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those complex bodies which we have designated as proximate organic principles. As was observed by Gerhardt some twenty years ago, one of the two extremities of the scale of organic compounds is occupied by such bodies as albumen, and gelatine, and fat, and cerebral matter; the other extremity by carbonic acid, and water, and ammonia; while an infinity of bodies are included in the interval. The chemist, by treating the superior substances with oxidising agents, gradually descends the scale of complexity, converting these substances into more and more simple products, by successively burning off a portion of their carbon and hydrogen.

Thus, then, we have presented to us one important aspect of organic chemistry, namely, its analytic or destructive aspect; that aspect upon which, until of late years, the attention of chemists was almost exclusively directed; that aspect, indeed, which was at one time considered to be the only possible aspect which could ever be presented. To quote again from the same distinguished chemist, of whom I am always proud to avow myself a pupil: "I show," said Gerhardt, writing in 1842, "how the chemist does everything that is contrary to living nature-that he burns, destroys, works by analysis-the vital force alone operates by synthesis and reconstructs the edifice destroyed by chemical forces." But, in reality, there is another side to the shield; there is a constructive as well as a destructive, a synthetic as well as an analytic, chemistry; and to this view of the subject I will now direct your

attention.

on the other hand, do we find that deoxidation tends to
combine the separated carbon and hydrogen atoms into
more and more complex molecules. The organism of a
plant, for instance, operating upon mono-carbon com-
pounds only, effects simultaneously their deoxidation and
inter-combination. It deoxidates them with evolution
of oxygen into the atmosphere, and combines the residual
less oxygenated carbon and hydrogen into the various
forms of vegetable tissue and secretion. What the
intermediate stages are between water and carbonic acid,
on the one hand, and some vegetable principle such as
mannite or sugar on the other, we cannot at present say,
though our knowledge upon the subject is receiving daily
accessions. But be our acquaintance with the inter-
mediate stages ever so imperfect, the final result is per-
fectly intelligible. We know, for instance, that in the
production of this body, mannite, there has been a de-
oxidation of six molecules of carbonic anhydride and
seven molecules of water, and that in the course of the
deoxidation the thirteen separate molecules have been
conjoined into one single molecule, thus:
Carbonic anhyd. Water. Oxygen.

Mannite.

6 CO, +7 H,O - 13 O 1 CH1406 This, then, is the point which I wish to bring prominently under your notice that while oxidation tends to the separation of atoms, and the formation of simple out of complex bodies, deoxidation, as manifested in the vegetable kingdom, tends to the combination of atoms, the formation of complex bodies out of simple ones. Now, the chemist in his laboratory can imitate, however crudely, the synthesis of nature. We find in the laboratory, as in the organism, that deoxidation, actual or potential, leads to the conjunction of atoms, and to the building up of complex molecules. In broad antagonism to the doctrines which only a few years back were regarded as indisputable, we now find that the chemist, like the plant, is capable of producing from carbonic acid and water a whole host of organic bodies, and we see no reason to question his ultimate capability to reproduce all animal and vegetable principles whatsoever.

But for the production of certain organic principles, whether by natural or artificial means, something more than carbonic acid and water is required. The albuminoid bodies, in particular, cannot be formed without nitrogen, and plants, in general, cannot grow without a supply of ammonia or some transformable compound. You will observe, however, that ammonia, considered as a pabulum for plants, differs in this important respect from both carbonic anhydride and water, that it is not susceptible of deoxidation, so that the characteristic chemical action of plantlife cannot be exerted upon it. On the contrary, ammonia is the most thoroughly deoxidised, or rather hydrogenetted, compound of nitrogen with which chemists are acquainted. Even nitrogen itself may be looked upon as less deoxidised than ammonia, being intermediate between ammonia and nitrous acid, thus:

