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Contributions towards a Knowledge of the Inorganic Constituents of Plants, by Dr. Charles A. Cameron, M.R.I. A., F.C.S.L, Corresponding Member of the Agricultural Societies of New York, Belgium, fyc.
At a meeting of the Koyal Dublin Society, held on Monday evening, April 16, Professor Barker in the chair, the following paper was read:—
One of the most interesting problems in the chemistry of vegetal physiology is, "What are the inorganic constituents of plan ts?" Until this problem is satisfactorily solved there can be no true theory of agriculture, and the science of phytochemy must remain very defective in a most essential point.
The inorganic constituents of a plant are, as compared ■with the organic, very small in quantity j indeed, their apparent insignificance at one time led to the belief that they were unessential components of the vegetal mechanism. We now know—thanks to the intelligently directed labours of a host of investigators—that every plant, excepting a few of the very lowest organisation, must contain a certain amount of mineral matter, which varies both in nature and amount in different kinds of plants, and also, but to a far less extent, in different individuals of the same species. The limits of these variations it is the province of the chemist to discover, and until they are ascertained our knowledge of the nature of tho food of plants must remain in a very unsatisfactory state.
Early in the present century, De Saussure, Davy, and Dundonald pointed out the natural affinity which certain plants exhibited for particular earthy and saline substances. Davy showed that clover invariably contained a large proportion of sulphate of calcium, and that silica abounded in oats. Since Sir Humphry Davy's time, but more especially within the last twenty years, a great number of chemists have occupied themselves with researches, the object of which was to discover whether or not the chemical composition of the incombustible part of plants is a specific distinction. Other experimenters have, during the same time, endeavoured to prove the possibility of replacing the mineral bodies commonly and abundantly found in certain plants by others which are either rare constituents of those plants or which occur in them but in minute quantities. These researches have not been barren in useful results. On the contrary, we have derived from them a vase amount of information relative to the composition of the vegetal fabric, and to the relationship subsisting between the plant and the soil on which it grows; and tho application of the knowledge so obtained to agriculture and horticulture has improved to a great extent many of the processes of those ancient and important arts. But whilst fully admitting the practical utility of those investigations, it is certain that their results shed, after all, but a feeble light on that part of the domain of nature they were intended strongly to illuminate. Indeed, in numerous instances the experiments of different chemists, made with the same object in view, yielded the most discordant results; and until the subject has been more thoroughly investigated, and until the results of the researches of the various explorers prove more harmonious, the problem, " What are the essential, the useful, and the accidental inorganic constituents of plants P" must remain in a state of but partial solution.
Eleven elementary bodies occur so commonly in the ashes of plants that they are usually indicated in books on botany and agricultural chemistry as essential constituents of plants. These bodies are the following :— Potassium, sodium, calcium, magnesium, iron, silicon, phosphorus, sulphur, chlorine, bromine, and iodine. There are six others which occur—some of them frequently, the rest rarely—in plants, and the claim of each of which to be ranked as a normal constituent of at least certain species is supported by at least one chemist. These elements are the following :—Lithium, aluminium, manganese, copper, lead, and fluorine. My object in reading this paper belore the Society is to endeavour to prove by the results of my own investigations, as well as from those of others,* that the last named substances, and one at least of the others, are not essential constituents of plants. My experiments extended over a period of five years. They were conducted in the most careful manner, and every precaution against error that I could think of was scrupulously observed. I started not with the object of experimentally establishing a preconceived theory, but simply with the view of elucidating the truth. I trust, therefore, that the following statements may be considered worthy of being added to what tho late Professor Johnston termed "the multiplication of results in which confidence con be placed."
