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T H E JOL7RAVALOF I N D U S T R I A L A.YD EL\-GIi\-EERIlVG
Blount as 8.6 kilowatt hours per kilogram. Artificial graphite is another electric furnace product, made by heating amorphous carbon to a high temperature. For the two latter substances we are indebted to Dr. E. G. Acheson. In the employment of the electric arc for chemical manufacture we have the crowning achievement in electrochemical work-the fixation of atmospheric nitrogen and the synthesis of nitrates. The importance of this warrants my dwelling on it somewhat in detail. I n the first place, combined nitrogen is absolutely essential to life. Nitrogen compounds are found in protoplasm, that part of the cell where the life process goes on. Only a few organisms, certain bacteria, are capable of taking free nitrogen and combining it. Consequently the higher forms are dependent upon the lower for nitrogen compounds. This source of supply is, in this day of intensive agriculture, inadequate and hence the use of fertilizers containing nitrogen. Compounds suitable for this purpose are found native in but few places 0.n the globe. They are chiefly nitrates of sodium and potassium and occur most abundantly in South America where the Chili nitrate kings are waxing wealthy on their monopoly. I t requires no great foresight to see that these deposits would in time become exhausted and the problem of artificial nitrates began to attract scientific attention years ago. After much study and many experimental failures, the puzzle was solved, thanks to electrochemistry. I t was known for a long time that electric sparks in the air caused small quantities of nitrogen and oxygen to combine. This was the starting point, and experiments were directed to increase the efficiency of the reaction. At the arc temperature of 30oo0C. considerable oxide of nitragen will be formed but the decomposition a t high temperatures is great also. The problem of securing increased yield was largely one of sudden cooling of the gases after leaving the arc. One of the first devises, from which much was expected, involved many arcs of small energy content. The arrangement was too complex and was finally given up. About the beginning of the last decade the matter was again tried out by two Norwegian inventors, Birkeland and Eyde, who succeeded in devising a workable plant in use to-day. They employ a strong current and large arc which is drawn from side to side b y means of an electro-magnet. The vibrations of the arc permit contact with a large volume of air. The immediate product of the arc is nitric oxide, part of which oxidizes to nitrogen peroxide on coming in contact with the air. The mixed gases are washed by water, forming a solution of nitrous acid and nitric acid. Nitrates are made from the acid by treating with Or lime' The process is successful and a t Notodden, Norway, there is a factory using 30,000 h. p. It remained for the Germans, however, to simplify the method further* Dr' Schoenherr' to whom I am indebted for some of the details of this industry,
CHENISTRY.
Mar.,
1911
employed by the Badische Anilin and Soda-Fabrik, was largely responsible for this advancement. His study of the problem resulted in discovering a method of using a stationary, continuous arc acting on a current of air blown spirally around it. His company has a n experimental plant a t Christiansand, Norway. They have 1300 kw. feeding three furnaces with 600 h. p. each, under a tension of 4200 volts. The arc produced is about 5 meters long. The furnace, according t o Dr. Schoenherr, consists essentially of an iron pipe in upright position. I n the lower end is a n insulated electrode. The upper end is water-cooled. Near the lower end are openings to permit air to be blown in tangentially. A short arc is struck between the electrode and the side of the pipe. The air current then carries one end of the arc up the side of the tube until it terminates on the upper, water-cooled end. The result is a long flaming arc surrounded by a whirling current of air. Instead of forcing cold air directly into the arc, it is given a preliminary heating by allowing it to enter a n outer pipe and traverse the length of the arc tube t o the tangential openings. The gases coming from the arc are cooled to about 1200' C. before leaving the tube. As the temperature sinks lower the nitric oxide takes up oxygen from the air and becomes peroxide. The gases are absorbed by milk of lime forming calcium nitrate and nitrite which, according t o several authorities, is quite as suitable for use as a fertilizer as the straight nitrate. This, in brief, is the history and present status of the artificial nitrate industry, which is destined t o become one of the chief factors in future civilization. The whole present electrochemical activity is, to my mind, the mere beginning of a work pregnant with possibilities for the electrochemical technologist. Much of the work requires great expenditure of power which must therefore be cheap, but this should be no deterrent since but a small fraction of the world's water-power is now utilized. I n closing, the facts seem to warrant the conclusion that in present-day general engineering, a knowledge of the chemistry of materials is of considerable service, and that the demands of the future in this respect will be probably still more urgent; also that in the electrical department, there is rapidly opening up a field of activity where engineek with special chemical training will find many 0ppor;tunities for the exercise of chemical and mechanical ingenuity. THE THEORETICAL BASIS FOR THE USE O F COMMERCIAL FERTILIZERS.' By FRANK K . CAMERON.
