Elements of Physical Biology

6, W. Clarke, loc. cit., 1920, p. 52; Linck, Kreislaufvorginge, 1912, pp. 6-7. It has also been put forward (Schénbein) that a certain amount of nitric acid is formed in the evaporation of moisture from the earth (Bunge Physiological Chemistry, 1902, p. 11). But this is doubted by Ostwald. (Grundlinien der Anorganischen Chemie, 1912, p. 384. ) terized by human interference with the course of nature. It is hardly necessary to point out that such a distinction between natural and artificial agencies is merely a convenient use of brief terms; the fact must never be lost sight of that man himself is very essentially part of nature, and that his development, whether physiological, psychological, sociological, economic, or what not, is part of the great process of nature.

Human Interference in Nitrogen Cycle. Man’s earliest conscious, purposive intervention in the nitrogen cycle dates from antiquity, and primarily consisted merely in taking more or less pains, in an empirical way, that the nitrogenous waste material of animal economy be, as far as possible, restored to the soil. Perhaps the first recorded use of fertilizers not derived from current wastes of domestic animals is the exploitation of guano by the Incas, which dates from antiquity, and was brought to the notice of Europe by de la Vega in 1604. It seems to have aroused no interest until attention was again drawn to it two hundred years later by von Humboldt and by Justus Liebig, and large scale importations of guano into Europe began soon after this. A greater event in the history of agriculture was the opering up, in 1831, of the Chilean nitre beds. Without this source of saltpeter the modern development of intensive agriculture, and the consequent growth of population in all civilized countries, would have been at the least greatly hampered. The rapid rise of the saltpeter industry is clearly exhibited in table 23 and the corresponding graph figure 50.

While our chief interest here is in the agricultural use of Chile saltpeter, its consumption in the industries is altogether too extensive to be passed by without mention. J. D. Pennock’ gives the figures shown in table 24 for the relative amounts of saltpeter consumed in different uses. It should be observed that Pennock’s figures relate to peace time conditions. Even so, nearly one-half the consumption is taken up in the manufacture of explosives. Nitrogen thus employed is, of course, lost to the life cycle. A certain loss also concurs in the refining of the caliche (native saltpeter), and in the production of nitric acid and sulphuric acid’ therefrom.

"J. D. Pennock, Jour. Industr. and Eng. Chem., LOU Wea lidas * When manufactured by the Chamber process. The figures in column IJ are the Chilean nitrate production, as given by Parsons and Petit, Brokers. The figures in colums II and III, from 1831 to 1911 inclusive, represent the World’s consumption of saltpeter according to Génie Civil, vol. 62, p. 192. The figures from 1913 to 1918 in colums II and III represent the total production of Chilean and Indian nitrate, according to Grinnell Jones, Jour. Frankl. Inst., 1920, vol. 134, p. 398. The precipitous drop in the Chilean production in 1915 was due to a blockade established by the Germans during the early stages of the World War. See Fig. 50, in which circles indicate production, the drawn out curve consumption.

Distribution of Chili saltpeter consumption in the United States in 1910 among different uses RI SUTILAOUUTGVOL MOLOUIZOL oe cde bak nae << cieeis c 0's esi ule we wa sisieis 13 Immanumtacture Of dvestutis....- oss. -<b 52 ese cklcces oe der cece cere 12 Re SOUSTO! COCMWISIT Ye rene cs cnnrecede ren sree eg seen es Saanpesens 10 Tift MEN ee ansepcy decile ee COI OR Mic OM RO o eS ORO CIE 4 WESTOVER acs cet se ret pean se Apher nas cS sceko np con aes? 41 Haw laine te KA ee siya caches netic ie gehen oR Re Ie ae Ic 9 LPR DDUTIGIACLC sew dsl ein apiicaiear s+ oe vecse ures osien > hema. 6 Milan ITNGE CLOT er icine Ae eeiore ataiaae ce sh aso gor ae» : Sie ein ok mielauevage wine 5

