amount." In order to give this increase, about 1.5 cwt. of nitrate of soda would be required to be applied annually to each acre, that is to say, 12,000,000 tons would be needed. As at present situated the world is not in a position to supply this vast amount of nitrogenous product. Since Crookes sounded this note of warning many attempts have been made to oxidise atmospheric nitrogen on a commercial scale, but until within the last fifteen months no process based upon electrical oxidation has been an actual commercial success. It yet remains to see whether the process of Drs. Caro and Frank, which depends upon the formation of calcium cyanamide, will be able to compete in the first place with natural nitrates and ammoniacal products, and, secondly, with the electric process of Birkeland and Eyde, which, as we will shortly show, appears to have solved the problem of the fixation of atmospheric nitrogen. Drs. Caro and Frank found that by passing nitrogen over heated barium carbide barium cyanide was produced thus,

BaC2+N2=Ba(CN)2,.

but that when calcium carbide was employed calcium cyanamide and not calcium cyanide is formed,

CaC,+N, CaCN,+C.

When the cyanamide is heated with water under pressure it is decomposed with formation of ammonia and calcium carbonate,

CaCN,+3H,O=CaCO,+2NH,. This process is stated to take place slowly when the cyanamide is distributed on the soil. Although the manufacturers state that cyanamide is stable and does not deteriorate on keeping, some at least of the users say it is unstable and deteriorates considerably as a fertiliser when kept.

As

An electrical process-that of Bradley and Lovejoy -which was almost a success, was worked for about eighteen months at Niagara. They employed a continuous current with a potential of 10,000 volts. it is very difficult to keep steady discharges at this high voltage, a slowly rotating framework with projecting electrodes was employed. As it rotated, the electrodes, which were of platinum, approached other projecting electrodes; discharges were thus provoked, but immediately interrupted. In an apparatus of only 5 kilowatts as many as 414,000 arcs were produced per minute. The working of such an apparatus on a technical scale was, as might be supposed, of great difficulty, and although considerable quantities of nitric acid were produced per kilowatt year, it did not prove commercially successful.

In May, 1905, a factory was started at Notodden, in Norway, for the manufacture of calcium nitrate from air and limestone by means of the electric arc flames. A photograph of the factory as it is at present is shown in Fig. 1. In the Birkeland-Eyde process, which is worked at Notodden, a high-tension are flame is produced between two pointed copper electrodes. The electrodes are attached to a high-tension alternator, and are placed equatorially between the poles of a powerful electromagnet, so that the terminals of the electrodes are in the middle of the magnetic field. An electric disc flame is thus produced which is shown diagrammatically in Fig. 2, and a photograph of the actual flame in Fig. 3. The photographed flame, which represented about 250 h.p., was produced between water-cooled electrodes made of copper tubing.

The working potential employed is 5000 volts, the current is an alternating one of 50 periods per second, and the distance of the terminals apart is about 8 mm. As already mentioned, the electrodes are copper tubes

cent. of the electric energy employed between the electrodes is removed as heat by the water.

Prof. Birkeland explains the formation of the discflames in the following way :-" At the terminals of the closely adjacent electrodes, a short arc is formed, establishing an easily movable and ductile current conductor in a strong and extensive magnetic field, i.e. from 4000 to 5000 lines of force per sq. cm. in the centre. The arc then moves in a direction perpendicular to the lines of force, at first with an enormous velocity which subsequently diminishes; and the extremities of the arc retire from the terminals of the electrodes. As the length of the arc increases, its electrical resistance also increases, so that the tension is increased until it becomes sufficient to create a new arc at the points of the electrodes. The resistance of this short arc is very small, the tension of the electhat the outer long arc is extinguished. . . . In an trodes therefore sinks suddenly, with the consequence

&.

мийш

FIG. 2.-Diagram of electric arc flame.

alternating current all the arcs with a positive direction of current run one way, while all with a negative direction run the opposite way (see Fig. 2), presupposing the magnetising being effected by direct currents. In this manner a complete luminous circular disc is presented to the eye."