The recent trend of events in this country makes especially important the problem of fertilizers, which must be met wisely if use is to be made of that great national asset, the soil, Much is being brought to light regarding the of supply, the results of field tests, etc. I t is the purpose of this paper to state the case in a way which, i t is believed, 1 Abstract of remarks made before t h e Division of Fertilizer Chemists, a t the Minneapolis Meeting. Published b y permission of the Secretarv ~ ~ ~ i ~ ~ l ~ ~ ~ ~ .
.
ADDRESSES. makes clearer the problem, the method of attack available to the scientist, and the correct attitude of the fertilizer producer. From an agricultural standpoint, the soil may be defined as that portion of the land surface adapted to the support and growth of a crop plant or plants. I t is a system of many components, mineral and organic, and contains living organisms. The material remnants and detritus of nearly if not all activities on ,the solid portion of the earth's surface find their way to the soil, and by various transporting agencies, especially mater and wind, are carried from soil to soil. Not only the number but the relative proportions of the various components vary quite widely in different soils. Moreover, every component of the soil is continually involved in processes of change. Therefore each soil is a dynamic system, with a complex summation of properties ; I consequently it is highly individuated; no two soils can be expected t o be exactly alike, nor any one particular soil to remain just the same from time to time, either in crop-producing power or response to cultural methods. Each soil must be regarded as a distinct entity, with .its own properties ; but these properties are continually being modified as a result of activities within the soil as well as by natural and artificial agencies from without. K i t h these considerations in mind the theory of soil management or control can be easily formulated. For further simplicity a mathematical terminology can be employed, it being clearly understood, however, that no mathematical ideas are implied other than those explicitly stated. Crop production (C) is dependent upon: the biological the amount and peculiarities of the plant or crop (P); distribution of the rainfall ( 7 ) and' the sun's energy ( s ) ; the properties of the soil, physical ( p ) , chemical (c) and biological ( b ) ; and upon other factors, the number being yet uncertain b u t probably large. Besides these natural factors, a cultivated crop is dependent upon artificial methods of control which fall conveniently into the three classes, tillage methods ( T ) , crop rotations ( R ) , and fertilizers ( F ) . This dependence may be expressed as follows : C = f 7 ( P , 7 , s , p , c b, . . . . . . . . T , K , F ) What the nature of this function may be, no one yet knows. I t has generally been assumed that i t is simple, and by many investigators, that it is a linear function. It is reasonably certain, however, t h a t i t is quite complex, and certainly i t is not linear as is shown by the accumulated results of plot experiments. T w o methods of attacking this function suggest themselves. Suppose the different factors are independent variables. Then, obviously, the proper experimental procedure is to keep all but one constant, and varying that one, to meas,ure the effect b y the crop produced. This is the method which has generally been attempted by agricultural investigators, as in the popular plot tests for fertilizers and in THIS (1910).
