Obrazy na stronie

Aug. 18, 1865.
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College of Physicians.

77 those complex bodies which we have designated as proxi- on the other hand, do we find that deoxidation tends to inate organic principles. As was observed by Gerhardt combine the separated carbon and hydrogen atoms into some twenty years ago, one of the two extremities of the more and more complex molecules. The organism of a scale of organic compounds is occupied by such bodies as plant, for instance, operating upon mono-carbon comalbumen, and gelatine, and fat, and cerebral matter ; the pounds only, effects simultaneously their deoxidation and other extremity by carbonic acid, and water, and ammonia; inter-combination. It deoxidates them with evolution while an infinity of bodies are included in the interval. of oxygen into the atmosphere, and combines the residual The chemist, by treating the superior substances with less oxygenated carbon and hydrogen into the various oxidising agents, gradually descends the scale of com- forms of vegetable tissue and secretion. What the plexity, converting these substances into more and more intermediate stages are between water and carbonic acid, simple products, by successively burning off a portion of on the one hand, and some vegetable principle such as their carbon and hydrogen.

mannite or sugar on the other, we cannot at present say, Thus, then, we have presented to us one important though our knowledge upon the subject is receiving daily aspect of organic chemistry, namely, its analytic or accessions. But be our acquaintance with the interdestructive aspect ; that aspect upon which, until of late mediate stages ever so imperfect, the final result is peryears, the attention of chemists was almost exclusively fectly intelligible. We know, for instance, that in the directed ; that aspect, indeed, which was at one time con production of this body, mannite, there has been a de sidered to be theonly possible aspect which could ever be pre-oxidation of six molecules of carbonic anhydride and sented. To quote again from the same distinguished chemist, seven molecules of water, and that in the course of the of whom I am always proud to avow myself a pupil: "Ideoxidation the thirteen separate molecules have been show," said Gerhardt, writing in 1842, • how the chemist conjoined into one single molecule, thus : does everything that is contrary to living nature-that he

Carbonic anhyd. Water. Oxygen. Mannite. burns, destroys, works by analysis —the vital force alone

6 CO, + 7 H,0 130 operates by synthesis and reconstructs the edifice destroyed

1 C H1406 by chemical forces.” But, in reality, there is another This, then, is the point which I wish to bring promi. side to the shield ; there is a constructive as well as a nently under your notice that while oxidation tends to destructive, a synthetic as well as an analytic, chemistry; the separation of atoms, and the formation of simple and to this view of the subject I will now'direct your out of complex bodies, deoxidation, as manifested in attention.

the vegetable kingdom, tends to the combination of atoms, I need scarcely remind you of the mode in which veget- to the formation of complex bodies out of simple ones. able structures are originally built up. The minute seed Now, the chemist in his laboratory can imitate, however grows into the gigantic tree, the great mass of which is crudely, the synthesis of nature. We find in the laboramade up of carbon, hydrogen, and oxygen, which the tory, as in the organism, that deoxidation, actual or living organism has stored up from the carbonic acid and potential, leads to the conjunction of atoms, and to the water with which it has been supplied throughout the building up. of complex molecules. In broad antagonism period of its existence, and which it has intercombined to the doctrines which only a few years back were reinto the various forms of vegetable tissuo. Now, this garded as indisputable, we now find that the chemist, like storing up of carbon, hydrogen, and oxygen, this forma- the plant, is capable of producing from carbonic acid and tion of vegetable compounds, is attended throughout by water a whole host of organic bodies, and we see no reason an evolution of oxygen. The proportion of oxygen con.

to question his ultimate capability to reproduce all animal tained in carbonic acid and water being greatly in excess

and vegetable principles whatsoever. of the proportion contained in vegetable tissue and secre

But for the production of certain organic principles, tion, we have throughout the growth of every plant a

whether by natural or artificial means, something more constant deoxidation of carbonic acid and water- the than carbonic acid and water is required. The albuminoid carbon, hydrogen, and necessary oxygen being retained in bodies, in particular, cannot be formed without nitrogen, the substance of the plant, the oxygen in excess of the and plants, in general, cannot grow without a supply of requirement of the plant being discharged into the atmo- ammonia or some transformable compound. You will sphere. Let me recall to your recollection one of the original observe, however, that ammonia, considered as a pabulum experiments of Priestley upon this subject

