ON T H E UTILISATION OF THE ATMOSPHERIC NITROGEN IN THE PRODUCTION OF CALCIUM CYANAMIDE, AND ITS USE IN AGRICULTURE AND CHEMISTRY. BY DR. ALBERT R. FRANK. ( A Paper ?,cad hefove the Farnti1i.y Society 01% Tuesday, ?fine 9, 1908, Dr. F. MOLLWO PEKKIN Ln the Chair.) When Liebig, about the middle of last century, laid down the scientific basis of the natural laws of agriculture and the cultivation of plants, he showed that the essential condition for ensuring the soil against loss of plant- food, and thereby enabling it to maintain its fertility, was the supply of such mirzeral foods as the plants require for their growth. These mineral foods are continually being withdrawn from the soil, where they are by no means over- abundant in available form, by the crops. Among such foods Liebig placed phosphates and salts of potassium in the front rank, and thus founded his theory of mineral manure.As regards bodies like oxygen, hydrogen, carbon, and nitrogen, which are used for building up the intrinsic organic plant substances, Liebig maintained, in opposition to the supporters of the vegetable theory, which was believed in up till then, that the requirements of vegetation were continually and adequately supplied by the atmosphere, and that the effect of the nitrogen contained in certain bodies widely known in practice as efficacious manures, such as bone ash and guano, was of less importance than that of the other inorganic plant foods. Technical chemists adopted Liebig’s suggestion with enthusiasm and success. After the discovery of the rich mineral phosphate deposits, the conversion of these into the higher phos- phates by treatment with sulphuric acid was utilised with much success.The author’s father, Professor A. Frank, of Charlottenburg, succeeded, after the Stassfurt deposits were discovered, in placing at the disposal of agriculturists, the world over, an inexhaustible supply of the much needed potassium salts. As a result of the successes achieved in agriculture by Liebig’s minera2 theory, observant investigators, and amongst the first of these Liebig himself, could not in the long run ignore the fact that, by the addition of bodies con- taining nitrogen to the mineral manures, an essential requirement of plant life was met, and, at the same time, an improvement in the financial con- dition of the manure trade must ensue.In consequence an immediate demand for manures containing nitrogen, most of them of organic origin- e.g., bones, blood, offal, and fish guano-arose. These, however, only partially supplied requirements, while at the same time the Peruvian deposits of animal guanos were being very rapidly depleted by an ever increasing demand, I t became necessary, therefore, to turn to those inorganic compounds of nitrogen which had definitely been proved by scientific research to be suitable for plant food. Of these the two most important were the salts of ammonia, especially ammonium sulphate, the manufacture of which on a large scale from the gas liquors was first carried out in England in the early sixties, and the nitrates, of which an extensive deposit, in the form of sodium nitrate, was discovered on the rainless plateaus of Peru and Chili as early as 1830.Their application to agriculture, however, dates from 1860. Since ammonium salts 99IOO T H E UTILISATION OF ATMOSPHERIC NITROGEN have up till now only been profitably obtained as a by-product in the manu- facture of coal, gas, and coke, their production, in spite of the great increase from 10,000 tons in 1860 to about 600,000 tons last year (of which England uses up some 316,000 tons), is limited and dependent on other factors than agricultural demand. OUTPUT OF AMMONIUM SULPHATE IN ENGLAND. Year. I 898 1900 1901 1902 I903 I904 '905 1906 '907 I899 Total Production. Tons. 196,500 208,000 210,000 228,500 229,000 234,000 245,000 268,500 289,000 3 16,000 Average Price Per Ton.& s. d. 9 2 78 11 5 9Q I 0 I 1 4 11 16 3 12 9 3 12 3 8 12 I 0 9 I2 0 9 11 I5 3 I1 2 0 Total Home Consumption. Tons. 65,000 58,500 65,000 68,297 68,700 70,200 71,200 75,400 78,000 87,500 Used in Agriculture. This may be anything between 90 to 75 per cent. of the total home consumption, the balance being absorbed in arts and manufacture. OUTPUT O F AMMONIUM SULPHATE I N GERMANY. Year. I899 I 900 1901 I 902 I903 I904 I905 I 906 Total. Tons. 84,000 98,000 100,000 106,500 133,000 140,000 146,000 I 82,000 203,000 235,000 From Coke. Tons. 70,000 84,000 84,500 88,500 I 13,000 I 17,000 120,000 I 52,000 168,000 197,000 __ From Gas Works. Tons. 14,000 14,000 15,500 I 8,000 20,000 23,000 26,000 30,000 35,000 38,000 I t was these circumstances which placed sodium nitrate in the front rank of nitrogenous manures, and which caused the world's demand for these substances to rise from 935 tons in 1830 to about 1,740,000 in 1907 (see Fig.I). Of this amount Europe absorbs 1,400,000 tons and the U.S.A. about 340,000 tons. 20-25 per cent. of this being employed in the manufacture of chemicals and explosives, while the rest is used for agricultural purposes. Germany, which on account of the uncertain climate of its northern provinces, and because of its extensive beet sugar industries specially needs manures, is the largest consumer, importing over 500,000 tons yearly, about 400,000 of which are utilised in agriculturc. The guano deposits which at first were considered inexhaustible have now practically come to an end, and the same remark applies to the strictly limited nitrate deposits in the rainless region of Western South America.Agriculturists and political economists naturally regard with considerable anxiety the approaching disappearance of the deposits, while the demand for nitrates is steadily increasing year by year. Whether the date of exhaustion will be twenty or forty years hence is, on account of the vastIN T H E PRODUCTION OF CALCIUM CYANAMIDE IOI importance of the question, of little consequence, seeing that even during the last few years the price of sodium nitrate has risen 35 to 40 per cent. (in Germany), an increase due less to speculators than to higher working expenses and growing difficulty of production. It is also manifest that the chemical industries can afford to pay for the nitrate-which they consume in the pro- duction of nitrogenous compounds, nitric acid, and explosives-higher prices than the agriculturist is able to give.The price of sodium nitrate reveals, in addition, the state of the market for other nitrogenous manures. Ammonia and ammonium salts have likewise shown a marked advance, and agricul- turists who have urgent need of these manures, not only for producing their present average crops, but also for securing the increased output made neces- sary by the growth of population, an urgent necessity pointed out some years ago by Sir William Crookes, were threatened with a serious nitrogen famine. t8io dd30 4950 /d?o d@O A9P FIG. I.