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NEW YORK, JULY 15, 1892.

THE CHEMISTRY OF SOILS.'

BY PROFESSOR R. ELLSWORTH CALL.

A SOMEWHAT extended experience in the chemical analysis of soils with a view to their agricultural value bas led to certain conclusions which may not be altogether devoid of value to the readers of Science. Especially may this be true since there is often an entirely erroneous opinion among those most concerned respecting the useful deductions which may be made from a complete chemical analy. sis of a soil. Usually it happens that if only the presence of certain desirable substances be shown, then the value of the soil for the production of this or that crop is assumed to be definitely settled. Nothing could, in general, be farther from the truth. Of course, something definite may be said of such soils as those in which both sand and clays, or either, predominate, but the conclusions in these cases are based on the physical characteristics of the soils rather than on their chemistry. Indeed, it is usual to classify soils in two general categories, the classification being based, on the one band, on the method of soil-formation, and, on the other hand, on its physical characteristics. The soils of Iowa belong, in tbe main, to that class which is based on the method of formation, and are composed chiefly of transported or drift materials. It is, however, true that the Iowa soils, though glacial, owe much to the physical characters of the rocks which they represent as disintegrated and far-travelled débris. The sands and clays are all transported materials, most of them from points many miles to the north of the prairie regions whicb they now cover. It is, moreover, clear that no degree of coarseness or of fineness, which may result from the methods of origination of any soil, constitutes in itself sufficient ground for saying this soil is fertile or tbat soil is unsuitable for plant growth. Recourse must be had to the ultimate composition of the sample, and right here enters an element of error against which, popularly, it is difficult to guard.

The physical character of a soil or marl must be considered when studied chemically. The finer the condition of the sample, in nature, the more readily are induced those changes in its chemistry which result from atmospheric influences. That is to say, when coarse and fine soils are treated alike mechanically by the plow, the one may become mellow and well mixed, while the other is broken without being well mixed or turned. Now, the chemical processes which occur are most active and most complete in soils that are fine in texture. It follows, therefore, that a stiff, clayey soil may contain all the essential elements of the food of any plant, but be in such condition physically as to render the chemical processes difficult of operation. And, on the other hand, such a soil may be sufficiently fine, but the well-known tendency to “cake" or harden on drying or exposure would render it valueless agriculturally, no matter how finely comminuted its materials may be.

1 Extracted from the Monthly Review Iowa Weather and Crop Service, Vol. III., No. 5, May, 1892.

Clayey soils, again, do not permit that free, subsoil circulation of water so necessary to growing crops. Circulation there is, but it is limited at best; open, porous soils admit free, underground water-flows, but such soils soon dry. They lose large quantities of water through evaporation, due to the rather free circulation of air in the upper portions of the cultivated areas.

Color, too, bas little to do with deciding finally whether a soil will be fertile. Usually all earths which are dark. colored or black-a condition largely due to the amount of carbonaceous material derived from decayed vegetation – are considered fertile. It is true that commoń consent places all such samples among the fertile soils, but it by no means follows as a necessary deduction. So, too, that light drab or ashy-colored soils lack the elements of fertility is a potion which observation and experiment alike negative. The most fertile of Iowa soils is the loess, a peculiar and very fine marl covering many hundred square miles along the Mississippi and Missouri rivers, as well as the higher lands along the Des Moines. It is a soil the color of which would condemn it for agricultural purposes, but it is one which is of exceptional value for all sorts of cereals, and is peculiarly adapted to the growth of fruit. It is finer in texture than is any other soil in the State. What, then, constitutes its peculiar feature, rendering it so valuable? The answer to the query lies almost solely in its physical condition, which is of a fineness equalling that of any clay. This fine condition renders it admirably suited to the action of native chemical agents. These are the real soil-makers. Soils that plants may use must be soluble, and one of the essentials to complete solubility is fineness of the constituent particles, A certain and definite relation to moisture must be established and maintained, a condition which is practically reached by under-draining soils of a clayey nature. Too much water will compel adhesion of the smaller particles, and the product thus formed be eventually coarse and lumps. Such a soil may be very fertile, but is not arable. This is the condition of most of the bottom lands of eastern Arkansas, the soils of which region are deficient in lime alone of all the ingredients which plants require. They are

wet and cold," and cannot be under-drained. Few soils of this nature occur in Iowa.

