digestive juices, but that all actions of the individual are affected by the particular surrounding conditions of such actions.

That unfortunate effects result from the failure to appreciate the fact that in dealing with the human organism we are not dealing with isolated elements is a common observation in medical practise. All too frequently an individual, who is clearly in the process of preventable disintegraton, is caused to break down completely because the elemental theory actuates the psychiatrist to pronounce that there is nothing wrong with a person having no apparent organic or functional lesion. The writer wishes to suggest, that at least from a medical standpoint, we have placed too great emphasis upon the chemical factors in the process of human digestion and too little stress upon the psychological factors.

UNIVERSITY OF CHICAGO

J. R. KANTOR

A SIDEWALK MIRAGE

TO THE EDITOR OF SCIENCE: It seems the phenomenon here described must have been noticed by many others, but it caught my attention for the first time about two weeks since, and nowhere have I seen it described. On several occasions, lately, I have observed a mirage under the conditions hereafter stated which are those of a typical case. I was walking eastward on a cement sidewalk on a street running nearly east and west, and moving up a moderate grade which joins a nearly level stretch of walk. On reaching a point which brought my eye slightly above the level portion, and at which normally the level stretch would have been seen in its entire length, but much foreshortened, I observed instead what appeared to be a stretch of clear dark water covering the entire width of the walk, and brilliantly reflecting moving persons and other objects in sight beyond it.

The sky was clear, the air cool, the sun high. It was about three o'clock P.M., local time. There was a moderate breeze. The angle of observation was very small, probably not above three degrees. A step or two either east or west, and the water was gone,

Helmets and Body Armor in Modern Warfare. By BASHFORD DEAN. New Haven, Yale University Press.

To most of us armor belongs to the romantic past. We hardly think of it as a practical, up-to-date accessory of modern warfare. But in a book which has recently appeared, it is clearly demonstrated that armor has still a distinct value. We are of course familiar with the various steel helmets used by all the nations in the Great War, but it is not generally known that all the countries were hard at work experimenting with and developing body armor of every sort for their fighting General Pershing recognized its value and in the title page of Dr. Bashford Dean's "Helmets and Body Armor in Modern Warfare" he is quoted as saying that "effort should be continued towards a satisfactory form of body armor."

men.

Dr. Dean is the foremost authority on armor in this country and curator of arms at the Metropolitan Museum of Art. When we entered the war he was placed in charge of the armor problem and his tireless energy and enthusiasm, together with the generous cooperation of the Metropolitan Museum, led to the development of many types of armor for our combat troops. It is unfortunate that too little of this armor was used during the final drive of 1918.

Dr. Dean views the subject from many angles. The introduction is devoted to the evolution of modern armor from early times and enables one to contrast the old with the new. The medical viewpoint is considered

with statistics showing the frequency of wounds in certain locations and its bearing on the armor problem.

The utilitarian side is shown and the advantages and disadvantages are carefully weighed. Of interest to metallurgists are tables showing the ballistic values of various metals used for armor and one interesting chapter is devoted to the subject of "yielding" armor, such as padded cotton and silk fiber. Indeed the matter is viewed both from a distance and in minute detail.

The experimental types of armor of all countries are shown and reasons given for their success or failure.

Dr. Dean's summary and conclusions are of particular interest. He believes that we have not as yet solved the problem of providing the best alloy for armor and that the end, as far as the improvement of thin plate for ballistic use, is not yet in sight.

The old struggle between bullet-proof armor and armor-piercing bullets is still on, although at the present time the armor seems to have the advantage.

The question of the best form of the American helmet is also considered. At present we are still using the British helmet and American experts agree that this model does not give sufficient protection to the back and sides of the head. Moreover, a national type should be adopted.

The question as to whether armor will be used in the future hinges not a little on the problem of getting transports to the front. The infantry-man carries a maximum necessary load without his armor which would therefore have to be sent up to him.

Considerable prejudice among the men also accounts for the unpopularity of armor-they do not wish to be burdened with it and would rather take the chances on being hit. But as the author puts it, if they can be made to see that it is really worth while, this prejudice may be overcome.

Dr. Dean, from his careful study of ancient armor and his practical knowledge of modern conditions, is qualified to speak with authority on the subject. In designing the modern hel

mets, a comparative study was made of the more ancient ones in the Armor Hall of the Metropolitan Museum of Art. Diagrams showing the development of armor were used and every type of helmet used with success in the past was carefully studied. If it seemed practical, a modern adaptation was designed and beaten out by hand. Due allowance was made in the design for its eventually being pressed out in millions by modern machinery. By this common-sense method Dr. Dean was able, in a comparatively short time, to weed out the impractical forms and to develop a modern type of armor made by machinery for modern warfare. Who can say, but what it may not yet be used?