. He showed, for plants, differs in this important respect from both carfor example, that under exposure to sunlight a quickly bonic anhydride and water, that it is not susceptible of degrowing leafy plant, immersed in an atmosphere which by oxidation, so that the characteristic chemical action

of plantthe combustion of fuel, had been freed from oxygen and life cannot be exerted upon it. On the contrary, ammonia charged with carbonic acid, gradually restored that atmo- is the most thoroughly deoxidised, or rather hydrogenetted, sphere to its pristine condition, by an absorption and compound of nitrogen with which chemists are acquainted, subsequent decomposition

of its carbonic acid, into oxygen Even nitrogen itself may be looked upon as less deoxidised gas evolved from the leaves, and carbon retained within than ammonia, being intermediate between ammonia and the vegetable organism. Here we have an imitation of nitrous acid, thus :the experiment. A bunch of fresh mint has been thrust

Nitrogen molecules. into this narrow upright cylinder of dilute carbonic acid

HNOZ Nitric acid. water standing in the small pneumatic trough, and the

HNO, Nitrous acid. whole exposed to sunlight. You perceive that the leaves are

NN Nitrogen. now covered all over with minute beads of gas, and that

HZN Ammonia. a small but appreciable quantity of gas has collected at The nitric and nitrous acids being regarded as oxidised the top of the cylinder. By pulling the attached thread forms of nitrogen, ammonia may be regarded as a deosiI am able to withdraw the bunch of mint, and on now dised form, the element quoad its state of oxidation passing up a few bubbles of nitric oxide, a dark-brown being strictly intermediate between ammonia and nitrous Tapour is produced, proving the presence of oxygen in the acid, as I hope to render experimentally evident to you. gas which had accumulated at the top of the cylinder, Thus, on passing a series of electric sparks from the which oxygen, thus evolved by the growing plant, was Rühmkorff machine through the moist air contained in separated by the plant from the carbonic acid, or hydrated this apparently empty glass cylinder, a portion of the oxide of carbon, by which it was surrounded.

nitrogen of the contained air becomes gradually oxidised, Now, just as oxidation tends to separate the constituent and after a short time we shall see brown nitrous fumes carbon and hydrogen atoms of a complex organic mole- make their appearance. By allowing the experiment to cule so as to produce simpler and simpler molecules, so, I continue, the depth of colour in the cylirder wi go on

College of Physicians.


, . increasing so as to be visible all over the theatre. But I the other bodies. Organic compounds seem to consist of dare say I shall be able to render the nitrous acid already carbon, hydrogen, and oxygen only; whilst nitrogen exists produced abundantly manifest by allowing it to act upon therein but as the representative of ammonia on the one a piece of paper stencilled with starch and iodide of hand, or of nitric acid on the other.” In organic compotassium solution. That we have really obtained a con- pounds of natural origin, nitrogen occurs only as a residue siderable amount of nitrous acid, by the few sparks which of ammonia ; whilst in organic compounds of artificial have already passed through the air in the cylinder, is origin, it occurs sometimes as a residue of ammonia, as in shown by the speedy liberation of iodine from the iodide of cyanogen C,N,, sometimes as a residue of nitric acid, as in potassium, and consequent appearance of the word azobenzide C12!11.N.,. NITROUS in purple characters upon the prepared paper. In the artificial formation of organic compounds, then,