To make a long story short, chemical analysis of any given soil will determine its probable agricultural value only within very wide limits, and for reasons which appear below. It may be said, at this time, that such an analysis may determine one of two things, (a) the presence or absence of constituents which the plant must have, or (b) the presence of some substance which will affect injuriously a growing plant. The chemical laboratory will never supplant the province of carefully conducted experimental agriculture. But it may become a most valuable adjunct to the operations of the farm. The principles which underlie agricultural chemistry need only to be understood to be appreciated by those who have the manual labor of the farm to perform.

Aside from these general considerations there remain yet others to which it will be well to advert.

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One of the great difficulties in the way of an intimate needed in the compost he may apply. This borders on orknowledge of the relations of plants to soils lies in our ig- ganic chemistry and does not at present concern us. norance of the laws of assimilation in the plant.

The con

Among the substances which must be present in a soil to ditions under which the chemist studies these are of necessity give it an average degree of fertility stands pre-eminent the artificial. He cannot be assured that he has even measura- compound known as phosphoric acid. But this substance bly reproduced the conditions of nature, and hence cannot does not exist in the soil except in combination with some be sure that similar results will be attained under such most other substances, known technically as bases. These subnatural conditions. Those most complex and peculiar stances are commonly, if not always, iron and alumina, with changes which occur in chemical compounds under what, which they are in such chemical combination as to form for want of a better term, are denominated “ vital forces " salts known as phosphates. It is, however, not sufficient to can never, at least under the present limitations of knowl- know that these compounds are present. We must further edge, be fully understood. And right here is the gist of the know whether they are so associated with other compounds whole matter. A knowledge of the chemical constitution as to be readily disintegrated and rendered soluble, for un of a soil must precede a study of its relations to the full or less soluble they cannot be used as plant-food. Now, peither incomplete, as the case may be, development of a plant de- of these compounds of phosphoric acid — i.e., iron and alupendent on it for nourishment. In other words, the consti- mina phosphates -- is available in that form. Experiment tution of a soil is a determinable quantity, the life-processes has shown that the form in which these substances are availof the plant constitute an indeterminate quantity, and the able is that of calcium (lime) phosphate. That this has a relation of the two is the thing sought. No amount of relation to the amount of calcium silicate in the soil is chemical experimentation can bring into view the unknown clearly proven, and that by a process of double decomposifactor.

tion of the three compounds the available one is obtained is The various experiment stations which are now estab- also well known. But this process has not yet been cerlished in every State in the Union can do much toward tainly traced in nature. As stated at the beginning, it is clearing away a great cloud of agricultural superstition rel- right here that the processes of the laboratory and those of ative to these subjects. There should be place for the theo- nature need to be connected. Whether they ever will be retical as well as the practical in their work. It should be depends upon the support given to the great army of practiclearly shown that the constitution of a soil has far more to cal chemists whose attention is now directed to the theoretido with the growth of a crop of corn than the moon, or than cal features of agricultural chemistry. any other of the oft-quoted and still entertained notions of It should be a matter of congratulation to the farmers of strange and hidden forces. Tall oaks do not grow from Iowa that work along these lines is now progressing very little acorns except under the most favorable conditions of favorably at the experiment station at Ames. A vast soil, and these conditions, again, are affected by the innu- amount of valuable information may be expected from this merable changes which occur in temperature, moisture or source, and in due course of time it will come. other variables, which render more or less tractable the various compounds on which the plant must feed.