Origin of Nitre Beds. The origin of the nitre beds is uncertain. The presence of boron in the deposits, and the association of this element with ammonia in volcanic emanations, have been regarded by some as evidence that the saltpeter is of ultimately volcanic origin. Others have ascribed it to organic sources, such as altered guano deposits. But whatever be their origin, this is certain, that the saltpeter beds represent an accumulation of ages, and that the present rapid rate of consumption is out of all proportion with the rate of formation of the deposits. In other words, here, as in the case oi coal, we are living on our capital, and must prepare ourselves for its impending exhaustion.’ It is true that our other sources of combined nitrogen—notably ammonia from coke oyens—supplement our drafts upon the nitre beds, and thus help to defer the day of scarcity. But coal itself is a limited stock, and other sources of combined nitrogen seem quite inadequate for the needs which we have developed under the stimulation of temporarily bountiful supplies. It is a peculiarity of living substance that in times of plenty it tends to grow beyond the bounds compatible with ultimate stability; it overshoots the mark so to speak; the curve along which it approaches its equilibrium is very apt to be humpbacked, or it may be oscillatory.1° The prospect of a period of actual diminution (not mere marking time) to follow upon a period of exuberant prosperity, is one that an organism gifted with foresight must look upon with disquietude. Such foresight may, then, lead an organism so gifted, to make efforts to provide for untoward future exigencies, either by laying by supplies, in times of plenty, for times of stress; or by devising means, if possible, to increase, by new measures, the supplies which, under the old régime, would presently fall short of requirements.

Man has not always made a display of brilliant foresight, but in this instance, in making ready for the exhaustion of the nitrate supply, he has taken time by the forelock, and all indications are that long before the emergency arises he will have made himself ®The probable date of this exhaustion has been variously estimated. Little value can be attached to positive statements. More significant, perhaps, is the negative report made in 1913 to the Chilean Government by the Inspector General of Nitrate Deposits: ‘There is no fear of the Chilean nitrate deposits being exhausted for two hundred years’ (Grinnell Jones, loc: cit., p. 401).

ready to meet it. For the last decade has seen the development, to full industrial capacity, of several processes for the fixation of atmospheric nitrogen, its conversion into compounds directly or indirectly adapted to enter the cycle of nomadic nitrogen. For details regarding these modern industrial developments the reader must be referred to the technical literature."' It must suffice to indicate here very briefly the nature of the several processes.

1. The Birkeland and Eyde Process, is essentially man’s imitation of the production of nitric acid by lightning. Air is passed through an electric are fanned out into a broad dise by a magnetic field. The process is commercially viable only where very cheap power is available, and has been developed mainly in Scandinavia, with the use of water power. 2. The Cyanamide (Frank and Caro) Process effects the absorption of atmospheric nitrogen by calcium carbide in the electric furnace. The product can be employed directly as a fertilizer, or can be made to yield ammonia and other nitrogen compounds.

3. The Haber Process effects the synthesis of ammonia from nitrogen and hydrogen under pressure (100 to 200 atmospheres) in the presence of a catalyst. An allied process is that of Claude, which works at very high pressure (1000 atmospheres). 4. The Biicher Process, which has not yet passed beyond the experimental stage, yields cyanides; these can also, if the market warrants it, be made a source of ammonia. A highly significant development is the union of the Haber ammonia process with the Solvay process, whereby the carbon dioxide obtained as a waste product in the manufacture of the hydrogen for ammonia synthesis, is utilized in the production of sodium carbonate; while, on the other hand, the formation of large quantities of the nearly worthless calcium chloride waste of the Solvay process, as ordinarily conducted, is avoided. Inasmuch as “soda ranks second only to sulphuric acid among all chemicals in magnitude of output (1,390,628 short tons in the United States in 1918) and fundamental importance, . . . . this (combination of the Haber and the Solvay processes) may well prove to be the most

11 See for example the articles by G. H. Fischer and Grinnell Jones already significant development in industrial chemistry of the present decade.’’8 5. The Ostwald Process. A subsidiary process bridging the gap from the product (ammonia) of the processes of the Haber and Frank and Caro types, to the market requirements of nitric acid (nitrate and nitrites), is the Ostwald process for the catalytic oxidation of ammonia. The Meteoric Rise of Nitrogen Fixation Industries. In the period during and immediately following the World War the situation in the nitrogen industries was abnormal, production being temporarily activated to fever heat, inasmuch as nitrogen compounds are among the most indispensable of war materials. Thus it came about that the development of nitrogen fixation had for its immediate motive not so much the constructive spirit of the arts of peace, providing for the future needs of men, as the malice and forethought of the conspirators of war. The conflict left on our hands, upon the conclusion of the armistice, both completed and unfinished manufacturing plants in excess of immediate needs in times of peace. Legislative difficulties also hampered well-designed efforts to convert these plants to industrial use. These are temporary conditions; although one may not be able to foresee exactly how, in detail, these industries will finally adjust themselves, there can be little doubt that from now on synthetic nitrogen compounds will continue to be drawn in increasing amounts from the atmosphere into the life cycle. The phenomenal growth of this infant industry within the past ten or twelve years is forcibly brought out in the graph (fig. 51) and the corresponding table 25. It will be observed that in 1909 only about 1 per cent of the world’s needs in combined nitrogen were satisfied from the new-born industry. In 1917 its contribution had swollen to 30 per cent, and by 1920 the capacity of existing plants was adequate to furnish 43 per cent of the world’s requirements.