I need scarcely remind you of the mode in which veget-to able structures are originally built up. The minute seed grows into the gigantic tree, the great mass of which is made up of carbon, hydrogen, and oxygen, which the living organism has stored up from the carbonic acid and water with which it has been supplied throughout the period of its existence, and which it has intercombined into the various forms of vegetable tissue. Now, this storing up of carbon, hydrogen, and oxygen, this formation of vegetable compounds, is attended throughout by an evolution of oxygen. The proportion of oxygen contained in carbonic acid and water being greatly in excess of the proportion contained in vegetable tissue and secretion, we have throughout the growth of every plant a constant deoxidation of carbonic acid and water-the carbon, hydrogen, and necessary oxygen being retained in the substance of the plant, the oxygen in excess of the requirement of the plant being discharged into the atmosphere. Let me recall to your recollection one of the original experiments of Priestley upon this subject. He showed, for example, that under exposure to sunlight a quickly. growing leafy plant, immersed in an atmosphere which by the combustion of fuel, had been freed from oxygen and charged with carbonic acid, gradually restored that atmosphere to its pristine condition, by an absorption and subsequent decomposition of its carbonic acid, into oxygen gas evolved from the leaves, and carbon retained within the vegetable organism. Here we have an imitation of the experiment. A bunch of fresh mint has been thrust into this narrow upright cylinder of dilute carbonic acid water standing in the small pneumatic trough, and the whole exposed to sunlight. You perceive that the leaves are now covered all over with minute beads of gas, and that a small but appreciable quantity of gas has collected at the top of the cylinder. By pulling the attached thread I am able to withdraw the bunch of mint, and on now passing up a few bubbles of nitric oxide, a dark-brown vapour is produced, proving the presence of oxygen in the gas which had accumulated at the top of the cylinder, which oxygen, thus evolved by the growing plant, was separated by the plant from the carbonic acid, or hydrated oxide of carbon, by which it was surrounded.

Now, just as oxidation tends to separate the constituent carbon and hydrogen atoms of a complex organic molecule so as to produce simpler and simpler molecules, so,

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The nitric and nitrous acids being regarded as oxidised forms of nitrogen, ammonia may be regarded as a deoxidised form, the element quoad its state of oxidation being strictly intermediate between ammonia and nitrous acid, as I hope to render experimentally evident to you.

Rühmkorff machine through the moist air contained in Thus, on passing a series of electric sparks from the this apparently empty glass cylinder, a portion of the nitrogen of the contained air becomes gradually oxidised, and after a short time we shall see brown nitrous fumes make their appearance. By allowing the experiment to continue, the depth of colour in the cylinder wi go on

increasing so as to be visible all over the theatre. But I dare say I shall be able to render the nitrous acid already produced abundantly manifest by allowing it to act upon a piece of paper stencilled with starch and iodide of potassium solution. That we have really obtained a considerable amount of nitrous acid, by the few sparks which have already passed through the air in the cylinder, is shown by the speedy liberation of iodine from the iodide of potassium, and consequent appearance of the word NITROUS in purple characters upon the prepared paper.

Now for the reverse experiment. In this flask is a mixture of materials for generating hydrogen, namely, a little granulated zinc, iron borings, and warm solution of potash. Active effervescence quickly takes place, and the evolved gas, which is without action upon turmeric paper, as you perceive, burns with the characteristic flame of hydrogen. If we now absorb the brown nitrous fumes contained in this bottle, by agitation with aqueous potash, and pour the solution so obtained of nitrite and nitrate of potassium into our hydrogen flask, you observe that the effervescence becomes more rapid, and that the evolved gas is now decidedly ammoniacal, as shown by its browning the turmeric paper and fuming with the hydrochloric acid vapour I bring into its neighbourhood. The reaction taking place is represented in this equation;