Now for the reverse experiment. In this flask is a mix- there are, as I have said, two distinct points for our ture of materials for generating hydrogen, namely, a consideration, namely, the building up of the primary little granulated zinc, iron borings, and warm solution of oxihydrocarbon molecules, and the combination of the potash. Active effervescence quickly takes place, and the residues of these constituent molecules with one another, evolved gas, which is without action upon turmeric paper, and with ammonia, to form complex organic principles. as you perceire, burns with the characteristic flame of Now, the power of combining the residues of aplone hydrogen. If we now absorb the brown nitrous fumes molecules with one another, so as to form more or less contained in this bottle, by agitation with aqueous potash, complex bodies, has been in the possession of chemists and pour the solution so obtained of nitrite and nitrate of from almost the earliest days of organic chemistry, and potassium into our hydrogen flask, you observe that the has been fully recognised to be in their possession. But, effervescence becomes more rapid, and that the evolved gas somewhat strangely, it is only of late years that this wellis now decidedly ammoniacal, as shown by its browning known power has been applied to the construction of some the turmeric paper and fuming with the hydrochloric acid of the most familiar components of animal and vegetable vapour I bring into its neighbourhood. The reaction bodies. It is only of late years, for instance, that chemists taking place is represented in this equation ;

have produced stearine, by putting together the residues Nitrous acid. Hydrogen. Water, Ammonia.

of glycerine and the fatty acid; or sarcocine, by putting HNO, + H. 21,0 + H2N

together the residues of acetic acid and methylamine; or 80 that not only is oxygen taken away from, but hydrogen acid and glycocine; or taurine, by putting together the

hippuric acid, by putting together the residues of benzoic is added to the nitrogen of our original nitrous acid.

residues of isethionic acid and ammonia, &c., as referred By combining the oxidised form of nitrogen, or nitrous to in my last

lecture. It must be observed, however, that acid HNO,, with the hydrogenetted form of nitrogen, or ammonia NË, we obtain nitrite of ammonia NH,HNO,, a

the neglect of these syntheses arose not so much from want

of interest in the production of the bodies, as from want neutral crystallisable, salt, whose somewhat concentrated of knowledge of their intimate constitution. No sooner, solution is contained in this flask-retort. Now, on apply for instance, was the constitution of these four compounds ing heat to the retort, observe what takes place. There satisfactorily made out than they were obtained artificially is, you see, a copious evolution of gas, some of which we will collect over the pneumatic trough, and, in order to save

by Berthelot, Volhard, Dessaignes, and Strecker and Kolbe time, will content ourselves with only a small cylinder will it be with many other complex tissue products, with

respectively; and as it has been with these, so doubtless full. The gas, produced in this manner from the nitrite the constitution of which we are as yet imperfectly of ammonia solution in the retort, is nitrogen, and accordingly you see it has the property of extinguishing flame.

acquainted. In this decomposition the hydrogen of the ammonia exactly however, or the building up of the primary oxihydro

T'he first stage of the process of organic synthesis, suffices to remove the excess of oxygen from the nitrous carbon molecules, was considered until very recently acid, whereby the nitrogen of both constituents of the salt | as altogether beyond the çrt of the chemist,

It used is simultaneously liberated, thus :

to be thought that chemistry was essentially incomAmmonia nitrite. Water. Nitrogen.

petent to the production not only of organised, but of NHHNO, 21,0 + N,

organic bodies. For the production of these bodies, the Hence nitrogen may be looked upon as exactly inter- intervention of some living organism, the expenditure of mediate in its state of oxidation between nitrous acid on some vital force--whaterer that might be-was considered the one hand, and ammonia on the other, while ammonia absolutely necessary. While the constituent atoms of a must be considered the extreme product of deoxidation. piece of alum, for instance, were admittedly, held together Accordingly, it has been found as a general result both of by mere mechanical and chemical forces, the atoms of a laboratory and field experiments, the latter conducted piece of sugar, on the other hand, or of a piece of fat, were more especially by Messrs. Lawes and Gilbert in this conceived to be put together in some mysterious way by country, that cereals and other plants thrive equally well vital forces. These opinions were originally propounded by upon salts of nitrous or nitric acid as upon salts of am- Berzelius at a time when perhaps the then state of knowmonia ; and that when a plant is supplied with water, ledge fully justified their enunciation. They remained carbonic acid, and nitrous acid, it exerts upon the nitrous almost unchallenged for a long series of years, and are still acid the same sort of reducing action that it does upon the asserted in some recent text-books with a degree of dogcarbonic acid and water, whereby not only farinaceous, matism altogether opposed to the present adsanced state hea but ammoniated or nitrogenised principles are abundantly of knowledge on the subject. produced ; while some chemists have even maintained The great progress recently made in the constructive art of that nitrous acid, rather than ammonia, forms the normal the chemist is, I think, a topic of sufficient interest to sarrant nitrogenous food of plants.

