TABLE II.-Hard-drawn Aluminium. Length of bar Temperature rise, Increase in length В= ΔΙ. 1(t2- t1) 2.413 X 10-5 2'406 in cm. =1. in mm. Al. 2.406 2'456 2'428 2'454 19 2'44I 99 2'436 2.431 2.438 The temperature rise of these parts was only small, and, owing to the shortness of the ends, the error caused was not greater than o'003 mm. The results obtained are somewhat higher than the recorded values of B. Fizeau (Comptes Rendus, 1869, lxviii., 1125; Fogg. Ann., 1869, CXxxviii., 28) found 2.313 X 10-5 up to 40° C. and 2336 × 10-5 up to 50° C., while Le Chatelier (Comptes Rendus, 1889, cviii., 1096), working with much purer aluminium, found 2:46 x 10-5 up to 63° C. The coefficient of linear expansion was invariably found to be slightly higher for annealed aluminium than for harddrawn aluminium, but the third significant figure is somewhat uncertain, owing to the errors of the determination. The mean value for 8, calculated from forty-eight determinations made upon hard and annealed aluminium, wasB = 2-450 X 10-5 per degree centigrade, or 1.361 x 10-5 per degree Fahrenheit. The above measurements were made upon twelve different rods, and the results were reproduced several times before they were considered reliable. The accuracy of the expansion apparatus was tested by measuring the expansion of a bar of pure high-conductivity 2.469 X 10-5 copper. The value obtained was 1758 x 10-5, a value 2'459 39 which is practically identical with that given by Zakrzewski (Krak. Anz., 1889, No. 19), who found 1.753 x 10-5. The general mean of the determinations given in origin in the lack of knowledge of the chemical composition Table III., sixteen in number, is— of the oganic matter of the soil. Some organic matter is essential to make a soil of what would otherwise be pulverised and more or less hydrolysed rock, and while there are some soils capable of growing crops that contain very small quantities of organic matter, on the whole the quantity of this material in average soils is considerable. Analyses have shown that the average organic content of the soils of the United States is 2.06 per cent and of subsoils 0.83 per cent (Cameron, Journ. Am. Chem. Soc., 1905, xxvii., 256). This means 28 tons of organic matter per acre in the first 8 inches of soil and 50 tons in the soil and subsoil together to the depth of 2 feet. The varied sources of this organic matter and the different classes of compounds that are known to result from the decomposition of this material have been fully discussed in a previous publication (Bull. 53, Bureau of Soils, U.S. Dept. Agr., 1909, p. 9), and it is necessary to state here simply the fact that this organic matter may have its * Bulletin No. 74, U.S. Department of Agriculture, Bureau of Soils, source in the remains of any plant or animal, and the | such knowledge is necessary because it carries with it a resulting compounds may be those that were in the living tissues and have resisted decay, those that result from a splitting or degradation of complex bodies present in the living plant or animal, or compounds arising through changes brought about by micro-organisms, and that nearly all classes of organic chemical compounds known may be represented. Two views regarding the soil organic matter are at present current in agricultural literature. The first is some modification of the view of Mulder (1849) ("The Chemistry of Vegetable and Animal Physiology,” trans. by Fromberg, 1849, p. 146), "that at present seven different organic substances are known to exist in the soil. They are crenic acid, apocrenic acid, geic acid, humic acid and humin, ulmic acid and ulmin." This view, modified to the extent that some such body as humic acid, differing perhaps in different soils, but having the same general properties, makes up the humus and the greater portion of the organic matter of all soils is accepted by many agronomists and chemists. The acceptance of this view. which originated in the days when there was no organic chemistry in the present meaning of the term, can be attributed to two factors which have tended to retard the progress not only of agricultural chemistry but of other branches of science as well. These are the tendency to simplify or unify what proper thought would show to be complex; and second, the too prevalent habit of some investigators and most compilers of repeating or quoting scientific statements or deductions which have been made in the first place on wholly insufficient grounds. This view of soil organic matter has been fully discussed in a previous bulletin (Bull. 53, Bureau of Soils, U.S. Dept. Agr., 1909, p. 21), and it is not necessary to repeat that discussion here, for one of the results of the present paper is to show that the bodies that Mulder regarded as simple compounds related to each other are really made up of a large number of chemical compounds not necessarily related. In strong contrast to this view of the simple composition of the soil organic matter is the second view current in agricultural literature, that the material is of a very complex nature, regarding which very little is known. Little fault can be found