-SALTPETRE PRODUCTION IN CHILI. It is well known to all that the atmosphere surrounding our earth contains a diffused and practically inexhaustible supply of nitrogen, totalling about 4,041,200,000,000,000 tons.This works out at 31,000 tons of nitrogen over each acre of the surface of the globe, or the still air over every nine acres contains about 280,000 tons-ie., the same amount which is contained in the 1,740,000 tons of Chile saltpetre exported from that country in 1907. We know, further, that uncultivated plants, partly through certain organs which exist in them, as well as in leguminous plants, and partly by the aid of bacteria inhabiting the soil, are able to absorb the nitrogen they require from the air diffused through the soil. Furthermore in 1775 Priestley showed that atmospheric nitrogen under the influence of the electric spark combined with atmospheric oxygen to form nitric acid, the latter being conveyed by moisture to the soil and then to the plants.But all this accumulated experi- mental knowledge, important though its results undoubtedly were, did not afford any clue to the possibility of producing nitrogen compounds in con- siderable masses, nor was it freely at the disposal of agriculturist or chemist. The method devised by Fownes and Young last century, and experimentally applied by Bunsen and Playfair, showed that by passing atmospheric nitrogen over carbon and the alkalies or alkaline earths, the carbon compound102 T H E UTILISATION OF ATMOSPHERIC NITROGEN cyanogen could be formed from which by further treatment ammonia could be obtained.This method, in spite of its extensive application and the many improvements which Marguerite and Sourdeval and later Ludwig Mond introduced in its technical details, produced no practical result, on account of the difficulty of attaining the requisite temperature. It was further com- plicated by the fact that the construction and maintenance of the apparatus, owing to the materials used in the furnaces, gave rise to what were then insuperable difficulties. The first successful advance was made through the discovery and application of the dynamo, which rendered it possible for electricity to be supplied in considerable quantities. By this means a hitherto unattainable temperature could be produced in quite a restricted space. Up to this time, now some few years ago, the necessary energy had to be obtained, except in so far as it was produced by reaction from the molecular energy of the elements, by means of the chemical process of combustion.” With the application of the dynamo and the invention of the electric furnace by Siemens, this process was greatly modified, as by means of electric energy thus applied heat could be produced by means of the electric arc or of an electrical resistance, and could be brought to bear directly on to the chemically reacting mix t ure.With these improved means at their disposal, investigators endeavoured once more to find a solution, as already stated, of the all-important question of the fixation of nitrogen. Subsequent to 1894, when Thomas L. Willson and Moissan carried on the manufacture of carbide on a large scale in the electric furnace, the author’s father, Prof.A. Frank, in a Paper’ published in February, 1895, opposed Moissan’s views as regards the possible use of this carbide combined with atmospheric nitrogen, for the preparation of cyanides and amides. Tests carried out in conjunction with Dr. N. Car0 on this point established the truth of his hypotheses and further led to the invention of a method for the preparation of cyanides, cyanamides, ammonia, and other nitrogen com- pounds. It is on the technical and industrial manufacture of these and their value that the author has this evening to speak to you. The other way of fixing nitrogen, on which much successful work has been accomplished, by oxidising it and turning it into nitric and nitrous acid by means of the electric spark, was soon established on practical lines, firstly with unsatisfactory technical results at Niagara Falls by Bradely & Lovejoy, and then by the magnificent discovery of Birkeland & Eyde, as well as by the improvements which are now being perfected due to Schonherr and the Badische Anilin and Soda Fabrik.Prof. Birkeland made some highly interesting remarks on the oxidation of atmospheric nitrogen in this room in July, 1906, which you will all remember. In amplification of these the author may add that the production of calcium nitrate by the Birkeland-Eyde process seems to be developing exceedingly well in Norway, and that the factory mentioned by Prof. Birkeland is actually established at Notodden and is producing this substance.It should, however, be noticed that this industry has not made much progress in any other land save Norway, but it should not be forgotten that it is only in this Northern clime that electrical energy can be as cheaply obtained on account of its unrivalled resources of water power. It would therefore seem probable that Norwegian saltpetre is destined to remain the only direct competitor of the Chilian variety. As will be seen later on in my Paper, the two methods of nitrogen fixation I Vcrharzdlungen des Vereiizs ZILY Bc/ordeung des Gewerbflcisses, 1895, No. 2, February : (‘ ffber Gewinnung von Acetylen und dessen Verwendung zur Herstellung von Alkohol,” &c. By Dr. Adolph Frank Charlottenburg.IN THE PRODUCTION OF CALCIUM CYANAMIDE 103 differ greatly as regards their chemistry.Physically they are similar ; for, properly speaking, they are not electrical, but should be considered purely thermal processes. They do, however, differ in that the fixation of nitrogen by carbide is an exothermic process, in which heat is given out, while the combination of oxygen and nitrogen is endothermic--i.e., it absorbs a large amount of heat, and for the fixation of an equal quantity of nitrogen requires at least three times the energy that the former process calls for. The researches instituted, as mentioned above, by Frank & Car0 in 1895 were first carried out on calcium carbide mixed with sodium carbonate. But as the yield of cyanide obtained in this way proved unsatisfactory, they soon substituted carbide of barium therefor, a substance which at that time could be more easily obtained, and this they found absorbed nitrogen isolated from the air with great avidity at a temperature of between 700° and 800° C.Frank and Car0 were then contemplating the transformation of barium cyanide by