me in entering into further detail upon the heretofore-preBe this as it may, in all animal and vegetable nitrogeinsed vailing opinions, which I find expressed very well in the products of which the constitution is understood we know, last edition but one of Liebig's Chemical Letter«, the last and in all other nitrogenised principles have good reason edition that was translated by Dr. Gregory, who, writing to believe, that the constituent nitrogen exists as a group in 1851, says :-"We are able to construct a crystal of apart—as a residue of, or proxy for, ammonia-ready on alum 1rom its elements, namely, sulphur, oxygen, hydrothe occurrence of suitable conditions to regenerate that gen, potassium, and aluminum, inasmuch as heat as well ammonia. As was observed by Laurent some ten years as chemical affinity are, within a certain limit, at our free ago, " nitrogen does not enter into the constitution of disposal, and thus we can determine the manner of organic substances on the same footing, so to speak, as do arrangement of the simple and compound elements. But


Aug. 18, 1865.

College of Physicians.


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we cannot make an atom of sugar from the elements of have previously said, there is now no reason to doubt our sugar, because in their aggregation into the characteristic capability of producing all organic principles whatsoever form of a sugar atom, the vital force co-operates, which is in a similar manner. Wöhler's artificial production of not within the reach of our control, as heat, light, the urea from cyanate of ammonia in 1828, and Pelouze's force of gravity, &c., are to a certain extent.

artificial production of formic from hydrocyanic acid in We may produce atoms of a higher order by combining 1831, were in reality very important pioneering achievetwo, three, four, or more compound organic atoms ; we ments, although cyanogen and its compounds were at that can decompose the more complex into less complex com- time known only as products of the decomposition of pound atoms ; we can produce sugar from wood or starch, organic bodies. But in 1845 Kolbe produced acetic and from sugar we can produce oxalic acid, lactic acid, acid from carbon by a series of strictly inorganic probutyric acid, acetic acid, aldehyde, alcohol, formic acid, cesses, and thereby laid the foundation of modern syn&c., although we are altogether incapable of producing thetic chemistry. He observed in his paper on the subject any of these compounds by a direct combination of their —“From the foregoing observations we deduce the inelements."

teresting fact that acetic acid, hitherto known only as I might further refer you to Dr. Gregory's deservedly- a product of the oxidation of organic materials, can be popular Handbook, of which the last edition appeared in built up by almost direct synthesis from its elements. . 1857, and to many other works, as showing the general If we could only transform acetic acid into alcohol, and prevalence of these opinions, but content myself with out of the latter could obtain sugar and starch, then we extracting the following series of passages from the most should be enabled to build up these common vegetable recent of all our chemical text-books. You will see that principles, by the so-called artificial method, from their in this work, published only two years ago, the statements most ultimate elements." Relying upon these results, made by Liebig in 1851, and by older chemists long Laurent in his " Methode de Chemie," 1853, and Hofbefore then, are substantially reiterated. “ Organic mann in a course of lectures “ On Organic Chemistry," chemistry is that branch of the science which refers to delivered the same year at the Royal Institution, the the properties and composition of organised products, or latter, with very great detail, showed how impossible it of substances which have been formed in vegetables and was to draw the line of demarcation between carbon comanimals under the influence of life.