with this statement in itself, but it is often made in such a way as to convey the impression that not only do we know little regarding its complexity, but that it is almost hopeless to attempt any investigation of it. There is, moreover, seldom coupled with this confession of ignorance any appreciation of the importance of a thorough knowledge of the chemical composition of this important soil constituent. In considering the importance of the organic matter of the soil it should be borne in mind that it is material that is the result of change, and that much, perhaps all of it, is susceptible of still further change; that is, it is in a transition stage. The changes which it has undergone and the changes which it may still undergo are determined by a number of factors, chief of which are moisture, aeration, character of micro-organisms, and mutual relation of the organic compounds and the mineral constituents. These factors are many of them influenced or controlled by the cultural methods, including fertilising, drainage, irrigation, inoculation, &c., used in practical agriculture. While it is true that the soil, viewed from whatever point, presents dynamic problems, the study of the organic matter without doubt presents such problems in greatest complexity, but at the same time problems most susceptible of solution, once the character of the material is known. This view of the importance of soil organic matter concerns the agronomist and the farmer, but when the work of the special investigator is considered the need of definite knowledge is even more strongly emphasised. It is not necessary that the practical agriculturalist should know the chemical names or formulæ of the organic compounds in the soil, but to the scientific investigator, to whom the farmer looks for the "why" of agricultural operations, knowledge of their properties. There can be intelligent chemical treatment of any material only when the chemical nature of the material treated is known. The treatment to which soil organic matter is subjected under cultural methods is in part at least chemical treatment in that such methods induce chemical changes. The operations of irrigation, conserving of moisture by mulches, aeration by cultivation, inoculation with cultures of bacteria, addition of organic and green manures, are all common agricultural methods used by farmers, and they are also operations that influence the chemical changes which soil organic matter undergoes. The influence of the organic matter of the soil may be considered under four heads: Its effect on the crop, its effect on the bacteria and fungi of the soil, its influence on the physical properties of the soil, and its relation chemically to the mineral ingredients of the soil. It is a well-established fact that some chemical compounds which occur in plants and may get into the soil are harmful to growing plants when presented in water solution to the roots (Bull. 47, Bureau of Soils, U.S. Dept. Agr., 1907). It has also been shown that some organic compounds that occur in soils and have been isolated from them are also harmful to growing plants under these conditions (Bull. 53, Bureau of Soils, U.S. Dept. Agr., 1909). On the other hand, plants may take up other organic compounds when presented to their roots in water solution without injury to the plant, or in the case of some nitrogenous bodies, with benefit. Now, while the organic matter of soils is for the most part little soluble in water, a water extract of soils always contains some organic matter. In consequence organic compounds have always to be considered as a portion of the material in the nutrient solution supplied to crops growing in the soil. The chief function of bacteria and fungi is to act on the higher organic compounds which make up living organisms and convert them into simpler compounds. In other words, these higher compounds are the food of the microorganisms. The simpler compounds resulting from the activity of the fungi and bacteria commonly spoken of as the products of decay or fermentation, are, in part at least, still organic substances and help to make up this portion of the soil. No fact regarding bacteria is better established than that they are influenced not only in habit of growth but also in the character of the compounds produced, by the chemical composition of the medium in which they are grown and are generally intolerant of the presence of an excess of their own by-products. The soil organic matter impregnated with the soil solution is then the culture medium in which soil micro-organisms have to grow and contains also the products of their growth. Bacteria, the activity of which is beneficial to crops, may fail to flourish because the food supplied them is not suitable or because their own products or the products of other forms hinder their growth. On the other hand, the activity of harmful bacteria, fungi, or protozoa may be stimulated by an abundant supply of suitable food. The necessity, then, of some chemical knowledge of this culture medium and byproducts in any study of the mutual relation of soil microorganisms to each other or to crops is