CURRENT NOTES ON ANTHROPOLOGY. – X. The chemist who studies a soil does so by the same meth

[Edited by D. G. Brinton, M.D., LL.D.) ods as those by which he would examine an unknown min

The Ancient Libyan Alphabet. eral, and usually with no greater care. He wishes, simply,

In Science, May 8, I called attention to the new light to know what elements may occur in it, under what condi

thrown upon the history of our alphabet in its ancient form tions, in what abundance, to what degree they may be dis

by the researches of Dr. Glaser among the ruined cities of sociated, and whether there be present any substance which

Arabia. Another curious study in the same line is that would interfere with their assimilation by the plant. In

offered by the Libyan alphabet. It appears to have been in this way he arrives at a fair knowledge of the sample, but be can tell you little of its value for agricultural purposes.

common use among the Berber tribes of North Africa long

before the foundation of Carthage, and is still employed He here depends not on his knowledge of soil constitution

constantly by the wild Touaregs of the Sahara. It is not or of its genesis, but on the facts of observation, which

the same as the Iberic alphabet of Spain, and in its forms is familiar to ezery farmer, and which he unconsciously con

almost entirely independent of the Phænician letters. It is nects as cause and effect. It does not need a chemist to tell

composed of consonants, called tifinar, and vowel-points, an observant farmer that he will not be likely to reap a

known as tiddebakin. The latter are simple dots, the forstrong growth of wheat from a sandbar. He bas bad as an

mer are the lives of a rectangle, more or less complete. instructor an experience in the relations of crops to the labor

Several of them are found in the oldest Etruscan inscriptions, expended on them that led him to definite and valuable con

and on that known as the “inscription of Lemnos." Sepulclusions on this matter. But there are innumerable ques

cbral epitaphs in this alphabet have been discovered dating tions which he may put to the chemist and hope for a profita

two or perhaps three centuries before the Christian era; ble answer. When once the soil has been exhausted of a

while rock-inscriptions of perhaps more ancient date, shownecessary constituent he may learn from experience that this

ing extremely archaic forms of the letters, have been copied or that material judiciously applied will remedy the defect.

from localities in the southern Atlas ranges. The farmer, moreover, has yet to learn that, even in Iowa,

The writers who have given especial attention to this littlethere cannot be a constant draft on a soil and the same crop

known subject are Faidherbe, Duveyrier, Halevy, Bissuel, be produced with equal value each year for an indetermi

and, recently, Dr. Collignon, who has a brief summary of nate number of years. Each crop lessens the productive

results in a late issue of Les Sciences Biologiques. power of a soil by the amount of material which it removes from the soil each season. Here it is possible for the chemist

The Aborigines of Asia Minor. to aid the producer by telling him exactly what bas been The artistic and linguistic studies into the proto-ethnology taken from the soil, and thus indirectly telling him what is of Asia Minor (see Science, May 20) are happily supplemented

are

by the investigations of Dr. F. von Luschan of Berlin, on by considerably over a million people, and it has made a the Tachtadschy of Lycia, published in the Archiv für An- deep impression on the Spanish of most of the Mexican and thropologie. This nomen gentile is not etbpic, but means Central American States. merely “wood-choppers," or "board-makers.” It is applied For Costa Rica, this has been shown in a work issued in to a sby, secluded people, who live in the mountains, and the present year at San José de Costa Rica, by Señor Juan fell and dress trees as their main business.