The pounds of organic, and carbon compounds of mineral origin. products, or those substances which result from artificial They both referred to Kolbe's formation from mineral processes, are far more numerous than the educts, or proxi- elements of acetic acid or vinegar, and of certain highly mate principles of which organic compounds are considered complex bodies procurable from vinegar, such as mesidine to be formed. These educts, which, as their name implies, C,H3N, and nitro-mesidine C,

UN,O,. It must be may be extracted in an unaltered state, are the immediate admitted, however, that to the labours of Berthelot, or proximale principles of the vegetable or animal structure. prosecuted unintermittingly for the last ten years, is

Some bodies which exist r.aturally in the due that full recognition of synthetic organic chemistry vegetable structure, and are regarded as educts, may be which now obtains, and the very great advances which have artificially produced by a reaction of mineral on organic recently been made therein, both by himself and by others, substances. In all cases, however, either an organic sub- which I propose hereafter to bring under your more stance or a body derived from the organic kingdom is especial consideration. indispensable to this conversion.

The principal Before proceeding, however, to exemplify the powers of sources of hydrocyanic acid are certain metallic cyanides. organic synthesis in the artificial formation of animal and But these compounds have an organic origin; they are the vegetable products from carbon, hydrogen, and oxygen, I products of a reaction of organic upon inorganic sub- must beg leave to make a rather long digression. I prostances; hence the production of hydrocyanic acid by pose, firstly, to brirg before you some elementary experitheir decomposition furnishes no exception to the remark ments connected with the productiou and decomposition above made. Under this point of view, the production of the oxides of carbon and hydrogen, or carbonic anhyof artificial urea from hydrated cyanate of ammonia is dride CO2, and water H,O, respectively; and then to consimply a conversion of cyanic acid (a derivative of an sider with you what bearing these experiments have upon organic substance) into another organic compound. By the forces exerted in animal and vegetable life, or, in other no processes yet known can gum, starch, or sugar be pro. words, upon the so-called vital forces. duced from their elementary constituents C,H,O; and by I have here an ordinary form of apparatus in which the production of alcohol from a mixture of sulphuric hydrogen gas is being generated in the usual manner from acid, olefiant gas, and water, Berthelot has merely proved zinc and dilute sulphuric acid, and dried by transmission that a hydrocarbon of organic origin or one derived from through oil of vitriol. On burning the jet of dried hydrogen organic matter is capable of being converted into another under this cold bell jar, we observe that the interior of organic product.” Thus the view very generally enter the jar becomes quickly corered with a film of condensed tained but a few years back was substantially this-that steam or water, produced by the direct combustion of the the chemist could not produce organic out of mineral hydrogen gas with the oxygen of the air. Now, by promatter; he might transform one kind of organic matter gerly contrived experiments, I might show you that the into some allied kind of organic matter-starch into sugar, weight of water produced in this way is exactly equal to and olefiant gas into alcohol, for instance; he might pro- the weight of oxygen and hydrogen consumed in the duce certain simple organic principles by the breaking up of burning. But during the combustion there is a produc, more complex molecules - oil of spirea, for instance, from tion not only of water but of heat, which I may exhibit salicine, alcohol from sugar, and glycerine from fat; and he to you in a more striking manner. We have here a might even produce highly complex principles, by a con- piece of clean platinum foil, which is now maintained junction of two or more simple principles-oil of winter in a state of ignition by the hydrogen flame. I turn off green by combining salicylic acid with wood spirit, and the supply of hydrogen for a minute or so, and before fat by combining stearic acid, for instance, with glycerine; the platinum has become quite cold, turn it on again, but this was the limit of his powers—he might shuffle about when you observe that the metal becomes and con. the residues of existing organic compounds in a variety of tinues 'redhot without inflaming the gas. The mixed ways, but was utterly unable to produce even the simplest hydrogen and air on the surface of the foil combine with of them by elemental synthesis. Our present knowledge, one another to form water, and at the same time produce however, assures that these opinions are altogether without an amount of heat sufficient to maintain the metal in a foundation. Already hundreds of organic principles have state of visible ignition. But where does this heat come been built up from their constituent elements, and as I from? We have a production of heat and a production of

seny P

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Aug. 18, 1865. water ; ought we not to account for the one as intelligibly itself producible, as I have shown you, from the direct as we can for the other :