apparent. The properties of soils generally included under the term " physical," such as water-holding power, heat conductivity, absorption, and granulation, are universally recognised as potent factors in determining the character of a soil and its adaptability to the growing of crops. In considering these factors the tendency has been to consider the soil simply as an aggregate of mineral particles of different sizes, and consequently of different surface area, and to correlate the varying physical properties with this variation. That this view is wholly inadequate is evident, for solid organic matter may also be present in particles of different sizes, and these may have different physical properties due not only to variation in size, but probably in even greater degree to differences in chemical composition and structure. Furthermore, the organic } Chemical Nature of Soil Organic Matter. CHEMICAL NEWS Jan. 5, 1912 matter may, and in fact generally does, play an intimate part in the behaviour of the mineral particles, entering into chemical combination, coating them or cementing them together. The organic matter becomes, therefore, of the greatest importance in its influence on the great controlling factors in crop production, such as the solubility of the soil minerals, the physical structure of the soil granules, and the water-holding power of soils. To illustrate this, there was found in California a soil which could not be properly wetted, either by rain, irrigation, or movement of water from the subsoil, with the result that the land could not be used profitably for agriculture. On investigation it was found that this peculiarity of the soil was due to the organic matter, which when extracted had the properties of a varnish, repelling water to an extreme degree. The soil, once freed of this ingredient, had a high water-holding power. From other soils bodies of a waxy nature have been isolated. and it can thus be seen that certain kinds of organic matter are important as the cause of the low water-holding power of some soils, although in general the presence of the organic remains of plants increases the power of soils to hold moisture-an important factor in crop production. It is evident, then, that there can be intelligent study of the influence that the organic matter of the soil has on its physical properties only when the chemical identity of its several components is known. The great majority of organic chemical compounds are reactive towards inorganic compounds, acids, bases, and salts. Organic acids can form salts with mineral bases or double salts with mineral salts. Organic bases form salts with mineral acids, and quite a number of organic compounds combine both acid and basic properties and form organic compounds with both mineral acids and bases. Such being the case, there necessarily exists a mutual relation between the organic compounds in the soil and the mineral particles which form its foundation. Some of the acids isolated from the soils could not exist free for any time in a soil containing free bases or salts of weak acids, such as carbonic acid, and there is abundant evidence that many of the organic compounds exist in the soil in mineral combination. In fact, the relation between the organic and mineral particles of the soil is so intimate that any differentiation of soil chemistry into organic and inorganic should not be used as the basis of any theory or line of argu.nent regarding soil phenomena or soil treat ment. In Bulletin 53 of this bureau the methods of isolating four organic compounds from soils was described and their properties given. The isolated compounds were :Dihydroxystearic acid, C18H3604 picoline carboxylic acid, CHO2N; agroceric acid, C21H42O3; and agrosterol, C26H44O.H2O. Since the publication in this Bulletin of a review of the literature bearing on the nature of the organic matter of the soils, there have appeared several papers on the methods of humus determination and on the nature of the nitrogenous compounds resulting from the decomposition of the humus material with acids. None, however, have added any definite information regarding the identity of any compounds in the organic portion of the soil. A paper by Miklauz is a valuable contribution to our knowof the variable character of humus material ("Beiträge zur Kentniss der Humussubstanzen," Zeit. f. Moorkultur und Toriverwertung, 1908, 285). This paper deals for the most part with the solubility of humus bodies in different solvents and the differences in the elementary composition of the separate fractions obtained by this means. With the idea of the general importance of a greater knowledge of the chemistry of the soil organic matter in mind, and with the view of furnishing more specific information of value in attempting to solve some of the problems presented by differences in or lack of fertility of soils, the work of which the present paper is a report was undertaken. 