Nitrous acid. Hydrogen. Water. Ammonia.
HNO, + H 2H2O+ H2N

so that not only is oxygen taken away from, but hydrogen
is added to the nitrogen of our original nitrous acid.
By combining the oxidised form of nitrogen, or nitrous
acid HNO2, with the hydrogenetted form of nitrogen, or am-
monia NÍ,, we obtain nitrite of ammonia NH,HNO2, a
neutral crystallisable salt, whose somewhat concentrated
solution is contained in this flask-retort. Now, on apply
ing heat to the retort, observe what takes place. There
is, you see, a copious evolution of gas, some of which we
will collect over the pneumatic trough, and, in order to save
time, will content ourselves with only a small cylinder
full. The gas, produced in this manner from the nitrite
of ammonia solution in the retort, is nitrogen, and accord-
ingly you see it has the property of extinguishing flame.
In this decomposition the hydrogen of the ammonia exactly
suffices to remove the excess of oxygen from the nitrous
acid, whereby the nitrogen of both constituents of the salt
is simultaneously liberated, thus:-

Ammonia nitrite. Water.

=

Nitrogen. NHHNO. 2H2O + N2 Hence nitrogen may be looked upon as exactly intermediate in its state of oxidation between nitrous acid on the one hand, and ammonia on the other, while ammonia must be considered the extreme product of deoxidation. Accordingly, it has been found as a general result both of laboratory and field experiments, the latter conducted more especially by Messrs. Lawes and Gilbert in this country, that cereals and other plants thrive equally well upon salts of nitrous or nitric acid as upon salts of ammonia; and that when a plant is supplied with water, carbonic acid, and nitrous acid, it exerts upon the nitrous acid the same sort of reducing action that it does upon the carbonic acid and water, whereby not only farinaceous, but ammoniated or nitrogenised principles are abundantly produced; while some chemists have even maintained that nitrous acid, rather than ammonia, forms the normal nitrogenous food of plants.

Be this as it may, in all animal and vegetable nitrogeinsed products of which the constitution is understood we know, and in all other nitrogenised principles have good reason to believe, that the constituent nitrogen exists as a group apart as a residue of, or proxy for, ammonia-ready on the occurrence of suitable conditions to regenerate that ammonia. As was observed by Laurent some ten years ago, nitrogen does not enter into the constitution of organic substances on the same footing, so to speak, as do

the other bodies. Organic compounds seem to consist of cat bon, hydrogen, and oxygen only; whilst nitrogen exists therein but as the representative of ammonia on the one hand, or of nitric acid on the other." In organic compounds of natural origin, nitrogen occurs only as a residue of ammonia; whilst in organic compounds of artificial origin, it occurs sometimes as a residue of ammonia, as in cyanogen C2N,, sometimes as a residue of nitric acid, as in azobenzide C12H10N.

In the artificial formation of organic compounds, then, there are, as I have said, two distinct points for our consideration, namely, the building up of the primary oxihydrocarbon molecules, and the combination of the residues of these constituent molecules with one another, and with ammonia, to form complex organic principles. Now, the power of combining the residues of aplone molecules with one another, so as to form more or less complex bodies, has been in the possession of chemists from almost the earliest days of organic chemistry, and has been fully recognised to be in their possession. But, somewhat strangely, it is only of late years that this wellknown power has been applied to the construction of some of the most familiar components of animal and vegetable bodies. It is only of late years, for instance, that chemists have produced stearine, by putting together the residues of glycerine and the fatty acid; or sarcocine, by putting together the residues of acetic acid and methylamine; or acid and glycocine; or taurine, by putting together the hippuric acid, by putting together the residues of benzoic residues of isethionic acid and ammonia, &c., as referred to in my last lecture. It must be observed, however, that the neglect of these syntheses arose not so much from want of knowledge of their intimate constitution. No sooner, of interest in the production of the bodies, as from want for instance, was the constitution of these four compounds satisfactorily made out than they were obtained artificially by Berthelot, Volhard, Dessaignes, and Strecker and Kolbe will it be with many other complex tissue products, with respectively; and as it has been with these, so doubtless the constitution of which we are as yet imperfectly acquainted.