It is interesting to note that the flame, considering its high electrical power, is not particularly luminous, as it is quite possible to look directly at it with the naked eye at a distance of about 1 yard, and it is not easy to snapshot it.

The alternating-current disc flame is enclosed in special furnaces which are lined with firebrick and enclosed with metal casing. The fire-chamber of the furnace is narrow in the direction of the lines of force-from 5 cm. to 15 cm. wide-and made partly of perforated firebrick, the air being conveyed to the flame in an evenly distributed supply through the walls. The magnetic system is composed of two powerful electromagnets, the extremities of which are turned in towards the fire-chamber. The air is driven into the central region on both sides of the flame by gentle pressure from a Roots blower; it must not be blown too rapidly, otherwise the flame is extinguished. Fig. 4 shows three of the furnaces, each furnace taking 500 kilowatts. The volume of air at present treated is 75,000 litres per minute, which after passing through the furnace contains about I per cent. of nitric oxide. The gases leave the furnace at a temperature of 600° to 700° C., and are first passed through a steam boiler, the steam from which is em

calcium nitrite obtained from the fifth tower and to convert unchanged lime into nitrate. The oxides of nitrogen produced by the decomposition of the nitrite are carried back to the system of towers. The solution resulting is run, together with the rest of the stored-up acid, into another series of granite tanks, where it reacts with limestone, thus producing neutral calcium nitrate. This solution is evaporated down until the temperature rises to 145°, answering to a concentration of 75 to 80 per cent. of calcium nitrate. The solution is then run into 200-litre drums, where it solidifies, and it appears on the market in this form. It is, however, found that for fertilising purposes it is better to use the basic nitrate owing to the extremely hygroscopic properties of the neutral salt. The ground-up basic nitrate can, as it is not hygroscopic, be readily scattered with a sowing machine.

Numerous manuring experiments have been made with calcium nitrate at different agricultural institutes. The results show that lime saltpetre is quite as good as Chili saltpetre, and on a sandy soil is even superior.

The yield of anhydrous nitric acid by the Birkeland-Eyde process is between 500 and 600 kilograms per kilowatt year. The cost of calcium nitrate containing 132 per cent. of nitrogen is about 41. per ton,

FIG. 3.-Photograph of electric arc flame, showing water-cooled electrodes.

ployed in the further manufacture of calcium nitrate. After passing from the boiler the temperature is about 200°, and by passage through a cooling arrangement the temperature is reduced to 50°.

The gases now pass into two large oxidising chambers with acid-proof lining, where the oxidation of the nitric oxide formed in the furnaces takes place with production of nitrogen peroxide. It is then conducted into an absorption system consisting of five towers, two being of granite and two of sandstone, filled with broken quartz over which water trickles, nitric acid thus being produced. The fifth tower is filled with broken bricks over which milk of lime trickles and which absorbs the now rarefied nitrous gases with formation of calcium nitrate and nitrite. In the plant at Notodden there are two such series of towers. The liquids from the fourth tower, which consist of 5 per cent. nitric acid, are raised to the top of the third tower by compressed air, those from the third to the second, and from the second to the first. The acid, on leaving the third tower, is of 15 per cent. strength, on leaving the second 25 per cent., and it leaves the fourth tower with a strength of 50 per

cent.

Some of the acid produced is used to decompose the

FIG. 4.-Photograph of three 500-kilowatt furnaces at Notodden.

and the selling price about 81. per ton. New works of 30,000 h.p. are now nearly completed, and it is hoped that the new factory will be very shortly in active operation. To an Englishman it is of interest to notice that all the pioneer work was carried out in this country. In this connection it should be remarked that even if the final stage-the application of the flame electric arc-had been tried in this country, it could not have been a commercial success. To be a commercial success it is absolutely essential that very cheap power should be at the disposal of the manufacturers. At present we have not this cheap power, and it is very improbable that we shall have it in the near future; unless, indeed, some engineer can show us how to harness the tides. But if we cannot manufacture nitric acid from the atmosphere there is a problem, probably a very difficult problem, the elucidation of which would be of almost untold value, and that is the fixation or utilisation of the nitrogen in sewage, which at present is almost entirely thrown with happy abandonment into the sea. As a consequence, the mouths of rivers are polluted. fish are destroyed, and, what is perhaps more serious. disease is often disseminated.