7 The work deals with a number of soils selected because of some problem presented by field observation, although these problems are not dealt with here. No one soil has been studied exhaustively, nor has there been any attempt to account for all of the organic matter in the soil in identified compounds. In some cases, however, this is approached by the sum of the identified compounds and separated fractions, the composition and properties of which are known but the identity of which has not as yet been established. Two general methods have been used in the preliminary treatment of soils to obtain a solution from which to isolate organic compounds. These were the treatment with dilute alkali as in previous work and treatment with boiling 95 per cent alcohol. In several cases the same compounds were obtained by both methods. It is quite evident that the compounds isolated from soils and described in this Bulletin could not have been formed by any deep-seated change effected by the alkali or alcohol in the method of extraction. The alkali used was dilute, 2 per cent, the treatment was at room temperature and for a short time only, and the compounds isolated are not known to be formed by decomposition of more complex organic material by any such treatment. This treatment does effect changes in some of the organic matter of soils, but the material changed and the resulting compounds are not dealt with in this publication. The after treatment of these solutions was also along two general lines. First, general treatments used in the separation or isolation of organic compounds, for the most part shaking out with immiscible solvents and precipitating with metallic salts, and, second, the direct search for certain compounds by methods already used for the isolation of such bodies in biochemical work. When definite compounds were obtained by the general search, where the method used gave little or no clue to the identity of the compound obtained, it was necessary to obtain sufficient of the body to determine its elementary composition and its general properties in order to establish its identity. When, however, a compound was obtained as the result of a direct search by an approved method, the correspondence of the properties, such as melting-point, crystalline appearance, solubility, &c., of the compound obtained and the compound sought has been deemed sufficient to establish its identity. The compounds obtained have been classified and described according to the group of chemical compounds to two or more groups have been obtained as steps in one to which they belong. In some cases compounds belonging method, and if treated wholly from the point of view of method these would be described together. Since, however, the number of bodies isolated is constantly increasing, the classification according to method would soon result in confusion, and the chemical classification has been adhered to even when there was but one representative of a group. When compounds isolated have been obtained at different stages in the same method of treatment the fact is made clear in the text. (To be continued) Behaviour of Metallic Hydrates towards Alkylenediamine Solutions.-Wilhelm Traube.-Copper hy. droxide is less soluble in aqueous solutions of primary aliphatic amines than in ammonia, but I . 2-diamines containing two primary amino-groups are excellent solvents for it. One molecular weight of copper is always dissolved for every two molecular weights of diamine in the solution. Probably a cupric-ethylene-diamine hydroxide of formula [Cu(C2H8N2)2 (OH)2 is present in the solution, but the author has not succeeded in isolating it. hydrates of nickel, cobalt, zinc, and cadmium, and the oxides of silver and mercury are also taken up by alkylene diamines in definite molecular proportions.-Berichte, xliv., No. 16. The 318. "The Porosity of Iron and its Relation to Passivity and Corrosion." By JOHN ALBERT NEWTON Friend. The author showed that:-(1) The surface of iron is slightly porous, so that when the metal is immersed in certain solutions the latter are absorbed to a minute extent. (2) The passivity induced by immersion of iron in alkaline solutions, such as those of sodium and potassium hydroxides, is due to absorption of small quantities of these alkalis within the pores of the metal. (3) There are thus more kinds of passivity than one. 319. "Molecular Rotatory Power in Normal Homologous Series. Part I. Optically Active Derivatives of the Higher Aliphatic Alcohols and Acids." BY THOMAS PERCY HILDITCH. The variation of different types of physical properties in consecutive members of an homologous series was discussed, and it was pointed out that, whilst the more additive properties increase in arithmetical progression on ascending such a series, certain essentially constitutive properties tend in these circumstances to arrive at a constant value. A survey of the existing data on the molecular rotatory powers of optically active homologues shows that here also, although hitherto only the first few members of series of this type have been available, this function nevertheless reaches in many cases an approximately constant figure, characteristic of the optically active series concerned ; moreover, those series which do not yield constant values for [M] D almost invariably contain strongly unsaturated groups. The author therefore proposes to investigate the homologues of higher molecular weight of some apparently irregular series in order to determine whether the presence of unsaturation is here a disturbing factor in the lower members. To this end it was necessary in the first place attained constancy of molecular rotatory power, the homoto ensure that, in series the lower members of which rapidly logues of high molecular weight should maintain their series constant" of molecular rotation. 