This extraordinary development is something much more than a fundamental new departure in industry. It represents nothing less than the ushering in of a new ethnological era in the history of the human race, a new cosmic epoch. In the short span of a dozen years—geologically speaking in an instant—man has initiated transformations literally comparable in magnitude with cosmic 9]SUIS B UT yNdyNo eM WUNUIXBUT oY} st AIZSNpUT oyeVIYIU BTIYO oY} Jo Aytoedvo uMuUTIx¥UT yUeseIdor 07 oIBy poyrasuT aInSy tA

‘SUOTPIUN JO AIQSIUTP, YSIGIE OY} JO 904g;1UIUIOD S}onporg UaFOIJIN oY} Jo y10doy [eur oy} 07 yuosuTatddng jeornsyeig Wo, HS waTs sighetn Hass (eruourure 4099 Jed ¢'7Z pewnsse ozvyd -[ns) Aijsnput yonpoid-Ag xfisgsnpur uoynry uaboipu ay} fo asrs a140ajau a4; Burnoys ‘sjanposd uabospu ur saodinosas S.p]LOM processes. Accepting Arrhenius’ liberal estimate of the total quantity of combined nitrogen washed down to the soil in the annual rain fall over all continents of the globe, namely 400 million tons, it is seen that the new industry even now is capable of furnishing a supplementary supply equal to one six-hundredth of this prodigious quantity.

Economic and Energetic Significance of Concentration. We are, of course, greatly more interested in this six-hundredth which is under our control—and of which a due proportion falls, in consequence, upon our fields in concentrated form—than in the very much larger quantity that nature scatters with sublime indifference on stony places and good soil alike. This is just one of those cases to which reference has already been made in a general way. It is not so much the quantity of the material provided by nature that counts, as its accessibility ; and accessibility here means, among other things, suitable concentration. This question did not so obviously project itself into the discussion of the carbon cycle, because the natural source of carbon is atmospheric carbon dioxide, which, being a gas, in the very nature of things spreads evenly, and presents itself unsought, by a spontaneous process, at the mouth of the hungry plant. But the combined forms of nitrogen are for the most part solids or solutions, occurring in definitely localized amounts of greatly varying concentration. The labors forced upon us in our efforts to satisfy the nitrogen needs of our fields are, to be precise, not primarily work of production, but virtually work of concentration; or to be more exact, work of bringing about concentration at the particular locality where it is wanted—by transportation if need be. It is only because we find it easier, in some instances, to produce than to concentrate existing supplies, that we elect the former expedient; just as we may prefer to feed a boiler with a fresh supply of water, rather than to

14 For land and sea together Arrhenius estimates 1500 million tons of nitrogen in the rain fall. Since the writing of this chapter there have become available Trade Information Bulletins No. 226 and 240 of the U. 8. Department of Commerce, which give further and more recent data. In Bulletin 240 J. M. Braham estimates the capacity of the world’s nitrogen fixation plants at 496,000 tons for 1923. The reader interested in this topic may also consult J. R. Partington, The Nitrogen Industry, published by Constable, 1924.

return to it the condensed exhaust from the engine. That the mere concentration of existing supplies should at all require the doing of physical work is a circumstance of particular interest, not only in its economic relations,!® but also, and quite particularly, from the standpoint of energetics. This is a matter that will duly engage our attention in a later section, devoted to the energetics of the several processes that have here been considered in their purely material or stoichiometric aspect.

Meanwhile it is interesting to observe that such localized sources of concentrated supplies as those presented in the Chilean nitre beds virtually function as centers of attraction toward which gravitates a stream of human beings—or their representatives in the form of ships and other conveyances—arriving in search of cargo and going out laden with material. To an ultramundane observer who should survey the scene in suitable perspective, the activities around the nitre beds must appear very like the busy swarming of a colony of ants around the treasure trove of some silvan inhabitant departed this life; who, having completed his earthly career, is now yielding up, in the dissolution of death, such energies as still remain locked up in the carcass. Attractions such as this are, in a sense, merely apparent; they are the outward symptoms of a complicated chain of cause and effect!* characteristic of the behavior of living organisms. Yet they are often so consistent in their action that it would not be unreasonable to essay a systematic treatment of the movements in a world comprising such centers of attraction and such moving pawns, on the basis of brute tropisms unanalyzed into their ultimate component agencies. Here it must suffice to have pointed out that our highly complex industrial system, our far-flung intricate network of lines of traffic by land and sea, is but a sublimated copy, on a heroic scale, of the hustle and bustle that is going on all around us in nature, in response to attractions, tropisms, determinants of the