Fernandez Ferraz, formerly inspector-general of education On measuring them, Dr. von Luschan found that they in that republic. It is entitled, “Nabuatlismos de Costa had unusually short and high skulls, - hypsi-brachycephalic, Rica," and is a neat octavo of about 150 pages, with an intro- and were of small stature, with dark hair and eyes. Com- duction on Nahuatl grammar of 75 pages. The alphabetical parison with some skulls from very old Lycian graves, and list shows that a large number of terms in the current speech with part of the present population of Armenia and other of Costa Rica, which have assumed the form of Spanish portions of the region, led him to the conviction that in this words, are derived from the Mexican tongue. type so markedly distinct from that of the Greeks and A similar work for Nicaragua, written by the late Dr. C. Semites — he had before him the original of the most ancient H. Berendt, is now preparing for the press under the effipopulation of the land. He considers it certain that it ex- cient editorship of Dr. K. Lentzner of Berlin. The Nahuas, tended over the whole southern half of Asia Minor; north- or a colony of them, once occupied a considerable tract on east to the Caucasus; east to the upper Euphrates; but its Lake Nicaragua, and left the marks of their occupancy not northern and western limits are not yet defined. He even only in interesting ruins, but on the language of their conhints that the short, dark, brachycephalic people of central querors as well. It was in this Nahuatl-Spanish dialect that Europe may be the western extension of the type.

the comedy of Gueguence was written (published in PhilaAs to whence it came, be is not without an opinion. Not delphia, in 1883). from Europe, not from Africa, not from northern Asia, not It is agreeable to note in this connection that the study of from southern Asia; all are excluded for sufficient reasons; the Nahuatl finds zealous advocates in Mexico, among whom central Asia alone is left; and somewhere in that mysterious the names of Peñafiel, Palma, Hunt y Cortes, Altamirano, matrix gentium he expects will be found the ancestral con- Caballero, and Rosa, hold conspicuous places. nections of this well-marked type. There, then, we should

Anthropology at the Columbian Exposition. search for the linguistic analogies of the Cappadocian words quoted from Professor Tomaschek in my previous article. It

Anthropology does not appear by name at the Chicago

“World's Columbian Exposition.” This is to be regretted, would be a brilliant corroboration of a purely physical study

as it is a fine opportunity lost to inform the people of the in anthropology to discover such analogy.

United States what this grand science is, and how its several Work of the Eleventh Census Among the Indians.

branches stand related to each other. It is not generally known in fact, it is pretty hard to

It is represented, in fact, in “Department M," with a most

competent chief, Professor F. W. Putnam of Cambridge. A find out how much excellent anthropologic material is

descriptive pamphlet of this department which has just been annually collected and in part published by the various de

issued announces that it includes “ partments of our central government. The army, tbe navy,

Ethpology, Archæology,

History, Cartography, Latin-American Bureau, Collective the surgeon-general's bureau, the Smithsonian, the National Museum, and the specially created Bureau of Ethnology,

and Isolated Exbibits,”— rather a miscellaneous stock. It

is further stated that there will be a section on physical anall pour forth every year quantities of valuable observa

thropology and an anthropological laboratory, which are tions.

classified as a subdivision under the section of ethnology. Nor has the Eleventh Census been behind in this good

In spite of these defects in classification, no doubt abundant work, as is testified by the “Extra Census Bulletin,” just

and excellent material will be provided for the student, out, on the Six Nations of New York. It is but the fore

which he can work up in his own way. rupper of a series of such Bulletins on the remnants of our

A correspondent

in Berlin informs me that Dr. U. Jabn, who has charge of aboriginal population, and is an excellent earnest of the merits of its successors.

the matter there, has prepared, among other things, a series

of specimens of German houses of all varieties, to be erected The aim of these bulletins is to supply first-hand and ac

at Chicago, and in one of them, the rathhaus, he will arcurate statements of the present social, religious, industrial, vital, and political condition of the tribes; in other words,

range a complete exbibition of ancient and modern German

costumes, domestic utensils, home manufactures, etc. The they are ethnographic, in the right sense of the term. The general editor is Mr. Thomas Donaldson, and in this instance

sections at Chicago on Folk-Lore, Games, and Primitive Rehis collaborator is General Henry B. Carrington. A large ligions will be under the supervision of Stewart Culin Esq., quarto of 89 pages, well indexed, with maps and photographs,

of Philadelphia, who bas lately been appointed General Di

rector of the Museum of Archæology attached to the Unigives a most satisfactory account of the present status of the Cayugas, Mohawks, Oneidas, Onondagas, Senecas, and Tus

versity of Pennsylvania. The action of the Census Bureau in this direction is the more welcome, as in the rapidly changing condition