5-Dimethylaminoanilo-3 4-diphenylcyclopentene-1 : 2dione when treated with bromine gives a yellow bromoderivative, C25H1902N2Br, but with an excess of the halogen an unstable perbromide is produced, which on monobromo-derivative along with a scarlet dibromo-comboiling with alcohol decomposes to yield the same yellow" pound, C25H1802N2Br2. With fuming nitric acid the substance forms a scarlet dinitro-derivative, C25H18O2N2(NO2)2; on reduction with zinc dust and acetic acid it furnishes a colourless compound, C25H22O2N2. 5-Dimethylaminoanilo-3: 4-diphenylcyclopentene - I : 2dione is deep red or orange, according to whether it sepa: rates from concentrated or dilute alcoholic solutions. It 2R.CH:X+2H = R.CH(XH)·CH(XH)·R. Thus benzylidene-p-toluidine yielded benzyl p-toluidine, di-p-toluidinodibenzyl, and a green resin. The relative quantity of each constituent varied with the conditions of the experiment, but followed the same rules as those previously given in the case of benzaldehyde. The quantities of each substance formed varied very considerably with a change in constitution. The resin formed diminished as the formula of the reduced substance approached the most symmetrical arrangement of the substituted groups. cinchonine salts of myristic, palmitic, and stearic acids, Investigation of the menthyl esters, and brucine and and of the hydrogen camphorates and camphor-8-sulphonates of cetyl and myricyl alcohols, showed that, within narrow limits, the molecular rotatory powers of the normal aliphatic esters of l-menthol, d-camphoric acid, and d-camphor-8-sulphonic acid, and of the normal ally constant in each series after the first few members are aliphatic salts of brucine and cinchonine, become numeric passed. 320. "Molecular Rotatory Power in Normal Homologous Series. Part II. The Menthyl Esters of the a-Bromoaliphatic Acids." By HAROLD CHRISTOPHER and THOMAS PERCY HILDItch. The effect of introducing an unsaturated group in close proximity to the carboxyl residue of a series of optically active normal aliphatic esters has been studied by the effect of unsaturation referred to in the preceding paper. authors in connection with the problem of the disturbing I-menthol were employed in the present investigation on The a-bromo-derivatives of the aliphatic esters of account of the ease with which these compounds may be obtained in the pure condition. It was found that whilst the first two members of the series (menthyl bromoacetate and a-bromopropionate) possessed molecular rotatory powers markedly above the normal, the anomaly rapidly declined to a minimum, slightly sub-normal value, thereafter rising very much more gradually to an approximately constant value (in the case of menthyl a-bromomyristate and a-bromopalmitate). The final constant molecular rotations appeared to be a very few degrees in excess of those of the corresponding members of the saturated non-substituted aliphatic menthyl esters. CHEMICAL NEWS, Jan. 5, 1912 } Experimental Investigation of the Bleaching Process. 9 321. "Note on Methyl-n-tridecyl- and Methyl-n-penta- | hydrogen phthalate separates from light petroleum as a decyl-carbinols and the corresponding Ketones." By ROBERT HOWSON PICKARD and JOSEPH KENYON. In a recent communication (Trans., 1911, xcix., 45) the authors have described the resolution into their optically active components of the members of the series of carbinols from methylethylcarbinol to methyl-n-undecylcarbinol. It was intended to continue the series so as to include methyln-tridecyl- and methyl-n-pentadecylcarbinols, but it has been found that the method of bringing about the resolution of the various members of the series fails in the case of these carbinols, containing fifteen and seventeen carbon atoms respectively. This note contains a short description of the compounds isolated during the course of the experiments, and also shows that the catalytic method with thorium oxide (Senderens, Comptes Rendus, 1909, cxlv., 995) can be used for the formation of ketones, even when they contain many carbon atoms. Methyl-n-tridecyl Ketone, CH, CO·C13H27.