JouRs.~L,
1, 806
(1909); J . Phj's. Chem., 14, 320 and 393
189
greenhouse cultures. ,4n enormous amount of d a t a has been accumulated, but the results have been disappointing. If the assumption of independent: variables were valid, it should be comparatively easy to determine the nature of the function; and if, in addition, the function were linear, fertilizer effects, for instance, should be additive. The evidence shows fertilizer effects to be generally (though not always) cumulative, i. e . , three constituents are more effective than two, and two more effective than one.' But the effects are not additive, the effects of a mixed fertilizer being sometimes greater, more often less, than the sum of the effects produced by each component separately. As stated above, the nature of the function is yet undetermined. Consideration of the large mass of experimental evidence that has been accumulated in the field and laboratory leads inevitably to the conclusion that all the factors in crop production are dependent variables. Altering the chemical properties (6) for instance always affects the physical properties, the biological properties. the distribution of moisture, etc. Tillage obviously changes the physical properties of the soil; i t necessarily affects the bacteria and other biological factors in the soil, the chemistry, organic as well as inorganic, presumably the functioning of the plant, etc. Concrete example is furnished by the addition of potassium carbonate ( F ) to a loam soil. The factor c was increased, but the soil was deflocculated and somewhat puddled, p being decreased : the growth of desirable bacteria was inhibited, with presumably an increase in undesirable kinds, thus decreasing b ; and without attempting to follow the effects on the, other factors, it may be said that the summation of these several results as expressed in crop yield ( C ) was a decrease. Recognition that the variables in the function representing crop production are dependent suggests the second method of attack, namely, to attempt the substitution of each variable in terms of some one.2 Experimentally this is difficult and perhaps not actually susceptible of complete accomplishment. I t is practicable, however, to do much in this direction. Clearly, a mere measurement of crop production can not in itself furnish much information. If the plot experiments with fertilizers of the future are to be of any real assistance, observations must be made upon the physical and biological properties of the soil, a t least throughout the growing season. Not only the yield of crop, but the character of the yield, the particular life history of the crop must be recorded. More important a t the present time perhaps is the determination of the kind and degree of the changes produced in different variables by the changes in any one of them. This mode of procedure is absolutely essential if a rational system of soil management is t o be developed. Bureau of Soils, r.S. Dept. Agriculture, Biclls. 58, 62, 64, 66, 66, 67.
I t hardly seems necessary t o state t h a t this does not imply t h a t , in practice. fertilizers can t a k e the place, or perform the functions of tillage or mop rotation. It can not be too strongly emphasized t h a t good farming requires the employment of all three methods of control.
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T H E J O U R N A L OF I N D U S T R I A L A N D E-VGINEERING C H E M I S T R Y .
Confining attention to that artificial factor most ,easily controlled b y man, several important conkiderations must be noted. T.here is now existing a considerable mass of ex‘perimental evidence supporting the general view outlined above. I t is known that definite organic sub‘stances are present in soils,‘ some of which are toxic ‘to various plants, and that the addition of fertilizer salts modifies the toxicity or inhibiting influence, a n d i t has been shown that these modifying influences are specific. I t is known that oxidizing processes on the one hand and reductions on the other, produced b y organic substances, enzymes, bacteria, and probably inorganic substances, are normally taking place in every soil which more or less affect the adaptability of that particular soil for different crops; and i t has been shown that these oxidations and reductions are markedly affected by the addition of inorganic salts in commercial fertilizers. And so far as the available evidence goes, again the activities of these salts are specific.? It has been shown that the activities of bacteria and lower plant forms in the soil are much influenced by the salts in commercial fertilizers, and these activities are very potent in determining the growth of higher crop plants. The mechanical properties of the soil and the physical properties of the soil solution, as in its density, its movement through the soil, and other phenomena of importance to crop production, are affected by soluble salts. The