DWIGHT FRANKLIN

SPECIAL ARTICLES

DECOMPOSITION OF HYDROGEN PEROXIDE BY ORGANIC COMPOUNDS AND ITS BEARING ON THE CATALASE REACTION

THE last few years have witnessed a revival of unusual interest in the oxidizing enzymes and more particularly in catalase. The catalase reaction derives its interest from the fact that according to recent interpretations it is supposed to be a measure of the metabolic function of living matter. This view, entertained some twenty-odd years ago by Spitzer,1 has been given much currency in late years by Burge whose numerous contributions to this topic are well known.

Considering the process of intracellular oxidation which is still very obscure it is possible to recognize three factors or enzymes involved in some way or other in the reaction. Of these the oxidases affect the oxidation of easily oxidizable substances directly; the peroxidases accomplish this indirectly by activating part of the oxygen of peroxides; lastly, the catalases by decomposing peroxides liberate inactive or molecular oxygen. It was in this sense that Loew employed the designation "catalase" for the enzyme which may ultimately turn out to have no relation to the

1 Spitzer, Arch. ges. Physiol., 67, 615–656, 1897. 2 Loew, Report 68, U. S. Department of Agriculture, 1901.

oxidation of organic substances. The occurrence of catalase is so general in plant and animal tissues that its existence certainly must have a significance. Loew conceived the idea that peroxides are formed in the cells in the process of respiration, and that the catalase saves the protoplasm from being injured by these peroxides by decomposing them as fast as they are being formed. Usher and Priestly have shown that in plants at any rate hydrogen peroxide is actually one of the substances formed under the action of light and, if not immediately destroyed by catalase, will bleach the chlorophyl and thus interfere with the photosynthetic reaction. In the last few years the work of Appleman, Zaleski and Rosenberg, Loevenhart and Kastle, Alvarez and Starkweather, McArthur and notably of Burge have drawn attention to the probable function of catalase as an index of metabolic activity. Our interest in catalase originated with this fundamental problem of the relation of catalase to tissue metabolism. It may be mentioned that since our research has been in progress a number of papers appeared by Becht, Stehle," Reimann and Becher which not merely challenge the interpretation which Burge and others place on catalases, but also their experimental findings.

The observations of which this is a preliminary report, although not bearing directly upon the fundamental problem of the catalase function, throw nevertheless interesting light on the subject. The literature contains many instances of inorganic substances, such as colloidal platinum and several others which possess remarkable catalytic power, and bring about reactions characteristic of enzymes. Thus Sjolleman' found that colloidal manganous oxide gives all the typical reactions for oxidases. Again Wolffs showed that certain

3 Usher and Priestly, Proc. Roy. Soc. London, 77B, 369, 1906.

4 Becht, Am. J. Physiol., 48, 171–191, 1919.

5 Stehle, J. Biol. Chem., 39, 403, 1919.

• Reimann and Becker, Am. J. Physiol., 50, 54, 1919.

7 Sjolleman, Chem. Weeklad, 6, 287-294, 1909. 8 Wolff, C. r. Ac. Sc., 146, 142-144, 781-783, 1908.

iron salts can play the part of peroxidases, while Bredig's "inorganic ferment"-a colloidal platinum-is capable of decomposing hydrogen peroxide as vigorously as catalase. There is, however, no record of organic substances simulating a biological process. We have discovered a group of aromatic hydrocarbons and their derivatives which give the typical catalase reaction. Such substances may undoubtedly help to throw light on the chemical structure and characteristics of the enzyme itself.

Our numerous experiments which we will report in detail later arose from the accidental observation that an enzyme preparation preserved with toluol had acquired a remarkably increased capacity for decomposing hydrogen peroxide. It was at that time also that a paper appeared by Euler and Blix1o on yeast catalase in which these authors state that the catalase is activated by several substances, toluol among them. The idea of an activation of the enzyme by toluol seemed entirely improbable from our experience, because we found that even such minute quantities of toluol as 0.05 or 0.1 ccm. can decompose hydrogen peroxide. We undertook therefore to examine a number of related organic compounds in the hope of finding whether this non specific catalase reaction is in any way associated with the chemical structure of the organic catalysts. Starting with benzene we studied a number of its homologues and some of its derivatives. Benzene was found to react most vigorously, 0.2 ccm. liberating about 20 ccm. of oxygen from hydrogen peroxide in a manner so closely resembling the effect of an active enzyme preparation that one could not tell the difference unless informed as to the material used in the test.

The aromatic hydrocarbons of the benzene group form a series according to the number of methyl radicles attached to the ring with a gradually decreasing power to decompose hydrogen peroxide, thus:

Benzene > Toluol>Xylol>Mesitylene

9 Bredig, "Anorganische Fermente,'' 1901. 10 Euler und Blix, Ztschr. physiol. Chem., 105, 83-114, 1919.

The reaction is not general for the aromatic hydrocarbons, but is specific for those of the benzene series. Hydrocarbons with more than one benzene ring, like diphenyl and triphenyl methane, benzidine, naphthalene and anthracene all proved to be inert. Heterocyclic compounds also gave negative results.