treatment with carbonate of sodium or potassium into cyanide of potassium, which at that time commanded a very high price, with a considerably increasing demand. The first experimental plant was con- structed with the object of perfecting as far as possible the process for obtaining cyanide of potassium and yellow prussiate. They soon found that the nitrogen absorbed by barium carbide was not merely in the form of cyanide (Ba (CN),), but that it was also present in the form of a more complex compound. The latter was found, on examination, to be cyanamide of barium BaCN,, from which they inferred that the reaction had taken place according to the following equation- BaC, + 2N = BaCN, + C.Thus it appeared that in the reaction of carbide on nitrogen half of the carbon contained in the carbide had been set free. The proportion of cyanide and cyanamide of barium in the reacting mass was on an average as two to three, the product containing 30 per cent. of barium cyanide and 45 per cent. of barium cyanamide, the remainder consisting of barium oxide and car bo n . The transformation of the barium cyanamide into barium cyanide could be easily brought about by melting the mass containing both cyanamide and cyanide, with a flux such as potash or soda according to the following equa- tion- Ba (CN) , + BaCN, + C + 2K, CO, = 4KCN 3- 2BaC0,.The great progress which had meanwhile been made in manufacturing carbide of calcium on an industrial scale gave rise to a renewed attempt to try again the method of treating carbide of calcium with nitrogen, which had been previously abandoned owing to the difficulties which it offered at first starting. It was then discovered that the small yield of cyanide obtained in using carbide of calcium without an additional flux could be further reduced, and that no cyanide need be formed at all, but that the reaction wbuld proceed in accordance with the following equation- CaC, + 2N = CaCN, + C, and result in the formation of cyanamide of calcium alone, whilst, as has been seen, in using carbide of barium the corresponding cyanide was also formed.About this time the patentees, Messrs. Frank and Caro, together with the well-known electrical firm Siemens and Halske, and the Deutsche104 T H E UTILISATION OF ATMOSPHERIC NITROGEN Bank of Berlin, founded the Cyanid Gesellschaft of Berlin, for the further development of the process. The primary object of the new Company in taking up these inventions was to turn cyanamide of calcium into cyanide of potassium, for which there was an extensive and increasing demand for the purposes of gold extraction in South Africa and the United States. It is common knowledge that this object was successfully accomplished, The low atomic weight of calcium carbide compared with barium carbide, owing to which 64 parts in weight of calcium carbide sufficed to bind about 28 parts of nitrogen, seemed to point to the conclusion that by using calcium carbide it might prove feasible to produce those nitrogenous compounds also in which the nitrogen would only command a low price, such as fertilisers, &c.Further research in this direction was starting with calcium cyanamide as the raw material for producing ammonia, especially when it turned out that the total nitrogen contents of the calcium cyanamide could by treatment with hot water be turned into ammonia without any difficulty or loss. The process is effected according to the following equation- CaCN, + 3H,O = CaCO, + 2(NH,). In spite of the fact that this reaction requires an excess of water and a high temperature, and that acknowledged authorities on agricultural subjects passed unfavourable opinions in view of the presence of the poisonous cyanide group in the product, in consequence of a proposal made by me, an attempt was made to utilise crude calcium cyanamide directly as a fertiliser, burying it in the ground like any other manure.These experiments were first carried out in pots only. The results were satisfactory enough to indicate that the doubts entertained as to the applicability of the product as a fertiliser were groundless. Thereupon field experiments were arranged on an adequate scale at a large number of agricultural experimental stations, in most countries posscssing agricultural interests, and in connection with almost every class of agricultural produce, and these have been continued for the last six years without intermission.’ As has been the case with many other artificial ~nanures, a great outcry was, and still is, made warning farmers against the use of calcium cyanamide, popularly known as nitrolim, or at least advising that it should be employed with the utmost caution.*This outcry originated in the fact that not only farmers but even agriculturists are saturated with intense conservatism, and that initial failures did here and there occur when first using calcium cyana- mide.It is, however, certain that manufacturers must in the first instance determine the most suitable form for every new manure, as a string of well- known instances in the case of other manures abundantly proves. Fifty years ago, when the author’s father proposed the use of the potassium salts in the Stassfurt deposits, the chlorine compounds of potassium were not only con- sidered as of doubtful value, but even as harmful, while to-day three million tons per annum are used in agriculture all the world over.In the same way there was a time. when the use of Chili saltpetre was directly forbidden by the contracts of beet sugar manufacturers, while to-day it is considered absolutely infallible by all agriculturists, and in certain processes quite indispensable, The storm raised against calcium cyanamide has been lulled in the same way, and recently Professor Wagner of Darmstadt, one of the greatest authorities on agricultural chemistry, summed up his exhaustive researches I Experiments in the United Kingdom with the new manure have been made at Rothampsted, the Cambridge ‘University Farm, the West of Scotland Agricultural College, Harper Adams Agricultural College, the Highland Agricultural Society, the Dauntsey Agricultural School, and many other agricultural stations,IN THE PRODUCTION OF CALCIUM CYANAMIDE rog on the nitrogenous manuring of plants with Chili saltpetre, salts of ammonia, and calcium cyanamide as follows : “ The prospects for an advantageous use of calcium cyanamide are very bright, especially as regards its use for winter fruits.Calcium cyanamide can only be harmful in agricultural practice when it is submitted to abnormal decomposition through uizfavourable circum- stances. Such conditions are especially present in the cultivation of poor lands, such as high moorland and sandy