NOTES AND NEWS. of the native tribes, not many censuses will have the mate- VERY numerous experiments have been recorded to show that rial with which to occupy themselves in this direction. moisture is saved by cultivation. Frank E. Emery of the North

Carolina Experiment Station says: “During this bot, dry weather The Extension and Study of the Nahuatl Language erery foot of plowed land should be kept well stirred on the sur

face with any tool which tends to keep it from baking. A loose, If we may judge of the superiority of a language by its

fine surface will bold down water like a wet blanket. A field vitality; and by the impress it leaves on others with which

kept thus may give an increase in crop over one not cultivated it comes in contact, we must assign a high place to the equal to that produced by a heavy application of fertilizers. PreMexican or Nahuatl. It is still spoken in comparative purity servation of the soil-water thus becomes of great importance. A

caroras.

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blanket of fine soil on the surface during a hot, dry week can be of great value to the crop and really become the turning-point for profit if present wben loss might result from its absence.”

— The North Carolina Experiment Station has just published a 26-page Bulletin (No. 84) dealing with the fungous and insect enemies of garden and truck crops. The trucking interest has become one of the most important in the State. Good home gardens are not, however, so plentiful as they would be were it not for the ravages of insects and diseases. This Bulletin gives ten different formulas for compounding insecticides and fungicides, and explains the necessity for garden hygiene. The most approved forms of spraying apparatus are illustrated and described, and some trustworthy dealers in fungicidal chemicals are named. Everyone who has even a small garden is interested in the matters this Bulletin treats of. It is sent free to all residents of North Carolina, and will be sent as long as the supply lasts to residents of other States who send 6 cents in postage stamps. Address N. C. Experiment Station, Raleigh, N.C.

Dr. Arthur MacDonald, specialist in education as related to criminal and abnormal classes, United States Bureau of Education, Washington, D.C., has been appointed official representative of the United States to attend the international congress for experimental psyebology at London and also the international congress upon criminology at Brussels. The congress at Brussels will consider crime in its relation to biology and sociology. The congress is extremely cosmopolitan not only as to nationalities, but in the different departments of knowledge which it includes. The criminal must be studied as a member of the race, and this gives rise to the new science of criminal anthropology, or, in short, criminology. Here such questions will be discussed as to whether there is a criminal type distinguished by shape of cranium and face, anatomy of ears and nose, size of orbits and length of jaws. Another important question under this head is whether the criminal is born so or becomes so from his surroundings. In this division of the programme are the names of the celebrated Cesare Lombroso, professor of legal medicine at Turin, and Dr. Brovardel, president of the medical faculty at Paris, and Professor Ferri, senator at Rome. But the criminal must be studied psychologically, that is, as to the nature of his mind and will, and their relation to insanity and moral insanity. Among those who will speak in the congress on this phase of criminality are Dr. Magnan, chief physician of the Saint Ann Insane Asylum of Paris; Dr. Benedikt, the celebrated craniologist at the University of Vienna; and the brilliant French writer and legalist, Judge Tarde. Another and very important side of the criminal is included under the head of 'Criminal Sociology. This takes up crime in history and politics, the influence of profession and trade on criminality and their bearing in the determination of penalty. But there is a practical as well as a scientific point of view in the study of the criminal. This will be considered in the congress under the title of “Legal and Administrative Applications of Criminal Anthro. pology." Thus Dr Alimena of Naples will discuss what measures are applicable to incorrigible criminals. Then there are the general and fundamental principles of the school of criminal anthropology, wbich will be considered by Dimtri Drill of Moscow. Dr. Manouvrier, professor in the School of Anthropology at Paris, is to read a paper on the . Innateness and Heredity of Crime;" Dr. Bruxelles on “The Functional Causes of Crime;" Dr. Sernal on "Suicide and Insanity in Criminals.” The distinguished Lacassagne, professor at the University of Lyons, will speak on “ The Primordial Sentiments in Criminals." and Dr. Fioretti of Naples on “ The Applications of Anthropology to Civil Law.” Thus it will be seen that not only specialists in criminology, but those in medicine, insanity, law, psychology, anthropology, and sociology, all will consider the criminal from their respective points of view. The congress for experimental psychology represents the precedent tendency of applying scientific methods to study the relation between mind and body, or mind and brain, subjecta wbich are of as much interest and importance in the case of criminals as of normal men. This is illustrated by the new psycho-pbysical in. strument called the plethysmograpli, which indicates the least increase of blood in the arteries of the arm. Thus it has been