however, or the building up of the primary oxihydroThe first stage of the process of organic synthesis, carbon molecules, was considered until very recently as altogether beyond the art of the chemist. It used to be thought that chemistry was essentially incompetent to the production not only of organised, but of organic bodies. For the production of these bodies, the intervention of some living organism, the expenditure of some vital force--whatever that might be-was considered absolutely necessary. While the constituent atoms of a piece of alum, for instance, were admittedly held together by mere mechanical and chemical forces, the atoms of a piece of sugar, on the other hand, or of a piece of fat, were conceived to be put together in some mysterious way by vital forces. These opinions were originally propounded by Berzelius at a time when perhaps the then state of knowledge fully justified their enunciation. They remained almost unchallenged for a long series of years, and are still asserted in some recent text-books with a degree of dogmatism altogether opposed to the present advanced state hea of knowledge on the subject.

The great progress recently made in the constructive art of the chemist is, I think, a topic of sufficient interest to warrant me in entering into further detail upon the heretofore-prevailing opinions, which I find expressed very well in the last edition but one of Liebig's Chemical Letters, the last edition that was translated by Dr. Gregory, who, writing in 1851, says :- We are able to construct a crystal of alum from its elements, namely, sulphur, oxygen, hydrogen, potassium, and aluminum, inasmuch as heat as well as chemical affinity are, within a certain limit, at our free disposal, and thus we can determine the manner of arrangement of the simple and compound elements. But

tur pp 496-499 Ams. Ed.

we cannot make an atom of sugar from the elements of sugar, because in their aggregation into the characteristic form of a sugar atom, the vital force co-operates, which is not within the reach of our control, as heat, light, the force of gravity, &c., are to a certain extent. We may produce atoms of a higher order by combining two, three, four, or more compound organic atoms; we can decompose the more complex into less complex compound atoms; we can produce sugar from wood or starch, and from sugar we can produce oxalic acid, lactic acid, butyric acid, acetic acid, aldehyde, alcohol, formic acid, &c., although we are altogether incapable of producing any of these compounds by a direct combination of their elements."

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I might further refer you to Dr. Gregory's deservedlypopular Handbook, of which the last edition appeared in 1857, and to many other works, as showing the general prevalence of these opinions, but content myself with extracting the following series of passages from the most recent of all our chemical text-books. You will see that in this work, published only two years ago, the statements made by Liebig in 1851, and by older chemists long before then, are substantially reiterated. Organic chemistry is that branch of the science which refers to the properties and composition of organised products, or of substances which have been formed in vegetables and animals under the influence of life. . The products, or those substances which result from artificial processes, are far more numerous than the educts, or proximate principles of which organic compounds are considered to be formed. These educts, which, as their name implies, may be extracted in an unaltered state, are the immediate or proximate principles of the vegetable or animal structure. .. Some bodies which exist naturally in the vegetable structure, and are regarded as educts, may be artificially produced by a reaction of mineral on organic substances. In all cases, however, either an organic substance or a body derived from the organic kingdom is indispensable to this conversion. The principal sources of hydrocyanic acid are certain metallic cyanides. But these compounds have an organic origin; they are the products of a reaction of organic upon inorganic substances; hence the production of hydrocyanic acid by their decomposition furnishes no exception to the remark above made. Under this point of view, the production of artificial urea from hydrated cyanate of ammonia is simply a conversion of cyanic acid (a derivative of an organic substance) into another organic compound. By no processes yet known can gum, starch, or sugar be produced from their elementary constituents C,H,O; and by the production of alcohol from a mixture of sulphuric acid, olefiant gas, and water, Berthelot has merely proved that a hydrocarbon of organic origin or one derived from organic matter is capable of being converted into another organic product." Thus the view very generally enter tained but a few years back was substantially this-that the chemist could not produce organic out of mineral matter; he might transform one kind of organic matter into some allied kind of organic matter-starch into sugar, and olefiant gas into alcohol, for instance; he might produce certain simple organic principles by the breaking up of more complex molecules-oil of spirea, for instance, from salicine, alcohol from sugar, and glycerine from fat; and he might even produce highly complex principles, by a conjunction of two or more simple principles-oil of wintergreen by combining salicylic acid with wood spirit, and fat by combining stearic acid, for instance, with glycerine; but this was the limit of his powers-he might shuffle about the residues of existing organic compounds in a variety of ways, but was utterly unable to produce even the simplest of them by elemental synthesis. Our present knowledge, however, assures that these opinions are altogether without foundation. Already hundreds of organic principles have been built up from their constituent elements, and as I