F. MOLLWO PERKIN

was deduced that isolated nerve, by reason of its showing no fatigue, but giving perfectly regular responses, is a favourable symbol of living matter on which to study the effect of drugs and reagents. From these experiments was proved the fact that chloroform is eight times more powerful than ether, and that 2 per

negative then positive,

cent. vapour of chloroform is the safe dose. Dr. Waller attributed deaths from overdose of chloroform to inattention to the great scientific principle of measurement.

Records were shown of the electrical effects produced by a series of illuminations of the eyeball, and of similar effects produced by pressure on the eyeball and by electrical excitation; Dr. Waller at first thought these latter effects were the same as those produced by light on the retina, and called them "blaze currents," but afterwards found they were characteristic of all living tissues. The petal of a flower and living seeds give blaze currents.

Dr. Waller described his records of the electrical effects of light on a green leaf; sunlight and the arc light were used; it seemed natural that the vegetable retina should be sensitive to light; the response is a double one, first dissimilation then assimilation;

ployed in the experiments, 12 and showed the methods by which the photographic records were obtained.

The physiologist is engaged in the task of learning how plants and animals absorb, transform, distribute, and dispense the energy stored in food and manifested in each act of life-in a word, of studying the signs of life; and in the electrical change which accompanies all chemical change we have the most delicate means of addressing two questions to living matter: Are you alive? How much are you alive?

Tissues survive the death of the animal or plant. Six objects were chosen as representative examples of living matter-muscle, nerve, retina of the eyeball, a green leaf, a flower petal, and a seed. The characteristic of life is perpetual change, metabolism-building up and breaking down - anabolism,

8981

and katabolism. From the records shown of the electrical responses to excitation of muscle and nerve, it

voll 0.034

ми

024

07014

0.004

1 Abstract of lecture delivered by Dr.Augustus D. Waller, F.R.S., to the members of the British Association at York.

Humidity:

Date of ascent

The

METEOROLOGICAL KITES IN INDIA.

TH HE India Meteorological Department has recently given in a number of its Meteorological Memoirs (vol. xx., part i.) "an account of the preparations made for determining the conditions of the upper air in India by means of kites." The Government of India, acting on a strong recommendation by the Royal Society, about three years ago sanctioned the inclusion of the exploration of the middle and higher atmosphere by means of kites and balloons as a part of the scheme of operations of the Meteorological Department. Two officers were deputed to Germany to study the methods employed by the Aeronautische Observatorium des Königlich Preussischen Meteorologischen Instituts. The first part of the memoir gives a description of the instruments employed, and the results obtained from the first preliminary ascents. The place selected for these was in Lower Sind, about six miles W.N.W. of Karachi, a mile from the sea and ten miles from the Hala Range on the west, forming the boundary between Lower Sind and Baluchistan.

The ascents were made in the last week of August and first fortnight of September, 1905, shortly before the withdrawal of the south-west monsoon current from Upper India.

In order to appreciate the results, it is necessary to bear in mind that during the wet monsoon in India an area of minimum pressure stretches from Upper India to the Soudan, in which pressure is absolutely lowest in Sind. The intensity and position of this varies considerably during the season. The observations were hence made in the south-west quadrant of this area of minimum pressure, where the lower cyclonic air movement is probably light and irregular, due to the obstructive action of hill ranges of moderate elevation.

The observations showed that a humid current (approaching saturation) obtained on the average up to an elevation of about 2500 feet (from about W.S.W.), and that above this was a very dry current from west with slight northing, the intermediate region of transition from the humid to the dry being probably less than 1000 feet in thickness. The accompanying table gives selected data from the two most satisfactory ascents.