Experiments with Potassium. Potassium, in combination with oxygen and chlorine, appears to be a constant constituent of plants. It exists in great abundance in most species of the orders Umbelliferce, Composita;, Gramineea, Amentaceoc, and Chenopodiacese. Some members of these families evince so great a partiality for potash that it is often found to constitute one-half of the weight of their ashes. The fact of potassium being constantly present in every part of plants, favours the supposition that it is an indispensable constituent of the vegetal fabric. The statements of the analyses of the ashes of plants are scattered throughout the pages of so many books and journals, and published in so many languages, that it is all but impossible that every one of them should come under the notice of even the most industrious researcher. I have wandered through the pages of hundreds of books and periodicals in quest of statements of the analyses of the mineral part of plants, and in several thousands of them which I have perused I only noticed in one or two instances the absence of potassium. According to James, the ash of the Fucus vesiculosus yields 22-15 P** centum of soda and chloride of sodium, but is destitute of potassium. It is more than probable that in James's analysis the amount stated to be soda was made up of the two fixed alkalies, as it is well known that all the fugaccte contain a large proportion of potassium compounds. Godechens proved that it contained no less than 30 per centum of oxide and chloride of potassium. My examination of several specimens of the same plant, grown upon the coast of the County of Dublin, showed that potassium was one of its most abundant constituents. In fourteen analyses of different kinds of fucus made by Forchhammer, the alkalies were equal in amount. Indeed, the results of all the analyses of the sea-weeds mode by Claubry, Hodges, Johnston, and others, agree in setting down potassium as an invariable component of the ashes of those plants. In two analyses of the red beech, published by Baer, potassium does not appear;
* Chiefly those of Liebig, Daubeny, Way and Ogatou, RanimeUbeTtr Welgman, Folstorff, Magnus, VoelcVer, Bousgingault, tho Prino* of Balm-Hontmsr, Bischof, Hruschauor, Staffel, aud ErJuiouu.
According to Will, Fresenius, and Daubeny, wheat grown near the coast contains more potassium and less sodium than it does when cultivated in situations remote from the sea; but the results of the analyses of the ashes of wheat grown in different localities, made by "Way, point to an opposite conclusion.
In the analyses of fossil fuel (the altered remains of plants), the absence of potassium has been frequently noticed. Baer (who appears to have an instinct for ascertaining the absence of this element from plants and their remains) states that it does not occur in the ashes of two varieties of coal. He, however, detected it in the ashes of other kinds. But even admitting that potassium has never been found in the ashes of fossil plants, it would not prove that it was unessential to the living plant. Who can tell the precise nature of the changes which vegetal substances undergo in their transition from the condition of living tissue to that of fossil coal? During the process of its partial decomposition, may not the alkaline chlorides, if present, be separated by the agency of water? To show how little light the analysis of the mineral part of coal is likely to throw on the nature of the normal inorganic constituents of plants, I need only quote the curious results of Richardson's examination of the ashes of coal used at Kelso, in Scotland. In 100 parts there were the following substances:—
Sesquioxide of iron . . . .26-99
Silicic acid 1-84
Sulphuric acid 21 -20
Titanic acid 7-01
Chlorine 9 "57
My own investigations, the results of which I shall now proceed to state, lead me to conclude that potassium is essential to plants, but that it may be partly replaced by sodium. My experiments to determine this point were conducted in the following manner:—
I used twelve vessels made of block-tin, each twenty inches in height, and varying in area from sixteen inches to three feet square. These vessels were partly filled with artificial soil composed of the following substances:— Coarse quartzose sand . . . 25 parts Alumina . . . . . 15 „ Sulphate of barium . . . 60 „ The quartzose sand had been well washed with pure hydrochloric acid, and subsequently with distilled water. The alumina was thoroughly freed from every substance with which it is usually found associated. By repeating many times the process of dissolving it in hydrochloric acid, precipitating it by means of ammonia, and thoroughly washing the precipitate with warm distilled
water, the complete separation of potassium was rendered certain. The sulphate of barium was prepared by mixing a dilute solution of chloride of barium with sulphuric acid. The precipitate obtained was boiled in hydrochloric acid, and subsequently repeatedly washed with hot distilled water. Sulphate of barium is not absolutely insoluble in water, but it is so nearly so that I have grown plants in it repeatedly, and have never found them to take up the most minute trace of it.
This artificial soil I found to answer my purpose very well, and no other kind, except in one instance, was employed in any of the experiments described in this paper.
The twelve vessels were divided into three groups, a, b, and c; the vessels of each group were then numbered 1, 2, 3, and 4.