found, that when the sentence of the judge is read before the criminal, there is a decrease in the flow of blood in the arm, but the sight of a glass of wine increases the flow; when, for example, it is required to multiply nine times seventy-three an increase in blood flow is the result. The flow is little affected in a brutal murderer or born criminal, when a pistol is shown to him, whereas in the normal man the plethysmograph indicates a decided effect. The importance of this new instrument lies in this, that involuntary testimony is given as to the nervous and physical nature of the criminal. It is often unknown to him, and in spite of himself. Dr. MacDonald, after attending these congresses, will visit and study a few of the principal prisons and charitable institutions in England, France, Germany, Belgium, Switzerland, Austria, and Italy. A work of Dr. Macdonald's, entitled " Criminology," will soon be published by Funk & Wagnalls of New York. It is dedicated to Professor Lombroso, who writes the introduction and who himself is the founder of the new science.

A society which may have opportunities of doing much valuable work has been formed in Wellington, New Zealand, as we learn from Nature. It is called the Polynesian Society, “ Polynesia " being intended to include Australia, New Zealand, Melanesia, Micronesia, and Malaysia, as well as Polynesia proper. The president is Mr. H. G. Seth-Smith, chief judge of the native land court, while the Queen of Hawaii is patron. There has just appeared the first number of the society's Journal, in which there are papers on the races of the Philippines, by Elsdon Best; Maori deities, by W. L. Gudgeon; the Tahitian Hymn of Creation,” by S. P. Smith; Futuna, or Horne Island, and its people, by S. P. Smith; Polynesian causatives, by E T.; and the Polynesian bow, by E. Tregear. There is also a paper giving tbe genealogy of one of the chieftainesses of Rarotonga, by a native of Rarotonga. The original was written in 1857, and is printed in the Journal, with a translation by Mr. Henry Nicholas, and notes by the editors. The editors are of opinion that the paper apparently supports by direct traditional testimony the theory propounded by Hale, and subsequently advocated by Formander, of the occupation of the Fiji Group by the Polynesian race, and of their later migration eastward to Samoa and the Society Group."

The second annual meeting of The Mechanical Engineering Teachers' Association will be beld at Rochester, N.Y., beginning Aug. 18, 1892. This place and time of meeting is chosen as coincident with tbat of the American Association for the Advancement of Science in order to accommodate those who will wish to attend both meetings, and who may not be able to do so if at different times and places. The object of this association perbaps is best stated in Art. II. of its Rules, viz.: “To determine upon, and to secure by co-operation, the best courses of study, and the general adoption of methods of instruction, leading to the bighest efficiencs of schools of mechanical engineering.” The meeting last year was largely occupied with the organization of the association, so that comparatively little time could be devoted to the consideration of courses, methods, or appliances, either by reading of papers or discussion. But it is hoped that the Rochester meeting of this year will be productire of great good in crystallizing the views of the now quite large body of profcssors and teachers into such tangible and acceptable matters of opinion as to form a working basis for all. The following points are suggested as of importance for study by way of preparation for good work at the meeting, either in the presentation of papers, topical or general discussion, viz.: What subjects should be embraced in the course of mechanical engineering leading to graduation? Should any of them be optional ? Should there be a post-graduate course, and if so in what should it consist ? What should be the degrees for the above, and what the studies ? Should there be included one or two modern foreign languages ? What engineering studies should be included ? What amount of mechanical laboratory should there be included ? What subjects should be included in the mechanical laboratory? How much practice with the object of mechanical and manual training? How much fine mechanical practice such as scraping of surface plates, grinding of standards, etc.? Should the construction of articles of manufacture be at. tempted at the school laborators? What testing should be at