-Myristic acid (300 grms.) dissolved in glacial acetic acid (2400 grms.) was passed at an hourly rate of 50 cc. through a Jena-glass tube containing thorium oxide, and heated to 400°. The products of the reaction were condensed, dissolved in ether, and washed with a solution of sodium hydroxide until free from acid. Myristic acid (125 grms.) was recovered from the washings, mixed afresh with glacial acetic acid, and again treated. When the products from the two operations were fractionally distilled, 200 grms. of methyl-ntridecyl ketone were obtained. The residue in the flask when re-crystallised from ethyl alcohol yielded 30 grms. of myristone, which melted at 75—76°. Methyl-n-tridecyl ketone boils at 184°/20 mm., and on cooling sets to a soft mass of crystals, which melt at 37°. It readily forms the semicarbazone, which crystallises from ethyl alcohol in needles melting at 1265°. (Found, N=150. Calc., N = 14.8 per cent). Methyln tridecylcarbinol, CH3 CH(OH)·C13H27, is readily obtained when the corresponding ketone is reduced by sodium in 96 per cent alcoholic solution, little, if any, pinacone being formed. It boils at 181-1830/19 mm., and on cooling sets to a crystalline mass, which melts at 38-39°. The hydrogen phthalate crystallises from light petroleum in pearly leaflets, and melts at 61-62°. (The purity of each of the acid esters described in this note was ascer. tained by titration of their alcoholic solutions with a standard solution of sodium hydroxide). The brucine salt crystallises from acetone in needles, which, when dried in the air, melt at 80-85°, but after desiccation in a vacuum or after heating at 105° for a few minutes they melt at 172-175°. After two re-crystallisatious, on polarimetric examination :: 10136, made up to 20 cc., with ethyl alcohol, gave a -6.25°, whence [a] - 61.66°. The strychnine salt crystallises from chloroform and acetone in hair-like needles, melts about 130°, and has [a]D-52.6° when dissolved in chloroform. The hydrogen phthalate obtained from the purest specimen of these salts was in each case found to be quite inactive when examined in the polarimerer. The hydrogen succinate crystallises from light petroleum in nacreous leaflets, which melt at 60-61°. The brucine salt is a wax, and unsuitable for fractional crystallisation. The corresponding derivatives of heptadecane were obtained by similar methods. Seventy-nine grms. of methyl-n-pentadecyl ketone, mass of needles, which melt at 50-51°. The hydrogen succinate separates from light petroleum in a microcrystalline condition, and melts at 64-65°. The brucine salts of each of the esters were prepared and re-crystallised several times, but no ester could be obtained which exhibited any trace of optical activity. 322. "An Experimental Investigation of the Bleaching Process." By SYDNEY Herbert HIGGINS. Solutions of the hypochlorites of lithium, sodium, and potassium prepared from bleaching powder solution by precipitation with solutions of the alkali sulphates or carbonates have identical bleaching properties; the bleaching efficiencies of these solutions are almost equal to that of the original bleaching powder solution. Curves showing (1) the evolution of oxygen from hypochlorite solutions and from solutions of sodium peroxide in contact with copper oxide; (2) the rate of bleaching of solutions of hypochlorites and of sodium peroxide; (3) the rate of oxidation of oxalic acid by potassium permanganate and the rate of liberation of iodine from potassium iodide by acidified sodium peroxide solution (Harcourt and Esson, Phil. Trans., 1866, clvi., 193), point to the conclusion that the actions in all these cases are similar, that is, uniHypochlorites therefore bleach because of molecular. their readiness directly to produce nascent oxygen. Those substances which accelerate the evolution of oxygen from solutions of hypochlorites or of peroxides also assist the evolution of that gas when they are heated along with potassium chlorate; hence it is taken that the main action in the latter case is a unimolecular one. Chlorine water is a much weaker bleaching agent than solutions of hypochlorites; therefore the bleaching action of the latter cannot be due to the generation of free chlorine as stated by Taylor (Trans., 1910, xcvii., 2541). Chlorine water probably owes its bleaching properties to the presence of hypochlorous acid in solution. The proof that the production of chlorine from bleaching powder solution and the stimulation of the bleaching action of that solution have no connection with one another has led the author to consider the two questions separately. In pursuit of this line of argument he gave further experiments supporting previous conclusions (compare Taylor, Proc. Chem. Soc., xxvii., 243). 323. "The Direct Esterification of Saturated and Unsaturated Acids." By EBENEzer Rees ThoMAS and JOHN JOSEPH SUDBorough. The esterification of a number of saturated and unsaturated organic acids has been studied by heating the acid with a large excess of pure ethyl alcohol at 100° in sealed tubes for given periods, and titrating the amount of free acid left. The results show that an aß-olefine linking has a retarding effect, except when the unsaturated acid is a very much stronger acid than its saturated analogue, for example, methyl hydrogen maleate, which is some hundred times as strong an acid as methyl hydrogen succinate. In such a case the olefinic acid is esterified more rapidly than the corresponding saturated acid. two A By-unsaturated acid is usually esterified somewhat more rapidly than its saturated analogue, and a d-olefinic linking appears to have but little effect on the rate of esterification. |