We mentioned already that the increase in the number of methyl groups in the benzene ring results in a corresponding decrease of the catalytic activity of the compound. The introduction into the ring of a carboxyl group, an NHNH, group or of phenol groups renders the hydrocarbon incapable of decomposing hydrogen peroxide. On the other hand, the presence of nitro, amino and aldehyde groups, or of a halogen atom does not prevent the

compound from breaking up of hydrogen peroxide, though its power is much less than that of the unsubstituted hydrocarbon. Aniline, nitrobenzene, benzaldehyde and chlorbenzene decompose hydrogen peroxide, but dichlorbenzene, benzylchloride or benzoylchloride, were found inactive. Adrenalin, both the base and the hydrochloride, decompose hydrogen peroxide though very feebly.

A more detailed discussion of the catalaselike reaction of benzene and its homologues is reserved for the near future. Suffice it to say that we have satisfied ourselves that this decomposition is not caused by changes in surface tension. SERGIUS MORGULIS, VICTOR E. LEVINE

CREIGHTON MEDICAL COLLEGE

A SIMPLE DEVICE FOR SHOWING BY A
HYDRAULIC ANALOGUE THE EFFECT
PRODUCED ON THE POTENTIAL

DIFFERENCE BETWEEN THE
TERMINALS OF AN ELEC-

TRIC CELL WHEN THE
CIRCUIT IS CLOSED

THE Lodge theoretical paddle wheel device shown by Professor Kimball in Figs. 336 and 337 of his "College Physics" (ed. 1917) suggested to the writer an arrangement which would render possible an actual lecture demonstration.

66

Into the glass U-tube of Fig. 1 a stream of water is injected at P. The water is removed at the exits E and E', the sizes of which may be controlled by adjustable pinchcocks C and C' on the rubber tubes T and T'. The current" is controlled by the pinchcock C" or one's fingers on the rubber tube T." The inflow at I may be controlled by the faucet to which the apparatus is attached. When C" is closed, h represents the potential difference on open circuit. Upon opening C," level B falls and A rises: h'<h or the potential difference decreases when the circuit is closed.

My friend, Professor F. A. Saunders, has modified the arrangement by placing the water-spout at P' (Fig 2). This is an improvement from the pedagogic standpoint as the source of gross energy in an electric cell lies at the surface of separation between one plate and the electrolyte. He also suggests removing the injected water at but one point, E" (Fig. 2).

PHYSICAL LABORATORY, BOSTON UNIVERSITY

NORTON A. KENT

THE AMERICAN METEOROLOGICAL

SOCIETY

THE second meeting of the American Meteorological Society was held at the Weather Bureau, Washington, D. C., on, April 22, 1920. The attendance was 40 to 50 at each of the two sessions, held in the morning and in the evening. Professor C. F. Marvin, chief of the U. S. Weather Bureau gave a short address of welcome, which was followed by a program of 15 papers. Brief

synopses of the papers and discussions were published in the society's bulletin for May, 1920 (pp. 48-55); and the papers themselves or authors' abstracts are still appearing in the Monthly Weather Review (issue shown in parentheses). The program was as follows:

*Temperature scales and thermometer scales: E. W. WOOLARD. (May.)

Shall we adopt a half-degree absolute centigrade scale instead of the Fahrenheit? CHARLES F. MARVIN. (Not published.)

The physics of the aurora: W. J. HUMPHREYS. (Abstract to be published.)

*The auroras of March 22-25, 1920: HERBERT LYMAN. (July (1).)

The most intense rainfall on record: B. C. KADEL. (May.)

*New aerological apparatus: S. P. FERGUSON. (June.)

Temperatures versus pressures as determinants of

winds aloft: W. R. GREGG. (Abstract, May.) *Daily wind charts for stated levels: C. LEROY MEISINGER. (May.)

Cloud base altitudes as shown by disappearance of balloons and kites: O. L. LEWIS. (July (1).) *Cloud nomenclature: CHARLES F. BROOKS. (July (1).)

*Some meteorological observations of a bombing pilot in France: THOMAS R. REED. (April.) Project for local forecast studies: R. H. WEIGHTMAN. (March.) (By title.)

Climatic conditions in a greenhouse as measured

by plant growth: EARL S. JOHNSTON. (Abstract, April.)

Modifying factors in effective temperature: ANDREW D. HOPKINS. (April.)

Relation of rainfall to the grazing capacity of ranges: J. WARREN SMITH. (June.)

Separates have been or are to be made of those starred, and may be obtained from the U. S. Weather Bureau, Washington, D. C.

The American Meteorological Society, the project of which was announced in SCIENCE, just a year ago (August 22, 1919, pp. 180-181), and of which progress was reported (December 12, 1919, pp. 546547) and organization in December announced (March 12, 1920, pp. 275–276), has grown with unexpected rapidity to a membership of nearly 1,000. Plans are being made for the organization of a Brazilian division of the society, and it is probable that a Pacific division will be organized when the Pacific section of the American Association for the Advancement of Science meets next summer.