absorptive power of the soil towards the different salts and their various constituents is now recognized as of very great importance in determining the relationships to crop yield. The addition of a salt may sometimes influence their absorptions, as in the case of a soluble nitrate lessening the absorption of phosphoric acid,s ,with marked result in the crop. And i t has been shown that the addition of salts has a measurable influence on the optimum water content, and the many physical properties of the soil dependent on the water content.4 It is well known that flocculation or deflocculation is affected by exceedingly small proportions of salts; thus “crumbing” of the soil and its tilth can be markedly affected by the addition of fertilizer^.^ The hitherto popular notion that these physical effects are of minor importance is due mainly to the fact that investigators have not known what observations were necessary nor how to measure them. But without going into detail here, it may be said that the physical effects of fertilizers on the soil are now known to have an importance for crop production which can no longer be slighted. Numerous water culture and other experiments leave no doubt that fertilizers directly affect the functioning of the plant, as well as influencing it through their effects on the Soil, and this fact needs no further exposition here. While the lines of investigation covering the various I
Bureau of Soils, U. S. Dept. Agriculture, BuZl. 53. I b i d . , Bull. 73. 3 Enpublished experiments by H . E. Patten. 4 Unpublished experiments by R . 0 . E . Davis. See also Bull. SO, Bureau of Soils, U. S. Dept. Agriculture. J . Frank. Inst.. 169, 421-38; 170, 46--57 (1910). 2
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Mar., 191 I
kinds of effects produced by the constituents of commercial fertilizers are as yet hardly more than initiated, they have nevertheless progressed sufficiently to leave no manner of doubt that fertilizers in Some way and to Some extent influence each and every known factor affecting crop production. Obviously no simple explanation of the value of fertilizers can be correct, but all the possible effects on the various factors influencing crop production must be considered. Consequently no simple procedure for examining soils, such as the analysis of a n acid extract, can in itself be expected t o furnish a satisfactory idea of the productivity of a soil, or its fertilizer requirements ; a much more comprehensive analysis of the soil conditions is necessary together with a knowledge of the crop factors; and for an intelligent utilization Of the soil, t o develop its best commercial efficacy, there must also be known the economic factors affecting the growing, shipping, and marketing of the crop or crops. These latter factors, while often regarded as outside the province of the soil expert, can not be disregarded in the larger considerations Of the subject* One economic consideration suggested by this view of fertilizers has hitherto escaped consideration, although of enormous importance to this country. The annual expenditure for fertilizers in the United States is Probably not’ f a r from $ I ~ O , ~ O O , O O O , of which it is safe to say 80 per cent. is spent in the South Atlantic States and less than 5 Per cent. is spent in the trans-Mississippi States. And this condition of the fertilizer industry is accepted with apparent Placidity Under the influence of the Prevalent notion that fertilizers are Of value only for the mineral Plant foods they contain, and the further idea that the soils of the eastern states and especially Of the southern states are “WOIYI o u t ” and depleted Of available plant food.’ The western States, on the contrary, because they have less recently developed are supposed to be still rich in Plant foods, and this notion is supported, speaking generally, b y intense local pride, denying the value of fertilizers for fear it will appear an admission that the local soils are wearing out and becoming less productive than those of neighboring areas. Yet the Production of our staple crops Per acre is higher in the older than in the newer states. I t is a widely accepted opinion in Europe that, fertilizers pay best on the “richer lands,” and this appears to be the view of those consummate farmers of the Occident, the Japanese, who have a Popular saying to the effect that the way to ruin a farmer is to put him on virgin land. There is no real evidence that per se the soils of the eastern states are inferior in crop-producing ability to the soils of the more recently settled west, but if it were true, the idea of complex fertilizer effects, and the nature of the function representing crop production, would lead t o the conclusion which has strong support in the more highly developed agriculture of Europe and the Occident, namely, that fer“Regarding the Supply of Mineral Plant Nutrients,” see J . P h y s . Chem., 14, 356 (1910).