combustion of charcoal in air or oxygen. By combining I now take a piece of charcoal, and make it red-hot in hydrogen and oxygen with one another we obtain water, the Bunsen gas Aame. Here I have a bottle of oxygen, and by acting upon the water with a deoxidising agent we into which we will pour a little lime water to show get back the hydrogen. Similarly, by combining carbon the result of the ac:ion, and now that the piece of and oxygen with one another we obtain carbonic anhy. charcoal is sufficiently heated, I introduce it into the dride, and by acting upon the carbonic anhydride with the bottle of oxygen, when combination between the carbon same deoxidising agent we get back the carbon, as you and oxygen takes place, as you perceive, with vivid com- perceive. When we acted upon oxide of hydrogen with bustion In this experiment we have, then, carbonic sodium, we separated the oxygen and obtained the hydroanhydride or di-oxide of carbon produced, the source of gen; when we acted upon oxide of carbon with sodium we which is perfectly evident. Upon shaking up the clear separated the oxygen and obtained the carbon. Now the lime water which we previously introduced, that which was living plant effects a similar decomposition of these two soluble hydrate of calcium becomes insoluble carbonate of compounds, but in a gradual manner, which we shall herecalcium or chalk, and accordingly we now have, as you after endeavour to imitate. The plant absorbs oxide of see, a considerable white turbidity produced. If instead hydrogen or water, and oxide of carbon or carbonic anhyof absorbing the carbonic anhydride by lime water in this dride, deoxidises both compounds to a more or less commanner, we were directly or indirectly to weigh it, we plete extent, evolves the separated oxygen into the atmo. should find that its weight was exactly equal to that of sphere, and retains the united carbon and hydrogen, with the carbon burnt, plus that of the oxygen which served or without some oxygen, in the form of vegetable tissue or to burn it. But, in addition to carbonic anhydride, there secretion. When the tissue or secretion is subjected to a was during the combination an abundant production of full red heat it. yields, among other products, free carbon, light and heat. Now the axiom, that out of nothing comes free hydrogen, and various compounds of carbon with nothing, is just as true of light and heat as of water and hydrogen. The piece of wood-charcoal now in my hand, carbonic anhydride. We have no difficulty in understand for instance, has resulted indirectly from a gradual deoxidaing the production of the carbonic anhydride; what, how- tion of carbonic anhydride by the living plant, just as this ever, is the origin of the light and heat ?