soils which are inclined to be acid, and though rich in vegetable properties are poor in lime.I t is, however, well known that this soil behaves in an abiiormal maniaer to other nitrogenous maiaures. In order to prevent the unsuitable conditions of acid soil previous liming is necessary.” It was, besides, only natural that the manufacturers who were not in a position to turn out manure in bulk complying with all these demands should not have been very favourable. To-day, however, things are very different. A product is actually manufactured containing 20 per cent. and upwards of nitrogen-that is, considerably more than did the earlier products-which recently has further been submitted to a successful dust-removing process, is packed in air-tight sacks, and its efficacy appreciably increased thereby ; there can be no longer any doubt that calcium cyanamide is in a position to compete industrially with any other nitrogenous manure.In this connection the question of price is of the highest importance. Now, as the cyanamide industry has been perfected in the course of the last few years, it must be considered to form, on the basis of the percentage of available nitrogen, the cheapest, and therefore for agriculturists the most economical, manure of the present time. When the first consignments of calcium cyanamide were placed on the market the question of packing and storing was not fully understood. The result was that the product, containing a large amount of free lime, under the influence of atmospheric moisture was naturally converted into calcium hydrate. This caused such a large increase in the volume of the material that the jute sacks containing it burst.The theoretical proportion of nitrogen showed a decrease which was not ascribed, as it should have been, to the increase in total weight but was thought to be due to the fact that nitrolim lost nitrogen in some form or other when stored. Scientific research has shown conclusively, however, that calcium cyanamide may be kept stable for years without losing its nitrogen. The technical authorities have also taken notice of this fault, as mentioned above, and calcium cyanamide is now supplied by the manufacturers practically free from the influence of atmospheric moisture and packed in double paper and jute sacks.It has a further merit, which is of great importance in agricultural operations where elaborate appliances are wanting : calcium cyanamide can be mixed with most widely different manures without loss. For instance, mixed manures of cyanamide and potassium salts, basic slag, &c., may be mentioned which have been found eminently successful in practice. Some difficulty is met in mixing cyanamide with super-phosphate, as the free phosphoric acid combines with the free lime of the cyanamide, and is changed from the water soluble to the citric soluble form. To a certain extent this is not preventable, but the interesting and exhaustive work of Professor Hall, the well-known agricultural chemist and director of the Rothamstead agricultural farm, on this subject has proved that by observing certain conditions the mixing of super-phosphate with cyanamide can be easily accomplished, and is both successful and economical.What makes cyanamide especially valuable as a manure is its after-effects. I t is generally decomposed by the chemical and bacteriological constituents of the soil into ammonia, which becomes fixed by the vegetable mould, and106 T H E UTILISATION OF ATMOSPHERIC NITROGEN is not, as is Chili saltpetre, liable to be washed into the drains and so practically lost. For this reason cyanamide which has not been used during the jirst harvest is always available for the second. Researches on this subject show that the after-effects of cyanamide can be very considerable according to circumstances, a property possessed by no other nitrogenous manure.As regards the economy effected by cyanamide manuring the author will shortly describe the great number of tests which have been carried out for more than six years at agricultural research stations and by users in all parts of the world, and render the operation of cyanamide apparent by the help of photographs (see Appendix No. I.). As regards the part which cyanamide or iiitrolini plays in the soil various theories have been propounded. I t appears that when brought in contact with the ground calcium cyanamide is first decomposed through the action of the moisture and of the carbonic acid in the soil into free cyanamide and carbonate of lime according to the formula- CaCN, - H,O - CO, H,CN, - CaCO,.The free cyanamide will then, by absorbing water, probably be further decomposed into urea- The final product of this decomposition has been found to be ammonia, but later nitrate is produced through the nitrification of the ammonia. Special experiments have demonstrated that the process of transformation of calcium cyanamide or nitrolim is assisted by a host of microbes which are to be found in almost all cultivated soil. On this point very important and interesting investigation has been carried out quite recently by Dr. Lohnis and Saba- schnikoff I of Leipzig, and Dr. R. Perotti of Rome.z I t is, however, not only to the production of fertilisers that the scope of the new calcium cyanamide industry has been limited, for it has been also successfully extended to the production from nitrolim of a number of chemical substances to a great extent by utilising derivative forms of reaction long known to science.I am able to show you here some small samples of several of these derived products, all obtained from cyanamide of calcium. Although calcium cyanamide does not display the typical character of the cyanamides, it can, by melting with fluxes, be turned into calcium cyanide, which product can then be treated by well-known methods to yellow prussiate or cyanide of potassium or sodium. The molten mass obtained by melting nitrolim with a flux contains approximately an amount of cyanide correspond- ing to 25 per cent. KCN., the cost of the said molten mixture, to which we have given the name of “ surrogate,” being much less than that of an equiva- lent amount of pure cyanide of potassium, and the material having been shown by the investigations of English experts to be of equal efficiency with pure cyanide of potassium for the extraction of gold and silver.It appears particularly suited to the requirements of the countries where gold and silver are mined, as it can be produced without difficultyat the mine itself where it is to be used. The production of ammonia and ammoniacal salts from nitrolim, to which I have made reference previously, has also been further worked out and I Urttersuchungen iibev Kalkstickstofl und Stickstofkalk, von Dr. Alexis Sabaschnikoff. Dottore Renato Perotti, Su i bncteri delta diciandiainidc. Roma Typo- graphia Enriev Voghera, 1908.Berlin : 1908, Verlag von Paul Pavey.I N THE PRODUCTION OF CALCIUM CYANAMIDE 107 perfected on an industrial scale. You will readily understand that the ammonia obtained by heating CaCN, with water is very pure and free of empyrheuma. It is therefore particularly suitable for the production of pure ammoniacal salts as well as liquid ammonia (see Fig. 2). Further, the author would point out that a number of complex organic nitrogenous compounds have been derived from calcium cyanamide, and are already being produced on a manufacturing scale. Out of the great number of these I will only mention dicyandiamide (CNNH.),, for which there is an increasing demand in Germany for the manufacture of organic dyes, besides which there are urea CONH, and sulphourea CSNH,NH,.