* A striking illustration of this is cited by Haber (Zeitschr. f. Angew, Chemie, 1910, I, p. 685). If the gold in sea water were extracted and apportioned evenly to all the human inhabitants of the globe, we should all be millionaires three times over; yet it does not pay to as much as begin this extraction. 16 Commonly accompanied by that anticipatory inversion of the sequence, in time, of effect and cause, which is the earmark of purposive action.

moves of an army of checkers over the mosaic of the earth’s topography.!7 Total Circulation Tends to Increase. The study of the nitrogen cycle furnishes us with a first occasion to take note of a phenomenon the full significance of which will become apparent in dealing with the dynamics of evolving systems. It is to be observed that the general trend of man’s effort, especially in this new epoch of nitrogen fixation, has been towards drawing into the organic circulation a greater amount of matter, enlarging the wheel of the mill of life, so to speak. There can be little doubt that this trend will continue and increase in the future, and that it is the expression of one aspect of a general law;!* the other aspect of this law, and its full significance, must be reserved for later discussion, as already intimated.

17 For a discussion of the natural concentrating processes the reader may be referred to the following articles: A. C. Lane, Nature’s Concentrators, Engineering and Mining Journal, 1897, vol. 63, p. 542. J. C. Russell, Concentration as a Geological Principle, Bulletin Geol. Soc. An., 1907, vol. 18, pp. 1-28. E. Blackwelder, The Geologic Réle of Phosphorus, Am. Jour. Sci., 1916, vol. 62, p. 285. W. Lindgren, Concentration and Circulation of the Elements from the Standpoint of Economic Geology, Economic Geology, 1923, vol. 18, pp. 419-442.

18 The phenomenon is, of course, closely related to that to which R. Lascaux refers as ‘‘une propriété particuliére de la vie: celle de Vextension’’ (La Production et la Population 1921, p. 37). See also A. J. Lotka, Proc. Nat’l Acad. Sci., 1922, p. 47. There is no coming into being of aught that perishes, nor any end for it — but only mingling, and separation of what has been mingled.— Empedocles. Immobile Elements. The circulation of water, carbon dioxide and oxygen in nature is greatly assisted by the freely occurring processes of evaporation, condensation (rainfall) and diffusion. In the case of nitrogen these processes still give some aid, as in the distribution broadcast of atmospheric nitrogen, and in the formation and precipitation of nitrogen “fixed’’ by lightning, etc. In phosphorus we have, on the contrary, a typical example of the inherently immobile elements needful to the living organism—to adopt Liebig’s phrase (ftir sich nicht beweglich). The successive steps in the concentration, diffusion, and reconcentration of this element, as available for the substance of the organism, accordingly display a characteristic complexity. Some of the principal items and steps in the phosphorus cycle are set forth in diagrammatic form in figure 52.

Natural Phosphorus Supply of Soils. The virgin soil contains, in general, a certain natural supply of phosphates. So, for example, Van Hise! reports that the virgin soil of Ohio, Illinois and Wisconsin contained, to a depth of 8 inches, 2077 pounds of P:O; per acre. After fifty-five years of cultivation this figure had sunk to 1813 pounds per acre, a loss of 36 per cent. These figures show the extreme importance of a conservation of our resources of phosphorus. The loss probably occurs partly through erosion by rain water charged with carbonic acid, which dissolves phosphates in the soil and in rocks, and ultimately washes a certain proportion out to sea. To this unavoidable loss, however, is added a large item of preventable loss through our failure to ensure that the phosphorus of animal wastes be returned to the soil. So, for example, farmyard manure contains over three-fourths of the phosphorus in the feed and bedding supplied to the animals. It is therefore very essential that this be returned

aIOALT) SQUOHdSOHG GH, “HUOLVNE NI SLNGAWATY HL AO NOILVTOOUID “Gg “DIY to the soil as completely as possible. Of the one-fourth of the phosphorus fed to the animals, and not accounted for in the manure, a considerable fraction appears in the bodies of these animals, especially in the bones. These, then, also should find their way back to the soil, as they do to some extent through the practice of using bone meal, either as such, or after conversion into superphosphate,? as fertilizer. This practice is materially assisted by the modern methods of meat production on a large scale, with very complete utilization of by-products.