piece of charcoal in the flask has resulted directly from a So much, then, for the formation of oxide of hydrogen violent deoxidation of carbonic anhydride by the metallic or water, and oxide of carbon or carbonic anhydride ; now sodium. for their decompositions. By a variety of means we are Thus, then, we have presented to our notice the most able to separate hydrogen and carbon from their re- important terrene, or rather cosmical function of plant life. spective combinations with oxygen; one of the most con- The living plant effects a decomposition of carbonic anhyvenient materials for the purpose being inetallic sodium. dride and water, evolves the liberated oxygen, and retains If, for instance, we introduce under this vessel of water a within its organism the united carbon and hydrogen, piece of metallic sodium, which, for the sake of con- which becoming the food of animals, are simultaneously venience, I have diluted with a little mercury, so that the disunited and re-oxidised once more into carbonic anhyreaction may take place more slowly than it otherwise dride and water. Now, I wish to consider with you-would, we get, as you perceive, a regular evolution of I was going to say more minutely, but I should rather hydrogen gas. The sodium combines with the oxygen say more broadly-what is the essence of these compli. of the water, whilst its hydrogen is set at liberty ; and mentary actions in their relation to the first principles of in a similar manner we may liberate carbon from car- that dynamical philosophy which is now often spoken bonic anhydride, as I will now endeavour to show you. of as the science of energetics. It formed part of my ori. The carbonic anhydride produced by the combustion of a ginal plan to give a passing glance at this subject, but I piece of charcoal in this bottle of oxygen was absorbed by certainly should not have ventured to discuss it in the means of lime, whereby we obtained a precipitate of alk, elementary form in which I now propose to bring it from which by treatment with hydrochloric acid we may under your notice, had it not recently come to my knoweasily re-obtain the carbonic anhydride. Thus, if I transfer ledge that certain principles of mechanical philosophy our mixture of chalk and water into this narrow cylinder admitted by that class of naturalists who are called phy. standing over the mercurial trough, and then pass up a sicists to be as fundamental as the law of gravitation little hydrochloric acid, you observe that the chalk dis- itself, are not generally acknowledged by that other class appears with effervescence, while a quantity of gas collects of naturalists who are called physicians. Now, in order at the top of the cylinder, which is the carbonic anhydride to contrast with one another the great antagonistic funcgas we lately produced in this bottle by the direct combina- tions of plants and animals, the decomposition of carbonic tion of carbon and oxygen. In the arrangement on the table anhydride and water by the one class, and recomposition before you we are producing a current of carbonic anhydride of carbonic acid and water by the other, it would not conin a similar manner by acting upon chalk or, rather, marble, duce to my object, even if it were within my competency, with dilute hydrochloric acid. The gas evolved in the to discuss with you the simplest functions of organic life, Wolfe's bottle is transmitted over pumice and oil of vitriol as manifested in the most minute and simple organisms, to render it dry, and then conveyed to the bottom of an or- in some of which it is scarcely possible for us to disdinary Florence flask, into which I have dropped a piece of tinguish between the animal or vegetable character. Feel. clean metallic sodium. We now apply a large blowpipe ing that every phase of life deserves our attentive exaflame to the bottom of the flask so as to heat the contained mination, I am far from insensible to the advantages sodium. There is a little practical difficulty in starting attending the study of its most elementary forms. But the reaction, and perhaps the experiment may not succeed this study cannot, I maintain, teach us the whole truth. at the first trial, but it is sure to succeed sooner or later. There are principles of the highest importance which can The action is now beginning, and you observe the piece of only be learned by having regard to the directions in sodium glowing in the flask. The glowing is soon suc- which animal and vegetable life respectively tend-- by comceeded by a brilliant combustion, attended by the forma paring with another the highly specialised forms of animal tion of copious white fumes. The sodium has effected a and vegetable life, not in their minute details, but in their decomposition of some of the carbonic anhydride, united broad general features. In my next lecture, then, we shall with its oxygen to form soda, and liberated its carbon in have to consider more especially what is the nature of the the form of a black mass, which remains, as you see, at the force exerted in the characteristic actions of vegetable and bottom of the flask. This piece of charcoal in the flask animal life-whether we have to do with some peculiar has been extracted from carbonic anhydride gas, which is internal vital force, or only with the ordinary external

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forces of nature, working in a manner strictly parallel to that in which they are habitually exerted in the inorganic


Chemistry as a Branch of General and Practical Education.

By Dr. T. Wood, F.C.S. (Reprinted from the Social

Science Review.) London : Hutchinson. 1865.
August 7.

We cannot say that we are struck by either Dr. Wood's M. CLOEz communicated a memoir entitled " Experiments matter or style, or, indeed, anything that is exclusively and Observations on Fally Matters of Vegetable Origin.” | his, though we of course share his opinion that it is The author's experiments were principally directed to extremely desirable that, at all events, the elements of a ascertain the nature of the changes produced in drying science which receives more practical applications in everyoils by the action of air and oxygen. He first analysed day life than any other should form a part of every boy's various oils, and then exposed to air and light at the and even girl's education. ordinary temperature 10 grammes of each oil in flat glass Dr. Wood very correctly remarks that school is the dishes lightly covered with unsized paper. The dishes place where the foundation of a scientific training must were weighed every three months, to ascertain changes in be laid, and for this reason advocates early instruction in weight. The whole time of exposure was eighteen chemistry. “ The real use," (he says in another place) months, and in this time M. Cloez found an increase of " and value of chemistry to boys as compared with other weight in erery instance, but varying from 2'5 to 8.5 per subjects of education is a matter of opinion, though it is of cent. It is remarked, however, that the increase was not great importance at the present time, especially on account of constantly progressive during the whole time. At certain the Government inquiries into matters of education." times there was a diminution of weight, so that if the We may here leave Dr. Wood to give some of the phenomenon was represented graphically, there would be a results of the Government inquiries. The Select Comcurve gradually rising to a certain maximum, then slowly mittee of the House of Lords on the Public Schools Bill falling to end by becoming parallel to the axis of the put the three following questions to Professors Huxley and abscissa, but this only after a great lapse of time. The Tyndall ; Dr. W. A. Miller, and Dr. W. Sharpey-viz. :author shows that it is a simple oxidation that takes Question 1.--"In what branches of physical science place. The amount of carbonic acid produced does not should instruction be given in our public schools, and represent a quarter of the carbon that disappears. The what branches, if any, should be excluded ?" remainder forms volatile compounds with hydrogen and Question 2.-" In what manner should that instruction oxygen, among which he proved the presence of acetic be imparted ; should there be periodical examinations of and acrylic acids, and a small quantity of anoleine. The the pupils, and prizes for proficiency; and by whom white paper covering the dishes became brown after a should such examinations be conducted, and such prizes time, owing to the action of the volatile compounds awarded ?" formed. He believes the brown colour of the leaves of Question 3 ." Should instruction in science be made old books to be owing to the slow oxidation of the oil in the imperative by positive enactment, and if not, in what printer's ink. M. Cloez gives a table of the amount of oil mode should it be promoted and encouraged by the Legisin