The vessels of group a were supplied respectively with a compound of the following substances:—
Chloride of sodium . . . .20
Bicarbonate of sodium .... 2
Nitrate of sodium %
Phosphate of sodium .... 2
The vessels of group 6 were supplied with a mixture similar to that placed in the vessels of group a, but with the addition of four parts of potash.
In the mixture supplied to the vessels of group c, nil the ingredients above stated were present, and in the same proportion, except the sodium compounds, which were replaced by equivalent quantities of potassium salts.
The quantity of artificial manure applied, was about 2 per centum of the weight of the soil; a larger proportion would probably have proved injurious.
In vessels No. 1 of the three groups, seeds of barley were sown; in vessels No. 2, seeds of oats j in vessels No. 3, seeds of peas; and in vessels No. 4, seeds of the gra3s Poa trivialis.
An average number of the seeds germinated and produced stems. During the development of the plants, the nitrogen required for their nutrition was supplied by the nitrate of sodium, and by watering them with an exceedingly dilute solution of carbonate of ammonium. Carbon was supplied by the bicarbonate of sodium, and by watering the plants with a solution of carbonic acid gas in water: gaseous carbonic acid gas was also supplied to them. The plants were placed in a good southern aspect, and were protected by large glass shades.
Jiesults;—The barley seeds sown in the soil destitute of potassium, germinated perfectly and produced plants. These were reduced to twelve in number, and their development progressed in the following manner:—By the twentieth day three of the plants had perished. Of the nine remaining, only two were healthy and had attained the height of ten inches. The others were sickly, and varied in height from six to nine inches. On the fortieth day only one plant was alive, and this presented nnmistakeable symptoms of approaching death. By the forty-second day every plant had perished.
The oat seed sown germinated, and produced stalks, but, as in the case of the barley, not one of them reached a perfect state of development, and no effort to produce seed, or even to flower was made.
The peas sown were the variety termed " Warwick Gray," which, under ordinary circumstances, are hardy, vigorous plants. In this case, the haulms were very slight, and of a pale colour; in no instance were there more than four small leaves developed; the greatest height attained was only twelve inches; and all the plants perished before the twenty-eighth day.
The Poa trivialit seeds produced plants which appeared to thrive better without potassium than any other of the plants experimented upon. Some of the culms perished very soon, but others survived for nearly two months, and in several instances made a feeble attempt at flowering; but in no case was the most minute seed developed.
The barley sown in vessel No. 1 of group 4, germinated and produced twenty-nine plants. These were reduced to twelve, of which six perished within thirty days, two more within forty, and the four others attained an average height of 23 inches, and produced small ears, with, on an average, eighteen little grains.
The oat seed sown in vessel No. z, group b, yielded almost precisely similar results to those above stated. The larger number of plants perished, and the survivors were stunted, and produced but a small quantity of grain.
The peas throve better than the cereal plants. Of six plants, one attained the height of 2 feet 1 inch; two were under 15 inches, and one under 12 inches, all these produced very small pods, containing in each three seeds. The two others perished without flowering.
The Poa trivialis grew up very luxuriantly, and produced seeds, which, however, were under tho normal 6ize, and not very numerous.
The barley, oats, peas, and grass to which the potassium (vessels 1, 2, 3, 4, group c) salts, but no sodium compounds, had been supplied, germinated perfectly and produced plants, which in due season performed the lost function of vegetation—the production of seed.
The plants grown in the vessels of group 5 were calcined, and their ashes submitted to analysis, the results of which are given in the following table:— Analysis of the Ashes of (tchole) Plants, grown in soils containing a small proportion of Potassium compounds.
in those plants they are stunted in development, flower with difficulty, and produce very inferior seed.
4th. That there is every reason to infer, from tho results of this investigation, that similar researches on other plants would give similar results.
Tho chief features of interest in this investigation, besides those alluded to above, are the following :—The remarkable instinct which guided the plants in seeking out and appropriating the minute quantity of potassium contained in the soil.f The grass, Poa trivialis, which, according to Way and Ogston, naturally contains no sodium, taking up so large n quantity of that element. The peas thriving better than the oats and barley, and in this respect being exceeded by the grass. The plants supplied with every substance considered essential to their nutrition, although attaining to a perfect development, being very inferior to those grown in the field. For this fact I am unable to assign a satisfactory reason. (To be continued.)