-4D D RE S S E S. tilizers should prove more profitable on the better soils. With the rapid occupation of all available land, rise in land values, and the necessary introduction of more intensive methods of cultivation, the time is a t hand if i t has not already come, when the western agricultural states should be the greatest consumers of commercial fertilizers. That this important development should much longer be retarded if not blocked b y popular adherence to a n unscientific and antiquated theory is inconceivable, yet one finds not only some agricultural investigators, but even some fertilizer chemists still clinging t o it. The difficulty which seems t o have the most significance for the rigid advocates of the older theory of fertilizer action is the supposed fact t h a t only those fertilizers are effective which contain potassium, phosphorus (as phosphates), or nitrogen, and the question is seriously asked: why, if these ideas are correct, cannot sodium chloride be used in place of the more expensive potassium salts? The answer however is quite clear. I t is no more reasonable t o expect sodium chloride to produce the same effects that potassium chloride does than it is to expect these same effects from a soluble phosphate. Each salt has its own specific properties and must be expected t o produce effects which differ in kind as well as degree ; and this quite apart from the facts that there is some evidence favoring the view t h a t sodium can partially a t least replace potassium in the mechanics of plant metabolism,I and t h a t i t is recognized b y every one t h a t under the conditions of plant growth as we know them, the presence of potassium in the cell sap is essential t o plant' growth and the presence of sodium is not. As a matter of further fact, sodium chloride has sometimes been used a s a fertilizer and in general with about the same kind of success t h a t has followed the use of other soluble salts, namely, in a majority of cases there was a more or less satisfactory increase of crop production. Whether or not sodium chloride should have a place among the standard fertilizer salts is b y no means a settled question, and time and further experience with it are needed. I t has the essential requirements of a commercial fertilizer, in t h a t it affects plant growth, under proper conditions favorably, it is obtainable from a ,large and permanent source of supply, and is cheap. Moreover, i t is about the only substance meeting these requirements t h a t is not generally- in use as a fertilizer. If future experience should show t h a t i t is not a useful soil amandment it will certainly be for other reasons than that it does not contain a recognized plant food. I n this paper, i t is pointed out that: I. Crop production is the result of many factors, natural and artificial, and these factors are all mutually dependent. 2. KO simple theory of fertilizer action can satisfactorily account for the known facts. 3. With intensive methods of cultivation, fertilizers are effective on all kinds of soils, and are the more efficient on the naturally better soils. See, for instance, t h e work of \\-heeler and his colleagues, Repovt o i the Stafe Erfieriment S i a f r m of Rhode Island, 1894 to 1909.
4. Other materials than those containing the traditional plant foods may yet become valuable fertilizers, if they satisfy commercial requirements. BLEACHING WITH SODIUM PERBORATE. B y J MERRITTMATTHEWS, PH D.
Though sodium perborate, as well as other salts of perboric acid, have been known to the chemist for some time, i t has only been within the past year or two t h a t their use has been put fqrward for purposes of bleaching. The chief salt which is available for this purpose is sodium perborate, though magnesium perborate has also been employed. Sodium perborate is a substance similar t o sodium peroxide in t h a t i t has a considerable amount of loosely combined oxygen, which under proper circumstances is readily liberated from combination in the nascent state, and thus becomes available for use in bleaching. Sodium perborate has been principally exploited in Germany during the past few years, where its use for various purposes of bleaching has been the subject of quite a number of patents, though it is t o be doubted whether these patents possess any commercial value. From Germany the use of sodium perborate spread to England, where it has been the subject principal y of advertisements rather than entering into any practical use. During the past year, sodium perborate has appeared in the American market, and we believe i t is also manufactured in this country a t the present time. Sodium perborate is prepared from sodium peroxide and boric acid. As compounds derived from boron are all more or less expensive commercially as compared with compounds of sodium alone, it is reasonable to expect that sodium perborate would be more expensive than sodium peroxide when based on an equivalence of available oxygen. Furthermore, sodium perborate even in the pure condition, contains only 10.4per cent. of active oxygen, whereas sodium peroxide contains about 2 0 per cent., or practically twice as much in the same amount of c h e d c a l . In its general application to purposes of bleaching textiles, sodium perborate is very similar to sodium pergxide or hydrogen peroxide. I n fact, the various per-oxygen chemical compounds which have from time to time been suggested as capable bleaching agents, such as perborates, percarbonates, and persulphates, all depend in the final resort for their bleaching activity on the fact t h a t they readily furnish a solution of hydrogen peroxide when dissolved in water, or when their solutions are treated with a suitable acid. Therefore the bleaching process with all these reagents comes down to a question of bleaching with hydrogen peroxide. I n the consideration of this question, the chief factors to be discussed are the comparative amounts of hydrogen peroxide formed from equal quantities of the different compounds, the relative cost of the hydrogen peroxide thus produced, and whether the decomposition of the product brings into the solution other ingredients which may hinder the activity of t h e hydrogen peroxide in its bleaching efficiency.