The very dry current represents indraught from the Baluchistan plateau to the Sind low-pressure area, which, however, as a result of the presence of hills, entered it at a considerable elevation, exceeding on the average 2500 feet. The most remarkable feature is the large increase of temperature in passing from the lower humid current into the upper dry current, of + C. to 7° C. in amount, and of the comparatively

slow rate of decrease for some distance above that plane of transition. Almost equally remarkable is the sudden and comparatively abrupt change of the relative humidity from saturation to values of 5 and 6 only. Mr. Blanford many years ago established that in drought years in North-Western India

this dry current from Baluchistan descends to the level of the plains in Sind and extends southwards and eastwards to very considerable distances, and is an important factor in determining the intensity of the drought in North-Western India, and perhaps of conditioning it. Another point of interest is the com paratively rapid variation, even in short periods of the lower level of this dry current. Mr. Field. who carried out the observations, says that "a nearly saturated stratum of air from the sea extended from the ground surface (10 metres above the sea) upwards to a level which rose from 500 metres on August 27. through 800 metres on August 28, to 1130 metres on August 31. From that day onwards until September its limiting height was not reached by the kite, but probably exceeded 1000 metres. Its upper limit fell again to 600 metres on September 12."

The observations give valuable and interesting information of what may perhaps be termed an outlying portion of the south-west monsoon current. They suggest that the extension of the work will give most important information respecting the south-west monsoon circulation, and perhaps on the causes of the variation of the intensity and extension of the southwest monsoon rainfall, one of the great problems which for some time past has engaged the earnest attention of the Meteorological Department at the instance of the Government of India.

NOTES.

WE deeply regret to announce the death, at the age of seventy-four years, of Mr. C. Baron Clarke, F.R.S., which took place at Kew on Saturday last, and, at the comparatively early age of fifty-two years, of Prof. H. Marshall Ward, F.R.S., which occurred at Babbacombe, Torquay Sunday last. Prof. Ward, who had been ill for some months, had filled the chair of botany at the University Cambridge since 1895.

ON August 20 there passed away at his beautiful country seat, Coles Park, near Buntingford, Herts, in his eightis year, one who is well known to mineralogists 20 je n author with the late Mr. W. G. Lettsom of the "Mani. } of the Mineralogy of Great Britain and Ireland," a whose name will ever be linked with perhaps the finest private collection of minerals which was ever brough together in this country. Mr. Robert Philips Greg as ? young man took great interest in the fine collection wha his father, a noted economist and antiquary, had purchasevi from the executors of its previous owner, Mr. Thom Allan, F.R.S., and spent considerable sums of money in acquiring new specimens and bringing the collection up " After the publication of his "Manual " in 18;8

date.

appeared to take little active interest in minerals, and two years later, in 1860, the Allan-Greg collection was purchased by the trustees of the British Museum. For many years afterwards he still devoted himself to the study of meteorites, from both the astronomical and mineralogical points of view, until paralysis of the legs rendered it difficult for him to move about. The "Manual" referred to was published nearly half a century ago, and probably few mineralogists will realise that one of the authors has died so recently.

THE death of M. Alexandre Herzen, professor of physiology in the University of Lausanne, and author of many books dealing with physiology and allied subjects, is announced in the Temps.

Science announces the death of Prof. S. L. Penfield, head of the department of mineralogy in the Sheffield School of Yale University; also of Mr. G. W. Lehmann, chemist of the United States Government since 1878, and chief chemist of the Baltimore Board of Health since 1896.

THE death is announced from Tangier of M. Georges Salmon, leader of the French scientific mission to Morocco. A MOVEMENT has been set on foot in Germany to raise a memorial fund for the benefit of the widow and children of the late Dr. Schaudinn, and an English committee consisting of Prof. Clifford Allbutt, F.R.S., Sir Michael Foster, F.R.S., Mr. Jonathan Hutchinson, F.R.S., Prof. Ray Lankester, F.R.S., Sir Patrick Manson, F.R.S., Prof. Osler, F.R.S., Mr. John Tweedy, and Prof. Sims Woodhead has been formed to cooperate with the German promoters of the scheme. Subscriptions may be paid to Mr. Adam Sedgwick, F.R.S., treasurer of the fund, New Museums, Cambridge, or direct to the Schaudinn Memorial Fund at Messrs. Barclay and Co.'s Bank, Cambridge.