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tempted ? Should any part of the laboratory practice be classified as shop work, and so named, unless articles are made for sale ? Should anything be introduced that should be called “shop work?” Should that portion of the laboratory embracing the manual ele. ment be classified as “shop,” “school shop," “ work shop,” etc., or elementary mechanical laboratory? Should the more advanced portion embracing testing of various kinds be classified in such way as advanced mechanical laboratory, testing laboratory, etc.? It is further suggested that particular attention be given to the number of hours devoted to a subject, and the ground covered; the method of instruction, i.e., whether by lecture, recitation or practice, separately or combined. The address of the secretary is, A. J. Wiecbardt, South Bethlehem, Pa.

– The North Carolina Experiment Station has distributed a large quantity of broom-corn seed and instructions as to its cultivation to alliancemen and others, with a view to establishing it among the profitable crops in places well adapted for its best development. Close planting on fairly rich land is required for a good crop of brush fitted for making fine brooms. In order to better assist those who desire to learn all they can of this crop, and that all may have the benefit of as much information as possible on the subject of growing broom-corn and making brooms, the Experiment Station will engage to supply as many as wish a copy of “Broom-Corn and Brooms," a small book published by Orange Judd Co. of New York, at tbe wholesale price, with the postage added. The usual price is 50 cents. Send 30 cents in silver or stamps to the Experiment Station at Raleigh, if you wish a copy of this little book.

- A paper upon the oxidation of nitrogen by means of electric sparks is contributed, by Dr. V. Lepel, to the current number of the Annalen der Physik und Chemie. It is well known that small quantities of nitric and nitrous acids and their ammonium salts are produced during the passage of high-tension electrical discharges tbrough moist air. Dr. V. Lepel's experiments, according to Nature, have been conducted with the view of obtaining more precise information concerning the nature of the chemical reactions which occur, and the experimental conditions most favorable for increasing the amount of combination. The first action of the spark discharge appears to be the production of nitric oxide, which is immediately converted by the oxygen present into nitrogen peroxide. The latter then reacts with the aqueous vapor present, forming nitric acid and liberating nitric oxide in accordance with the well-known equation 3NO, +1,0 = 2HNO, + NO. It has been found, however, that the continued passage of sparks through the same quantity of moist air does not result, as might at first sigbt be expected, in the conversion of more and more of the atmospheric gases into oxidized products. For the passage of sparks through the gaseous oxides of nitrogen first formed results in their decomposition again into their elementary constituents. If, for instance, spark discharges are passing at the rate of one per second, the whole of the nitrogen peroxide molecules have not time to react with the water molecules to form nitric acid, before the passage of the next spark, and hence some of them suffer decomposition; indeed, it is probable that a number of the nitric oxide molecules first formed have not even time to combine with oxygen to form the peroxide before the passage of the next discharge, which brings about their dissociation. Hence it is, that, in a closed space, a limit is soon reached beyond which there is no further increase in the amount of nitric acid. For this reason the yield of nitric acid has hitherto been very small. Dr. V. Lepel has made experiments, therefore, with a slowly-moving atmospbere, and under different conditions of pressure, and with various types of spark discharge, with the result that he has already increased the amount of combination to 10 per cent of the total amount of air employed. The air is exposed under increased pressure to a series of parallel spark discharges in the same tube. The change of atmosphere is not made continuously, but intermittently, and the gases are expelled from the discharge tube into a large absorption vessel, in which the products are absorbed in a solation of water, or of a caustic alkali. Detailed accounts are given in the memoir of the efficacy of the various forms of hightepsion discharge, and Dr. V. Lepel is now experimenting with