‘l’he author would also mention that one of the German companies is producing from nitrolim the salts of guanidine, such as carbonate and nitrate of guanidine, nitro-guanidine, and other salts, all of which should now gradually come into use on an increasing scale in the industries of organic chemistry, as the cost of production will be considerably lower when starting from calcium cyanamide than by the methods of manufacture hitherto employed. Recently attention has been paid to the use of nitrate From Steam- chest - - 1; Ammonia irz= F I G . 2.-DIAGRAM OF A PLANT FOR AMMONIA PRODUCTION FROM LIME NITROGEN. of guanidine, nitro-guanidine, and dicyandiamide as a ‘‘ deterrent ” for reducing the temperature of combustion with explosives and gunpowder. In consequence of the high contents of inert nitrogen in dicyandiamide (66.6 per cent.) it evolves a strong pressure when burnt in a gun, and in contradis- tinction to the other constituents of the explosive which contain more carbon and hydrogen, its decomposition produces but little heat.This peculiarity is of great importance in powder used with ordnance, such as cordite and filite, which, because of the high temperature of combustion, rapidly destroy the rifling of the barrels. With many powder mixtures the cooling action of dicyandiarnide is shown by the disappearance of the flash at the muzzle, so that on discharge both powder smoke and powder flash are done away with. The composition of the crude cyanamide of calcium made it appear likely that it would lend itself quite as well as yellow prussiate and potassium cyanide for use in case-hardening and tempering of iron and steel.Tests carried out to this end have confirmed this impression. It has been shown that by adding certain fluxes to the crude cyanamide of calcium a very high hardening effect can be produced. This new hardening mixture, under the name “ferrodur,” has been introduced on the market in Germany, England, and other countries, and its property of producing an extraordinary depth of the hardened surface without the material being at all deteriorated has already secured it a great number of friends.108 THE UTILISATION OF ATMOSPHERIC NITROGEN If I may ask your indulgence for a few more minutes, I would like to give you a short description of the method by which the nitrolim is being pro- duced in some of the factories, and to say also a few words on its position in the markets of the world.The carbide coming from the electric furnaces is ground, charged into retorts made of fire-proof material which are mounted in a furnace similar to gas-house furnaces (see Fig. 3). The nitrogen is then passed over the carbide at a temperature of from 800’ to 1,000~ C. The carbide used is of the same quality and percentage as that employed for lighting purposes, and the nitrogen consumed is obtained by fractional dis- tillation of liquefied air by the Linde system, or the so-called copper” process in which air has passed through heated copper particles. The copper takes up the oxygen and the free nitrogen passes to the furnaces.The resulting copper oxide is reduced in the same apparatus by treatment with reducing gases or vapours, and the copper which is recovered is then ready for a new cycle. In the Linde process the oxygen remaining after separation of the nitrogen may be utilised for any purposes. As soon as the carbide in the retorts is saturated with nitrogen, a fact which will be made apparent by the controlling gas-meter corning to a standstill, the calcium cyanamide is extracted from the retorts iii the form of a hard cake and cooled while the air is excluded. It is then ground into a fine powder and is ready for use. Nitrogen - 777 --t Flue FIG, 3.-DIAGRAM OF A LIME NITROGEN PLANT. During thc last year a new electric furnace has been developed for treating carbide with nitrogen, and is being universally adopted by all the new cyanamide factories in preference to the older retorts. This process is cheaper toinstall and to operate where the cost of power is low compared with that of the retort furnaces just described ; and notwithstanding that the average life of the retorts has been greatly prolonged, the new electric furnace is cheaper to maintain, possessing practically an unlimited life. Crude nitrolim contains about 57-63 per cent.of the pure cyanamide of calcium, so that its total contents in nitrogen will amount to roundly 20-22 per cent., the same as sulphate of ammonia. The material contains besides this about 20 per cent. of calcium oxide, 7-8 per cent. of silicious acid, iron oxide and alumina, and 14 per cent. of carbon, which imparts to the product its characteristic slate-black colour.Most carbide works obtain at the present time a yield of two tons of carbide per kw. year, and two tons of carbide will combine with practi- cally 500 kilograms of nitrogen in the form of nitrolim ; a power of two kw. or 2% horse-power is required per year for fixing one ton of nitrogen by the Frank-Car0 process. In addition thereto, about 5 horse-power is required for grinding and all other operations, If, therefore, it were pro-IN THE PRODUCTION OF CALCIUM CYANAMIDE 109 posed to substitute nitrolim for the nitrate of soda at present consumed in the world, it would require plants disposing of no less than 800,000 horse-power to do so. It goes without saying that before the process of making nitrolim could be developed on an industrial scale, its value as a fertiliser had first to be ascertained.And as it naturally took a number of years to complete the exhaustive agricultural researches instituted for this purpose sufficiently to make them conclusive, it will not surprise you, gentlemen, that it was only about three years ago that the question