PHARMACY, TOXICOLOGY, &c.
On the Determination of the Presence of Sulphates of Cinchonine and Quinidine in Commercial Sulphate of Quinine, by M. KoGEB.
This process, which has been modified by various chemists, remains, nevertheless, essentially the same; all the modifications suggested have been ba*ed on one chemical fact,—to set the quinine of the sulphate at liberty, and to dissolve it in pure ether. Liebig's process is at present generally employed. It consists, as we know, in treating 1 gramme of sulphate of quinine put into a long bottle, or into a small, easily-stopped burette. To this is added 10 grammes of pure ether, then 2 grammes of caustic ammonia; the vessel is tightly closed and quickly shaken; and, if the sulphate of quinine is pure, a complete solution is instantaneously effected, and the limpid liquid will divide into two layers,—one etherised, containing all the quinine; the other aqueous, containing the sulphate of ammonia. If, on the contrary, the sulphate contains cinchonine or quinidine, a more or less abundant white flaky deposit will be observed at the junction of the two liquid?.
I have many times had occasion to use this process, and always with satisfactory results; but then I used ordinary pharmaceutical ether. In one instance, I by chance employed pure instead of ordinary ether, and failed to obtain the same reaction.
In this case the quinine was only partially dissolved in pure ether; some time after, the liquid solidified into a transparent opal jelly, resembling balsam of opodeldoc. After standing for twenty-four hours, the vessel was shaken briskly, and the jelly thrown on a filter became disintegrated; the ammomacal liquid and the ether saturated with quinine passed quickly, and a granular white substance remained on the filter, containing a large proportion of ether.
At first I thought this substance was cinchonine or quinidine, but then the quantity of it seemed too large for this supposition. After washing the residue several times with ether, then with distilled water, and finally drying it in a hot air stove, I examined it and found that with all the well known quinine reagents it behaved like qninine itself. Having thus positively proved this substance to be quinine, it remained forme to investigate the eause of this phenomenon.
t Leu than the one-thoueandtb. port of iu weight.
I started with the supposition that the quantity of quinine contained in a gramme of sulphate of quinine is, perhaps, too large to be dissolved in 10 grammes of pure ether, for we have hitherto been ignorant of the degree of solubility of quinine, under the different states in which it is found, but that it might well be soluble in ordinary ether, which usually contains more or less alcohol.
To solve this double problem, I increased the proportion of pure ether j instead of 10 grammes of ether to i gramme of sulphate of quinine, I used successively 15, 20, and 25 grammes, and found that only with the largest quantity could I completely dissolve the quinine. Then it occurred to me to try the effect of previously adding to the ether 1 per cent, of alcohol at 900; but with this addition tho ether gave an imperfect solution, and after a few hours the mixture gelatinised. With 14 per cent, of alcohol I obtained an almost complete solution, and the mixture remained liquid; and with a percent, the quinine was perfectly dissolved.
The result of these observations is that 10 grammes of pure ether are not sufficient to dissolve completely the quantity of quinine contained in 1 gramme of sulphate of quinine, and that 25 grammes are required to obtain a complete solution j this, then, is the degree of solubility of quinine, recently set at liberty, in pure ether.
That, on the contrary, this same quantity of quinine dissolves very well in ether, with the addition of 2 per cent, of alcohol at 90°, and that ordinary ether acts in the same way only because it always contains more or less considerable quantities of alcohol.
It is, of course, understood that these experiments and observations do not invalidate Liebig's process for recognising sulphates of cinchonine and quinidine—sometimes both together—in suspected sulphate of quinine; it is necessary only, instead of pure ether, to use it with the addition of 2 per cent, of alcohol at 90°. In fact, as we have many times proved, by mixing pure sulphate of quinine with pure sulphates of cinchonine and quinidine in the proportion of io-6 and 4 per cent, only, these substances remain insoluble, and may easily be estimated at the junction of the two etherised and aqueous liquids. It must, however, be remarked that a portion of the quinidine precipitates to the bottom of the tube.
•Finally, may I be allowed to say a few words on this magma—this jelly obtained by employing pure ether? Is it a hydrate of quinine incorporating almost all the ether employed and forcibly retaining it? To me it appears rather as a combination of ether and quinine resembling a hydrate or alooholate, and might, strictly speaking, be called an etherutc of quinine.