A CONFERENCE of the International Geodetic Association will be held in Budapest on September 20 next, when, according to the Temps, the principal topics to be considered will be the accurate surveying of mountain chains subject to earthquake, with a view to ascertaining whether these chains are stable or whether they rise and sink, and the taking of measures of gravity so as to throw light upon the distribution of masses in the interior of the earth and upon the rigidity of the earth's crust. The drawing up of preliminary reports on these two questions has, says our contemporary, been entrusted to M. Lallemand, director of the general survey in France, and Sir George Darwin, K.C.B., F.R.S.

THE King of the Belgians has shown his practical interest in the study of sleeping sickness by offering a prize of Soool. for the discovery of a remedy for the malady, and by placing a credit of 12,000l. in the Congo Estimates for the purpose of prophylactic research; he also recently rereived representatives of the Liverpool School of Tropical Medicine, and having heard their views as to the necessity of preventing the further spread of the disease, asked the school to submit to him a scheme of preventive measures. The King bestowed the Order of Leopold upon Prof. Ronald Ross, C.B., F.R.S., Prof. Boyce, F.R.S., and Dr. J. L. Todd.

FURTHER slight shocks of earthquake are reported from Valparaiso and Santiago; slight shocks have also been felt at Carcoar, twenty-five miles from Bathurst, New South Wales.

Ax earthquake shock is stated to have been felt at 5.55 a.m. on Monday last at Matlock and other parts of

Derbyshire. The shock, which was very slight, was accompanied by a sound like distant thunder, and lasted three or four seconds.

THE Wellman Polar Expedition has been abandoned for the present, its leader having decided not to attempt the voyage northward this year on account of defects in the mechanical equipment of his airship. Mr. Wellman is to return to Europe in the middle of next month, and will leave a small party of men behind to guard the headquarters of the expedition.

A ROYAL Commission has been appointed to inquire into the lighthouse administration of the United Kingdom. The terms of reference are:-"To inquire into the existing system of management of the lights, buoys, and beacons on the coast of the United Kingdom by the three general lighthouse authorities, and as to the constitution and working of these authorities, and to report what changes, if any, are desirable in the present arrangements."

A HEALTH, Electrical, and Gas Exhibition is to be held at Portsmouth from November 5-27 next.

THE Latin-American Medical Congress will be held at Monte Video in January next.

THE fourth Portuguese Congress for the Prevention of Tuberculosis will be held at Oporto from April 4-9 of next year.

ACCORDING to the Electrical Review, an international competition has been organised by the Association des Industriels de France for the invention of a primary cell and a storage cell satisfying certain conditions. Both cells are to develop the maximum power or contain the maximum energy possible per unit of weight and bulk, and they must be free from risk of every description to the users, easy of transport, installation, and maintenance. The samples submitted must not weigh more than 20 kg. Complete descriptions of the cells must be forwarded by the competitors before the end of the present year to the president of the association, 3 rue de Lutèce, Paris, with drawings, and the actual cells must reach the examiners by April 1, 1907. The prize money, amounting to 8000 francs, may be awarded as a lump sum or divided at the discretion of the association.

THE Legislature of the Berne Canton has sanctioned the project for the construction of a new trunk line-the Lötschberg-with electricity as the motive power, which will pass through the Bernese Alps and connect at Brig with the Simplon. The new line will be 56 kilometres in length, of which 133 kilometres will be tunnel. It will serve as the most direct means of communication between northern Italy and the district lying to the north and northwest of Switzerland, shorten the approach to the Simplon, and compete with the Gothard tunnel railroad. The work, which is to be begun at once, is estimated to require five and a half years to complete.

THE Australian correspondent of the Lancet states that the Federal Government has issued a proclamation prohibiting the importation of the microbe of hæmorrhagic septicæmia, by which it was proposed to destroy the rabbit pest, except upon the condition that the packages containing the microbes be handed unopened to the State bacteriologist of New South Wales, and retained by him unused until the Minister gives permission to use them. Under the Noxious Microbes Act of 1900 of New South Wales it will also be necessary for the State Government to pass a regulation sanctioning experiments before anything can be