substance, not yet isolated in a state of purity, was associated. The soluble sterol consisted of matted, flexible leaflets, melting at 127°. A substance, optically inactive, melting at

62°, constituting roughly 5 per cent. of the extract, was obtained. Quebrachitol was isolated from the extract, and was found to occur generally in sheet and crepe. The results of a quantitative study of the oxidation of caoutchouc under the catalytic influence of copper are reported.

The solubility of gases in rubber as affecting their permeability: CHARLES S. VENABLE and TYLER FUWA. It was found that when rubber absorbs gas, the gas is held in true solution and not by absorption. In the case of carbon dioxide, which has about an average solubility, the amount of gas thus held in true solution by the rubber is directly proportional to the pressure and decreases with increasing temperature. This solubility is unaffected by degree of vulcanization or by the presence of compounding ingredients. Other gases seem to behave in a similar manner. Relative solubility values obtained for various gases in rubber show that there is a general relationship between the solubility and density of the gas and its rate of penetration through rubber. These results, in general, confirm the original hypothesis of Graham that the penetration mechanism consists in the solution of the gas at one surface of the rubber and the diffusion of the undissolved gas through the rubber and its evaporation at the other surface. The indications are, however, that the actual size of the gas molecule is also an appreciable factor. A striking relationship between the solubility of various gases in rubber and in water has been noted.

Reactions of accelerators during vulcanization, III. Carbo-sulphydryl accelerators and the action of zinc oxide: C. W. BEDFORD and L. B. SEBRELL. Reactions of accelerators producing mercapto groups by action of sulfur are discussed. Thio carbanilide with aniline in benzol solution will dissolve zinc oxide and will vulcanize a zinc oxide cement at room temperature. Other zinc salts of mercaptans such as zinc thiophenol and zinc-ethylxanthate will vulcanize pure gum cements containing sulfur at room temperature. These accelerators are free from nitrogen or alkali and also function in press or steam cures. Without zinc oxide no accelerator has been found which will vulcanize at room temperature. Zinc salts of carbo-sulphydryl accelerators furnish the key to the paper.

The influence of piperidine-piperidyl-dithiocarbamate on vulcanization: G. STAFFORD WHITBY and O. J. WALKER. Tested in a 90: 10 rubbersulfur mix, 1 per cent. of the base mentioned is

found to reduce the time of cure by seven eighths, and even at 130° to lead to curing in about one third of the time required at 141° in its absence. At the optimum cure rubber containing the base showed (a) a noticeably lower sulfur coefficient, (b) a very considerably higher breaking stress, (c) a noticeably smaller elongation, and (d) a lower position of the stress-strain curve (strains as ordinates) than did rubber from which the base was absent. On aging for 7 months, vulcanizates prepared with the base behaved in a manner essentially similar to that shown by vulcanizates prepared without it; the stress-strain curves coming down the paper to a similar extent and the breaking points altering in a similar way.

A rapid bomb method for the determination of sulfur in rubber compounds: W. W. EVANS and RUTH E. MERLING.

The direct determination of the sulfur of vulcanization: S. COLLIER and MICHAEL LEVIN. The sulphur actually combined with the rubber is determined by dissolving the rubber and polyprene sulphide in cymene. The solution is diluted with petroleum ether and filtered after the fillers have settled out. The filtrate containing the polyprene sulphide is evaporated to dryness by heating on the steam bath and by means of a gentle current of air. The residue is dissolved in nitric acid and the solution evaporated to dryness. Three c.c. of nitric acid are added to the residue and then 5 grams of sodium carbonate. The mixture is fused and the amount of sulphur determined.

Volume increase of compounded rubber under strain. (Lantern.) (With comments on the work of H. F. Schippel.): HENRY GREEN.

A general round table discussion followed on the topics of factory control of vulcanization, testing of crude rubber as received at the factory, reactions between sulfur and various softeners, and others.

DIVISION OF BIOLOGICAL CHEMISTRY

A. W. Dox, chairman.
H. B. Lewis, secretary.

A study of the highly unsaturated fatty acids occurring in fish oils: G. D. BEAL and J. B. BROWN. A proximate determination of the composition of five commercial fish oils was made by converting a kilo of each of the oils into its methyl esters by a modified Haller methanolysis, distilling these into ten-degree fractions under

reduced pressure and analyzing these fractions. Evidence for the presence of myristic, palmitic and clupanodonic acids was given, and also for acids more highly unsaturated and of greater molecular weight than clupanodonic acid. When the refractive indices of the fractions were plotted against the corresponding iodine numbers and mean molecular weights of the acids, curves which were nearly straight lines were produced. The analytical data showed a decided similarity for the oils examined, which included salmon, menhaden, herring, cod and sardine oils. The pure highly unsaturated acids were prepared in more than 50 per cent. yield by reduction of their methyl ester polybromides in methyl alcohol with zinc dust. The mean molecular weight of these acids by titration was over three hundred, a value Distillamuch too high for clupanodonic acid. tion of the methyl esters of these acids and analysis of the fractions gave good evidence for the presence of the following acids-hexadecatrienoic, CHO, clupanodonic, CH2O2, arachidonic, CHO, eicosapentenoic, C2H3O2, docosapentenoic, CHO, and docosahexenoic, C2H2O2.

Further studies on the mosaic disease of spinach: S. L. JODIDI. Mosaic disease affects many crops of vast economic importance such as the Irish potato, tobacco, corn, sugar beet, sugar cane, spinach, cabbage, lettuce, tomato, cucumber, and others. It seemed quite desirable to study the mosaic disease of at least one crop-in this case spinach-from various angles and by various methods. The results of the investigation have led to the following conclusions: (1) The physical and chemical properties of the soil taken from under diseased spinach plants were found to approach very closely those of the soil taken from under healthy plants. (2) The differences in the biological behavior of the two soils under consideration, as shown by their ability to ammonify various organic nitrogenous compounds, were so small as to be negligible. (3) The mosaic disease of spinach does not seem to be due to malnutrition, since in the experiments reported the diseased condition of the plants can not be ascribed to physical, chemical and biological conditions obtaining in the soil.

Chemical, physical and insecticidal studies of arsenicals: F. C. Cook and N. E. McINDOO.

Cysteine as a product of the intermediary metabolism of cystine: H. B. LEWIS and LUCIE E. ROOT. After the administration either orally or subcutaneously of 1-phenyluraminocystine to rabbits,