of putting up industrial works was attacked. About that time the Cyanid-Gesellschaft, in conjunction with two important Italian companies chiefly interested in the manufacture of calcium carbide, promoted, under the management of Cav-Morani, the founder of the Italian Carbide Industry, the Societa Generale per la Cianamide in Rome. The first plant on a large industrial scale was started about two and a half years ago at Piano d’Orta in Central Italy (Figs. 4 to 8), near to the Adriatic Sea, for a yearly production of 4,000 tons of lime nitrogen, and is just now being enlarged to a capacity of 10,000 tons.In addition to this, the Societa Generale is also about to appropriate a large water-power it owns in Italy for the erection of other works. One is ready to start in Terni in connection with the large carbide factories there, and another factory is in course of erection in San Marcel in the Val d’Aosta. There are at present in Austria-Hungary important cyanamide works in course of erection, all promoted by the Societa Generale of Rome. In Sebenico, in Dalmatia, at the carbide works one is being built for an initial yearly production of 4,000 tons. At Fiume, in Istria, works are also in construction for a similar output. At the present time a water-power installation of at least 50,000 horse-power is being erected at Almissa, also in Dalmatia, for the manufacture of this new artificial manure.The market for the products of these works will be the Balkans, Asia Minor, and Egypt, where, owing to the practice of irrigation, nitrolim will be of special value to agriculture. In France, the Soci6tk Francaise des Produits Azotks installed works a few months ago at N5tre Dame de Briancon (Haute Savoie), for the manu- facture of cyanamide, with an output of about 4,000 tons per annum. In the Rhone Valley in Switzerland the Sociktk Suisse des Produits Azotks has just opened equally important works. In Germany, the works at Westeregeln and Briihl on the Rhine are manufacturing 10,000 tons of nitrolim annually.It is interesting to mention that the works at Briihl for the preparation of carbide do not employ water-power, but produce the power required in the works themselves, using cheap coal in large quantities for this purpose. Another installation is that of the Brandenburgischer Carbidwerke for the preparation of nitrolim with an output of 2,500 tons per annum, near Bromberg, in North Germany, which is also completed, while the large works of the Cyanid Gesellschaft for an output of over 15,000 tons of nitrolim at Alz-Fluss, in Bavaria, are at present in construction. In the United States of North America the American Cyanamide Company has taken up the manufacture of nitrolim, and are constructing on the Canadian side of the Niagara Falls works of a present capacity of from 5,000 to 6,000 tons per annum, to be enlarged later to an output of 40,000 tons.It is quite natural that English enterprise should have given this new artificial fertiliser considerable attention. The North-Western Cyanamide Co., Ltd., with a capital of ; G I z o , o ~ , was incorporated in the middle of 1906 to acquire from the Societa Generale and work licences for the manufacturen o THE UTILISATION OF ATMOSPHERIC NITROGEN and sale of cyanamide in a vast territory comprising the United Kingdom, the Colonies, Protectorates and Dependencies (excepting Canada and Egypt), and a large portion of the North-West of Europe, viz., Norway, Sweden, and Belgium, with 30 per cent. of the consumption of Denmark, Germany, and Holland.The Sun Gas Company, now widely known as the Alby United Carbide Factories, Ltd., and their able Board of Directors, Mr. Albert Vickers, Sir Vincent Caillard, Mr. A. E. Barton, and others, took a leading part, with the co-operation and assistance of the Societa Generale of Rome, in the promotion of the North-Western Cyanamide Co., the Alby Company under- taking the erection of a new factory adjoining to that of the North-Western Company to supply them with the requisite carbide. These works, erected at Odda, which is situated at the head of the beautiful Hardanjer Fjord (Figs. 9 to 11), you will see in the accompanying picture, which shows the carbide works and the adjoining nitrolim works, which are the largest at present constructed.The capacity of the cyanamide works at present is 12,500 tons of nitrolim, and is laid out so as to be eventually enlarged to 50,000 tons. The nitrogen is produced by the largest Linde pump ever erected, with a capacity of 375 cubic metres (13,244 c. feet) per hour, and the latest electrical furnaces are there installed. The author wishes to point out here that the works at Odda, which produce 2,500 tons of nitrogen, only employ from 5,000 to 6,000 kw., whereas from the statement of Mr. Eyde' it appears that in the works at Notodden, in Norway, for the preparation of an equivalent amount of nitrogen in the form of nitrate of calcium, 25,000 kw. are required. In order to complete the review which the author has made of the works already erected for the preparation of nitrogenous fertilisers, it should be stated that the allies of the British in the Far East, the Japanese, are erecting in the south of the Kinskzu Island a works capable of producing 4,000 tons per annum, so that the manufacture of the new fertiliser will soon be localised all over the world. At the end of the present year works for a total production of over 45,000 tons of nitrolim will be in full swing, and in the course of next year there will be a correspondingly large increase in the means of production of this product. Though these figures may appear relatively high, they are quite diminutive in comparison with the continual increase in the demand for nitrogenous food for our agriculture, which in Germany alone at the present time shows an annual increase of 15,000 tons of nitrogen, which would, in the form of nitrolim, require a production of 75,000 tons.It would be an error to assume that the competition of calcium cyana- mide on the fertiliser market with Chili saltpetre, sulphate of ammonia, or Norwegian saltpetre can take on the character of a war of annihilation,as was the case with artificial indigo in respect to the natural product, On the contrary, Industry and Agriculture will welcome increasingly large supplies of nitrogen, tending to prevent the rising in the prices of the nitrogenous foods required for the development of plant life. It will be an especial satisfaction to you, gentlemen, to be assured that just at the present juncture discoveries in the field of electrochemistry have made it possible to succeed in the attempt to supply vegetation with its most valuable food, and that in the future the increasing demands for this form of nutrition by agriculturists can be satisfied, and mankind will, for the future, be able to manufacture unlimited bread and strength.Extract from the Archives of the Deutschen Landwirtschaftssrats, 3rd year, 1908.I N THE PRODUCTION OF CALCIUM CYANAMIDE 111 APPENDIX NO. I. SOME COMPARATIVE RESULTS OF THE APPLICATION OF " NITROLIM ' I TO CROPS. Spring Wheat.