the discharge from a Töpler influence machine with sixty-six rotating plates. Of particular interest are his remarks concerning the probable effect of the high-voltage discharges of which we have lately heard so much. He considers it not improbable that by their aid a new mode of producing nitric acid from the atmospheric gases on the large scale may be introduced, rendering us altogether independent of the natural nitrates as a source of nitric acid.

- According to the Pioneer Mail of June 8, the residents of Howrah have been finding lately that jackals are animals of anything but an attractive temper. In some cases they have come right up to the bungalows in search of prey. A little girl, aged about five years, was playing in a verandah, when a jackal suddenly rushed on her, and was dragging her away, when she was rescued. She was severely bitten. Three natives, while walking along the Kooroot Road, were attacked by a jackal, which was only driven off after a stubborn fight; and a tale is told of two women, while standing near a tank, being attacked and bitten. So serious has the state of matters become that the public propose to submit a memorial to the district magistrate praying for the adoption of measures for the destruction of these pests.

- C. Creighton, in a letter to Nuture, June 30, on the immunity of the African negro from yellow fever, says:

• This point, interesting to anthropologists, is raised anew by a writer on the history of epidemics (Nature June 16), who asks whether the alleged protection is supported by all recent authorities. Recent authorities are not so well placed for judging of this matter as the earlier ; for the reason that immunity is not alleged except for the African negro of pure blood or unchanged racial characters, and that these conditions of the problem have been much less frequently satisfied in the yellow fever harbors of the western hemisphere since the African slave trade ceased. However, there was a good opportunity in 1866, during the disastrous yellow fever among the French troops of the Mexican expedition when they lay at Vera Cruz. Among them was a regiment of Nubians, who had been enlisted for the expedition by permission of the Khedive: that regiment had not a single case of yellow fever all tbrough the epidemic. The African negro regiment brought over from the French colonies of Martinique and Guadeloupe had two or three cases, with, I think, one death. The rest of the troops, including Frenchmen, Arabs from Algeria, native Mexicans and Creoles, bad no immunity whatever, but, on the other hand, a most disastrous fatality. The medical officers of the French service have recorded the facts principally in the Archives de Médecine Navale, their conclusion as to racial immunity being the same that has passed current among the earlier authorities as a truth of high general value (admitting, of course, of exceptions in special circumstances), and a truth that has never, so far as I know, been formally controverted by anyone, although other points concerning yellow fever have been the subject of as obstinate controversy as those touching small-pox itself. The experiences of the French at Gorée, a town with ten times as many negroes as wbites, exactly confirmed those of Vera Cruz in the same year (Arch. de Méd. nav., ix., 343). The immunity of the African negro from yellow fever has become a paragraph in some anthropological text-books. It is from the anthropologists, and not from medical authorities, that Darwin cites the fact in his “ Descent of Man," adding an original theory of the immunity, which he was unable to establish after much inquiry. His theory, I need hardly say, was not that “negroes in infancy may have passed through some disease too slight to be recognized as yellow fever,” – whatever that may mean “but which seems to confer immunity." The theory, however, is another story, or “another volume," as the writer just cited is pleased to suggest ; and as for the historical fact of immunity, no one denies it, unless it be Dr. Pye Smith in his recent Lumleian lectures (Lancet, April 23, 1892, p. 901), who gives no reasons. It is unfortunate that the anthropologists (Darwin among them) should have introduced one element of dubiety in placing mulattoes on the same footing, in respect of immunity, as negroes of pure descent, and another in mixing up malarial or climatic fevers with yellow fever.”

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