on on a future occasion.

that he is strongly in favour of confining instruction in M. Dancel presented a memoir “ On the Influence of science for disciplinal purposes to elementary physics Water in the Production of Milk.The author has noticed (with incidental chemistry) and botany, with the addition that women, when suckling, drink a great deal more than of the outlines of human physiology. A boy well grounded at other times. Cows, too, before they drop a calf will be in the rudiments of these sciences would find none of the satisfied with from 12 to 20 litres of water a-day, but methods and very few of the conceptions of the others afterwards they require 30, 40, or so litres. He notices absolutely strange. also that cows fed in houses on dry food give a fourth or In reply to the second the Professor says that the most eren a third less milk than when at pasture. He states, perfect method of teaching science is that pursued by too, that cows fed upon dry sesame cake gave very little anatomists, and chemists, who combine lectures with pracmilk until they were freely supplied with water. He tical demonstrations, and he very properly insists that concludes from all this that water has a good deal to do University rewards should be open to boys who show with the secretion of milk.

special aptitude for scientific research. M. Bechamp read a paper “ On Variations in the Amount

Dr. Tyndall is no less explicit in his answers.

He conof Nefrozymase present in Urine in Different States of the tends that instruction should be given in elementary Body.' Nefrozymase is the soluble ferinent discovered by physics, comprising under this term the phenomena and the author in healthy urine. (See CHEMICAL News, vol. xi., laws of gravity, light, heat, sound, electricity, magnetism, p. 116.) The author finds that the proportion of this body and the mechanical properties of air and water. is increased by violent exercise. In patients labouring The first principles of chemistry ought also to be taught under Bright's disease, and in some cases of paraplegia, in our public schools. it disappears altogether. In advanced diabetes the amount Instruction in these subjects should, in his opinion, be is somewhat increased. Other pathological states seem to rendered imperative. influence the proportion; but the matter evidently requires He too advocates lectures and demonstrations, but does further investigation before the value of the determinations not at present recommend laboratories and practical can be estimated. The author states the urine of men con- instruction. tains more than that of women; and in every case the Dr. Miller's replies we give at length :urine of the blood-that is to say, that secreted at night- “ Answer to Question 1.-I consider that instruction contains the most. M. Bechamp also states that albumen should be given in Mechanics, including the principle of may be passed in the urine in two forms-one coagulable the composition and resolution of forces-centre of gravity, by heat and alcohol, and then remaining insoluble in the mechanical powers, the laws of motion. water; the other, not coagulable by heat, but precipitated “2nd. Hydrostatics and Pneumatics, including the by alcohol and soluble after precipitation. This soluble principle of fluid pressure, specific gravity, construction albugien differs from nefrozymase by having no action on of the barometer, the air pump, common pump, and forcing starch paste, which, our readers will remember, is lique- pump: the siphon. fied and changed into glucose by nefrozymase.

3rd. Optics, including the general nature of light ;

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