As to the sulphate of ammonia formed during this operation, I do not thiuk it is the cause of the formation of this magma.
M. Andre, who has devoted a short time to these researches, has isolated the quinine of the sulphate by means of ammonia, and after several washings entirely freed the quinine from sulphate of ammonia; nevertheless, when treated by pure ether in the proportions indicated above.|c he magma was still produced.—Journal de Pharmacie.
Recent Researches on Metallic Amalgams, and on the
Origin of their Chemical Properties, by M. J.
Keonauld. In a preceding work I have shown that the chemical properties of amalgamated zinc and cadmium are connected with the thermic phenomena which take place at the moment when these two bodies are united to mercury. My recent investigations tend to generalise these relations. These investigations extend over a considerable number of metals, and prove that, by the fact of amalgamation, some, such as zinc, rise in the scale of positive affinities, while, on the contrary, others, such as cadmium, are lowered.
Among the metals submitted to these comparative experiments, the following, when allied to mercury, become electro-positives: Iron, nickel, cobalt, zinc, tin, antimony, copper, lead, bismuth.
Among these bodies, only zinc, tin, and lead combine with mercury by simple contact and without auxiliary chemical or physical action. I havo ascertained that during the amalgamation of tin and lead, and likewise zinc, the temperature is not lowered. Thus then, in all three cases where the temperature can be observed during the reaction, it is found that the positive^ affinity of the compound augments when the heat of its constitution increases.
Hence, it may be concluded that other amalgamated metals, having identical properties, owe them to the same cause. Let me add that a comparison of their latent heat of fusion, and of the chemical rank they hold, is very favourable to this point of view. It is easy to be convinced of this by examining the table in which the latent heat of fusion of tho metals experimented upon arc shown. Some are exact, and are the result of calorimetric determinations; others have only approximate vapours, deduced from the relation established by M. Person, between latent heat, the co-efficient of elasticity, and the density of the metals.
Latent Heat of
Iron 64-171 Calculation.
Nickel . . . • 55-397 ..
Cobalt .... Sl633 •■
Zinc 28'130 Experiment.
Antimony. . . . 12 455 Calculation.
Load 5'3°9 Experiment.
Bismuth .... 12640 „
The affinity of the three first metals of the table with mercury differs very slightly from that of zinc; and as their latent heat is decidedly superior to that of zinc, the increase of positive affinity in the amalgams is duo to this circumstance.
The electro-chemical properties of the amalgamated metals placed below zinc are also explicable on the same principles. In fact, if on the one hand their latent heat is generally inferior to that of zinc, on the other hand they unite with mercury in virtue of so feeble an affinity that the formation of the alloy lowers the temperature, as is the case with tin and even with lead.
As to the metals analogous to cadmium which disengage heat during amalgamation, and which, according to theory, ought to be lower in the scale of affinities, their place in the group of metals is, through their electro-positive property, far removed from mercnry_
Their combination with mercury is the consequence of an energetic affinity, and as their fusing heat seems otherwise to be feeble, the heat produced during the reaction is of remarkable intensity.
Potassium and cadmium, the amalgamation of which is attended with the production of heat to the extent of incandescence, have suggested to me a new bearing of these ideas. Experiments, with results as precise as they are unvarying, have proved that the amalgams of potassium and sodium, formed by these powerful affinities, are negative relatively to pure metals. They present, then, the extreme limits of chemical and thermic phenomena as presented by cadmium. These phenomena will certainly be met with again in various metals of the first sections, the properties of which have been but imperfectly appreciated.
From these researches the following deductions may, in conclusion, be drawn:—
When a metal is amalgamated, its position in the scale of affinities undergoes some modification. The result may be in the contrary direction even for allied metals, for it depends both on the chemical function of the metal and on its latent heat of fusion.
If the temperature is lowered during the combination of the metal with mercury, if, consequently, the constitutional heat of the amalgam is greater than that of the metal, the latter is raised in the order of positive affinities.
When all the thermic phenomena are inverse, when heat is disengaged during the formation of the alloy, the amalgamated metal is negative, in relation to the free metal.—Comptes-Pendus.