-Manuring experiments carried out by Professor Vincenti, of Ancona. Cwts. I. Manure applied per acre, superphosphate . . . . . . . . . 4'78 Non-nitrogenous manure as sulphate of ammonia . . . . . . . . . 0'79 non-nitrogenous ... { potassium sulphate .. . . . . . . . 1-59 above, plus nitrogenous i Chili saltpetre.. . . . . . . . . . . 0'40 Yield per acre : Grain, 9-56 cwt. ; straw 18.01 cwt. See Fig. 12. 11. Non-nitrogenous manure applied same as above- Plus nitrogenous nitrolim . . . . . . . . . . . . 1.36 cwt. Yield per acre : Grain, 9-56 cwt. ; straw, 18.17 cwt. See Fig. 13. Wiiztcr Wlzeaf.-Manuring experiments carried out by Professor Wagner, 111. Average of three years' crops in parallel experiments on areas of one of Darmstadt . hectare each, and identical applications of nitrogen. YIELD PER ACRE IN CWTS. Grain . . . . . . 10.20 16-77 16.34 16.89 So Manure. Chili Saltpdre. Sulphate of Ammonia. Nitrolim. Straw . . . . . . 20'64 37-21 34'43 35-06 With Chili saltpetre . . . . . . . . .. . . 2 4 6 With sulphate of ammonia . . . . . . . . . 2 5 4 With nitrolim . . . . . . . . . . . . . . . 2 19 14 PROFIT PER ACRE COMPARED WITH UNMANURED. s. d. See Fig. 14. IV. Wzizier Rye.-Manuring experiments carried out by Professor Wagner, of Darmstad t. Grain Straw YIELD PER ACRE IN CWTS. No Manure. Chili Saltpetre. Sulphate of Ammonia. Nitrolim. . . . . . . 7-01 15-38 15-30 15-06 . . . . . . 12-51 26.86 28-61 26.38 PROFIT PER ACRE COMPARED WITH UNMANURED. s. d. With Chili saltpetre . . . . . . . . . . . . I I I I I + With sulphate of ammonia . . . . . . . . . 2 6 I I $ See Fig. 15. With nitrolim . . . . . . . . . . . . . . . 2 5 82 V. Oak-Manuring experiments carried out by Professor Wagner, of Darm s tad t . YIELD PER ACRE IN CWTS. No Manure. Chili Saltpetre.Sulphate of Ammonia. Nitrolim. Grain . . . . . . 6.13 Straw . . . . . . 15.38 13.31 23'43 13-15 23'39 13.31 2 5 . ~ 8IIZ THE UTTLISATION OF ATMOSPHERIC NITROGEN PROFIT PER ACRE COMPARED WITH UNMANURED. .& s. d. With Chili saltpetre . . . . . . . . . . . . I 2 8 With sulphate of ammonia 1 4 3; With nitrolim 1 9 1% . . . . . . . . . . . . . . . . . . . . . . . . See Fig. 16. VI. Indian Cortz.-Manuring experiments carried out by Professor Menozzi, of Milan. COMPARISON OF EQUAL QUANTITIES OF NITROGENOUS MANURES-YIELD PER ACRE I N CWTS. Manure Used. Grain. Stalks and Leaves. ... 61.76 40 per cent. sulphate of ammonia 60 per cent. Chili saltpetre 1 . . . . . . f 28.61 See Fig. 17. . . . . . . . . . . . . . . . Nitrolim 29'25 57'78 See Fig. 18. VII. Potatoex-Manuring experiments carried out by Professor Steglich, of Dresden. Manure containing 674 lbs.of nitrogen per acre in the form of Chili nitrate, sulphate of ammonia, and nitrolim was applied. Preliminary manuring consisted of 44% lbs. phosphoric acid in thc form of 18 per cent. superphosphate and ++Q Ibs. of pqtassium monoxide in the form of potassium chlorate, and besides the equivalent amount of calcium cyanamide 12 cwt. of carbonate of lime were added. With Preliminary Chili Sulphate of Manures. Saltpetre. Ammonia. Nitrolim. Cwts. per acre . . . . . . 40.80 48.6 I 43'83 46.36 See Fig. 19. VI I I. Sugar Beet.-Manuring experiments carried out by Professor Strohmer, of Vienna. 468 lbs. superphosphate. 224 lbs. of 40 per cent. potassium salts. Preliminary manuring, per acre ...{ 1-35 cwt. sulphate of ammonia. 1-38 cwt. nitrolim. Nitrogenous manures, per acre ... { 1-78 cwt. Chili saltpetre. CROP I N CWTS. PER ACRE FROM THREE PARALLEL EXPERIMENTS. No Manure. Chili Saltpetre. Sulphate of Ammonia. Nitrolim. Roots . . . . . . 215.96 278'13 255'41 286'49 Sugar . . . . . . 36.10 47'43 43'72 50.08 See Fig. 20. APPENDIX NO. 11. GENERAL DESCRIPTION OF THE WORKS OF THE NORTH-WESTERN CYANAMIDE COMPANY, LIMITED, AT ODDA, NORWAY. As the works of the North-Western Cyanamide Company are the largest of the kind so far erected it will be of 'interest to give some details in connection therewith. Site.-This was chosen because of its proximity to one of the more abundantFIG. 4.-Piano d’Orte. General View of Works:FIG. 5.-Piano d'Orte.First Operation-receiving Carbide. FIG. 6.-Piano d'Orte. Manufacture of Nitrogen Gas.FIG. 7.-Piano d’Orte, Filling Charging Cylinders with Carbide, FIG. 8.-Piano d’Orte. Discharging Retorts.FIG. Io.-Odda Works, Interior of Furnace Room. FIG. II.-Odda. Inside Storage Lager.Odda Village. Cyanamide Works. FIG. g.-Odda. General View of Harbour, Village, North-Western Cyauainide Works, and Alby United Carbide Factories’ Works, Carbide Works. VOL. IV-T6FIG. 12.-Spring Wheat. Effect of Chili Saltpetre. (Professor Vincenti). FIG. 13.-Wheat. Effect of Nitrolim (Professor Vincenti). VOL. IV-T7Without Nitrate of Sulphate of Calcium cyanamide manure. soda. ammonia. (nitrolim). FIG. 14.-Comparative Results on Winter Wheat (Professor Wagner). Without Nitrate of Sulphate of Calcium cyanamide manure.soda. ammonia. (nitrolim). FIG. 15.-Comparative Results with Winter Rye (Professor Wagner).Without Nitrate of Sulp h ate of Calcium cyanamide manure. soda. ammonia. (nitrolim). FIG. 16.-Comparative Results with Oats (Professor Wagner). FIG. 17.-Indian Corn. With 10 per cent. Nitrate of Soda and 60 per cent. Sulphate of Ammonia. FIG, ~$.--Indian Corn with Nitrolim.Fundamental Nitrate of Sulphate. of Calcium cyanamide ammonia. (nitrolim). manuring. soda. FIG. ~g.-Comparative Results with Potatoes (Professor Steglich) Without Nitrate of Sulphate. of Calcium cyanamide manure. soda. ammonia. (nitrolim). FIG. 2o.-Comparative Results with Sugar Beet (Professor Slrohmer).I N T H E PRODUCTION OF CALCIUM CYANAMIDE 113 and less expensive sources of water-power to harness in Norway, situated in the valley of Tysse, between six and seven miles from the southern end of the Hardanger Fjord, and because suitable level land of sufficient extent for factory purposes existed abutting on the fjord to the east and south of the village of Odda.Power.