Leakage of Phosphorus from Circulation. The human cadaver is in the great majority of cases returned to the soil in the regular course of events, although under conditions which, obviously do not render it very readily available for crop production. An adult contains about 14 pounds of phosphorus, or 3.4 pounds P2Os. If we allow one-half of this for a ‘‘unit of population,” 1.e., 1.7 pounds P,O;, with a death rate of 1.3 per cent per annum, we find that the amount of P,O; annually committed to the cemeteries of the United States is about 1105 tons. This is about the equivalent of 3300 tons of phosphate rock, or about one-thousandth of the annual production of that material in the United States.

But a very much larger amount of waste is occasioned from the human population by the practice of running the sewage from cities into rivers and thus to sea. Wan Hise estimates that annually 400,000 tons P:O; or the equivalent of 1,200,000 tons of phosphate rock are thus run to waste. He remarks: ‘‘The wide dispersal of the vast quantities of phosphorus which it took the process of nature an indefinite period to segregate, must cease. The loss is irreparable.’’ Much has been done in recent years to comply with this demand.

Phosphate Rock and the Migration of Phosphorus. In the meantime, in our phosphorus economy also, as in the case of the combined nitrogen of the Chilean nitre beds, we are living on our capital. For, as our fields tend to become depleted of phosphorus under intensive agriculture, we restore some of the rarefied element to the tired soil by drawing upon the accumulations of ages, in the form of phosphate rock. Asa matter of fact, in this we are welding

* By treatment with sulphuric acid, which renders the phosphorus more readily available to plants. These are technical details that cannot be entered into here. The reader must be referred to the pertinent agricultural and technological literature. the closing link in a very remarkable endless chain of nature. For the phosphates washed by the rivers’ into the sea serve as food to the marine vegetation and indirectly to the fishes and other aquatic species. These act in this case as concentrating agents, the bones and teeth of fish, and some shells of crustacea and molluscs, being comparatively rich in phosphorus.’ In its further migration the

5 For details the reader may be referred to an article by E. Blackwelder in the Am. Jour. Sci., 1916, vol. 62, p. 285, from which the following particularly pertinent passage may here be noted: ‘“‘Of the vast quantity of dissolved mineral matter annually delivered to the sea by the run-off, it is estimated that about 0.45 per cent consists of phosphorus pentoxide. Using the best available figures for the amount of water thus brought to the ocean annually, it is calculated that if the phosphatic material in the form of solid tri-calcium phosphate were loaded into standard railroad cars it would fill a train stretching continuously from Boston to Seattle and would be 7 to 12 times as great as the world’s total production of phosphate rock in 1911. Nevertheless, so great is the volume of the oceans, and so vast the area of their floors, that if all this material were deposited in solid form uniformly over the bottom of the sea, it would build annually a layer less than 0.2 mm. thick. Of the phosphorus poured into the sea, so large a proportion is utilized by living beings that the net working balance dissolved in oceanic water constantly averages less than 0.005 per cent, expressed as P2O;, or, in other words about 0.18 per cent of the dissolved salts. In this solution, phosphorus seems to have reached the most dilute state in which it exists during the course of its complex migrations. Its subsequent transformations generally tend to ever greater concentration, almost until the cycle is closed upon itself.

4 Compare also W. Lindgren, Concentration and Circulation of the Elements from the Standpoint of Economic Geology: ‘‘In the sea water the bluegreen algae concentrate phosphorus, certain mollusks or crustaceans feed on the algae, and other meat-eating mollusks devour the vegetarians. Small fishes eat the mollusks, large fishes eat the small, finally seals and birds swallow the fishes, and so in about six transformations the phosphorus originally contained in the sea-water may come to rest in deposits of guano on desert islands or in accumulations of bones of vertebrate denizens of the sea’’ (Economic Geology, 1923, vol. 18, p. 431).

5 In this connection may be noted again a passage trom Blackwelder’s article, p. 289 (see footnote 3): ‘‘As phosphorus ascends in the evolutionary scale of animals, its concentration tends to increase, although irregularly. The protozoan, air dried, contains less than 0.6 per cent P20s5. According to Juday quantities of minute crustaceans from Lake Mendota contain in the air-dried condition 1.8 to 2.4 per cent of P2Os, or several times that of the protozoans. A Russian biochemist, Sempelovski, found in entire fresh specimens of a cartilaginous fish (the common skate) 0.91 per cent P20s, whereas the average for eight Teleostean fishes with well-developed bones was about 1.5 per cent. Certain brachiopods, such as those of the family Lingulidae—form shells of fibro-crystalline tricalcium phosphate—probably either the mineral dahllite or staffelite.”’