On the Molecular Dissymmetry of Natural Organit Products, by L. Pastetjr, Member of the Chemical Society of Paris.
(Concluded from p. 149.)
X. Here is a very interesting application of tho facts which I have just submitted.
Seeing right and left tartaric acids become thus dissimilar solely in virtue of the rotary power of the base, there was room to hope that from this very dissemblance would result chemical forces capable of balancing the mutual affinity of these two acids, and consequently a chemical means of separating the two elements of paratartaric acid. I long sought without success; but I succeeded in it by the aid of two new bases,—isomerics of quinine and cinchonine,—and I obtain very easily, without the smallest loss, by the aid of these latter, quinicine and cinchonicine.
I prepare the paratartrate of cinchonicine by neutralising the base, then adding as much acid as was required for its neutralisation, I crystallised, and the first crystallisations are formed of left tartrate of cinchonicine perfectly pure. All the right tartrate remains in the liquid, because it is more soluble. Ihen itself is crystallised, and under a different aspect, because it has not the same crystalline form as the right [qy. left ?]. One would suppose that he had to deal with the crystallisation of two very distinct salts of unequal solubility.
XI. But the dissemblance of tho properties of corresponding right and left bodies, when submitted to dissymmetric forces, appears to me to be of the highest interest in connection with the ideas it suggests on the mysterious cause which presides over the dissymmetric disposition of atoms in natural organic substances. Why
this dissymmetry? why such a dissymmetry in preference to its inverse P
Recur with me in thought to the epoch when, having recognised the absolute identity of the physical and chemical properties of corresponding right and left bodies, I had no idea—not even a suspicion—of possible differences between these bodies. It is, indeed, manyyears since I recognised these identities and these differences.
It was then impossible for me to understand how Nature could make a right body without making at the same time a left body. For the same forces which are in play at the moment of the elaboration of the molecule of right tartaric acid, ought, it seems, to give a left molecule, and there should be only paratartarics.
Why even rights or lefts? Why not only non-dissymmetries, substances of the order of those of inorganic nature?
There are evidently causes for these curious manifestations of the play of molecular forces. To indicate them in a precise manner would be certainly very difficult; but 1 do not believe I am mistaken in saying that we know one of their essential characters. Is it not necessary and sufficient to admit that, at the moment of the elaboration in the vegetable organism of immediate principles, a dissymmetric force is present? For we have just seen there was but a single case in which the right molecules differed from their left,—the case in which they are submitted to actions of a dissymmetric order.
May these dissymmetric actions, placed perhaps under cosmic influences, reside in light, in electricity, in magnetism, in heat? Are thev in relation with the motion of the earth, with the electric currents by which physicists explain the terrestrial magnetic poles? It is not even possible, at the present time, to emit the smallest conjectures in this respect.
But I regard as necessary the conclusion, that dissymmetric forces exist at the moment of elaboration of natural organic products,—forces which would be absent or without effect in the reactions of our laboratories, either on account of the sudden action of these phenomena or on account of some other unknown circumstance.
XII. We come to the last experiment, the interest of which does not yield to any of those which precede, in the proof which it will manifestly afford us of the influence of dissymmetry on the phenomena of life. We have just seen dissymmetry intervene as a modifier of chemical affinities; but it dealt with reactions purely mineral and artificial, and we all know how prudent we should be in the application of results in our laboratories to the phenomena of life. Therefore, I have reserved almost all the views presented in this lecture until I recognised in the most certain manner that molecular dissymmetry offers itself as a modifier of chemical affinities, not only in the reactions of inorganic nature, but in. those of a physiological order in fermentations.
This is the remarkable phenomenon to which I allude. It has long been known, through the observation of a manufacturer of chemical products in Germany, that the impure tartrate of lime of the factories, soiled by organic matters, and abandoned under water in the spring, may ferment and yield different products.
That stated, I place in fermentation the common right tartrate of ammonia in the following manner:—I take the very pure crystallised salt, dissolve it, adding to the liquid a very limpid solution of albuminoid matters. One gramme of dry albuminoid matters is enough for 100 grammes of tartrate. Very often the liquid, placed in a stove, spontaneously ferments. I say very often;