-The harnessing of the natural water-power available in the Tysse Valley under agreement with the Alby United Carbide Factories, Limited, was undertaken by the Norwegian Tyssefaldene Company some two years ago. This Company also provided the land adjoining the village of Odda now occupied by the two companies. The power is derived from the last of the small chain of lakes in the Tysse Valley connected by the Tysse River, and fed from glaciers situated some ten miles from the eastern edge of the Hardanger Fjord. This lake is supplied from several lofty natural falls, the chief of which is the well-known Skjceggedalsfal.The water for power pur- poses is taken at about 40 ft. under the surface of the lake at its lower end, where a drowned dam has been constructed, enters a tunnel some three miles in length driven through the intervening hills, and is delivered to a series of 6-ft. pipes laid on the surface of the cliff overhanging the fjord. The generating station is built at the fjord level where there is an effective fall of 1,350 ft. upon the turbines. The permanent works, such as the tunnel, &c., are constructed for an eventual output of 80,ooo electrical horse-power, but the present installation is for the delivery of a quarter of that amount.Area Occupied by the Works.-The North-Western Cyanamide Works and those of the Alby United Carbide Factories, which supply the former with the raw material for the manufacture of their “ nitrolim,” occupy an area of some 34 acres exclusive of land on which their respective workmen’s villages are erected, the works of the N.W.C. Company occupying from 6 to 7 acres. OutpuL-The cyanamide works are designed for a yearly output of some 12,500 tons of a product testing between 20 and 22 per cent. of nitrogen. The carbide works are intended for an initial output of over 30,000 tons, and both works are laid out so as to be readily and progressively extended to four times their present capacity.BuiZdiizgs.-The main buildings of the cyanamide works occupy an area of 38,000 sq. ft., and consist of a suite of buildings comprising the carbide crushing house of three storeys, the electric furnace-room, the cyanamide crushing house of two storeys, the storage hoppers, with the cyanamide aerating-room on top with a storage capacity of some 8,000 tons, the packing- room, with the following isolated additional buildings : the Linde house, the transformer house, the repairing shops and store, and the drawing and general offices and laboratory. Works Comections.-An electric tramway connects the carbide and cyana- mide works and places them in communication with an extensive store at the export wharf, where two large ocean-going steamers can be berthed at once. The carbide works possess in addition an import quay, situated on the east side of the Odda River and connected with their works by an overhead cable- way, by-means of which the supplies of coal and limestone are delivered at the kilns, and the Cyanamide Company possess a short-length cableway connecting the furnace-rooms of the Alby Company with the upper story of the carbide crushing-room.Manufacturing Process.-The carbide broken into lumps received from the carbide works is delivered on the floor of the upper story of the carbide crushing house. There it is fed into a first set of crushers, traversing an intermediate set of crushers on the first floor, and thence passes through a double set of mills, where it is ground to the degree of fineness required, T8114 THE UTILISATION O F ATMOSPHERIC NITROGEN The whole of these operations are effected automatically with a special plant, which is entirely air-tight.From the fine grinding mills the carbide powder falls into a closed hopper under floor-level, from which the automatic lifting and conveying machinery delivers it into the furnace-feeding hoppers. The carbide power is then delivered into the recipients for the electric furnaces, of which there are 196 in the furnace-room, constructed for 300-kg. charges. These recipients are lifted and transported by an overhead electric traveller, and dropped into their respective furnaces in the furnace-room. The lids are then put on, fastened down, and rendered air-tight. Nitrogen gas is admitted under pressure. The alternating current is switched on, and the temperature of the contents raised to some 800' to 1,000' C.The whole process of converting the carbide into cyanamide takes on an average forty-five hours, including cooling. The movable recipients are lifted out, and their contents when cool are delivered into a double set of rnills in the cyanamide crushing-room, where they are once more reduced to a fine powder, which falls into hoppers below floor- level, and is lifted and delivered at the height of about 60 ft. on the floor covering the storage hoppers. Here it is fed into long, slow-moving conveying worms, over which is a trunking through which a current of air passes, travelling in the opposite direction to the conveyers. From the aerating conveyers it is distributed and dropped through openings into the storage hoppers, which are arranged on the unicellular system. From the hoppers the cyanamide is drawn, when required, through central horizontal sluice openings at the bottom of the hoppers communicating with conveyer pipes provided with endless worms, delivering into hoppers, from which it is lifted and fed into the tanks supplying the automatic weighing and sack-filling machines in the packing house. The whole of the plant above described has a maxiniuin capacity of some 30 tons Cyanamide per working day. The most important auxiliary building is the Linde house, where a complete plant duplicated in all essential parts for a production of 375 cubic metres of practically pure nitrogen is installed. This plant is too well known to require description, but it embodies all the latest improve- ments which the accumulated experience of many years has taught the patentees and makers to be desirable. The nitrogen as generated is dis- tributed through control metres to the various plants using it throughout the works without intermediate storage. There are also separate houses for the oil-cooled transformers (English make) of the total capacity of some 2,000 kw., which transform the current delivered by the generating station from 11,000 volts to the working pressure. The repairing workshop and store is provided with a smithy and a complete plate-bending, riveting, and cutting plant for the repair of the electrical furnace and various machine tools. The offices and laboratory are a large and convenient building of two storeys, with rooms for the manager, chief chemist, &c., on the upper floor, and areadjacent to a similar building belonging to the Alby Company at the road entrance of the works. The workmen's village is situated on the west side of the works at about half a mile distance, and accommodation is provided there for some forty families. Separate buildings for the accommodation of the other members of the works staff and foremen are also provided.