have previously said, there is now no reason to doubt our capability of producing all organic principles whatsoever in a similar manner. Wöhler's artificial production of urea from cyanate of ammonia in 1828, and Pelouze's artificial production of formic from hydrocyanic acid in 1831, were in reality very important pioneering achievements, although cyanogen and its compounds were at that time known only as products of the decomposition of organic bodies. But in 1845 Kolbe produced acetic acid from carbon by a series of strictly inorganic processes, and thereby laid the foundation of modern synthetic chemistry. He observed in his paper on the subject "From the foregoing observations we deduce the interesting fact that acetic acid, hitherto known only as a product of the oxidation of organic materials, can be built up by almost direct synthesis from its elements.. If we could only transform acetic acid into alcohol, and out of the latter could obtain sugar and starch, then we should be enabled to build up these common vegetable principles, by the so-called artificial method, from their most ultimate elements." Relying upon these results, Laurent in his "Methode de Chemie," 1853, and Hofmann in a course of lectures "On Organic Chemistry," delivered the same year at the Royal Institution, the latter, with very great detail, showed how impossible it was to draw the line of demarcation between carbon compounds of organic, and carbon compounds of mineral origin. They both referred to Kolbe's formation from mineral elements of acetic acid or vinegar, and of certain highly complex bodies procurable from vinegar, such as mesidine C,HN, and nitro-mesidine C,H,N2O2. It must be admitted, however, that to the labours of Berthelot, prosecuted unintermittingly for the last ten years, is due that full recognition of synthetic organic chemistry which now obtains, and the very great advances which have recently been made therein, both by himself and by others, which I propose hereafter to bring under your more especial consideration.

Before proceeding, however, to exemplify the powers of organic synthesis in the artificial formation of animal and vegetable products from carbon, hydrogen, and oxygen, I must beg leave to make a rather long digression. I propose, firstly, to bring before you some elementary experiments connected with the production and decomposition of the oxides of carbon and hydrogen, or carbonic anhydride CO2, and water H2O, respectively; and then to consider with you what bearing these experiments have upon the forces exerted in animal and vegetable life, or, in other words, upon the so-called vital forces.

I have here an ordinary form of apparatus in which hydrogen gas is being generated in the usual manner from zinc and dilute sulphuric acid, and dried by transmission through oil of vitriol. On burning the jet of dried hydrogen under this cold bell jar, we observe that the interior of the jar becomes quickly covered with a film of condensed steam or water, produced by the direct combustion of the hydrogen gas with the oxygen of the air. Now, by progerly contrived experiments, I might show you that the weight of water produced in this way is exactly equal to the weight of oxygen and hydrogen consumed in the burning. But during the combustion there is a production not only of water but of heat, which I may exhibit to you in a more striking manner. We have here a piece of clean platinum foil, which is now maintained in a state of ignition by the hydrogen flame. I turn off the supply of hydrogen for a minute or so, and before the platinum has become quite cold, turn it on again, when you observe that the metal becomes and con tinues redhot without inflaming the gas. The mixed hydrogen and air on the surface of the foil combine with one another to form water, and at the same time produce an amount of heat sufficient to maintain the metal in a state of visible ignition. But where does this heat come from? We have a production of heat and a production of

water; ought we not to account for the one as intelligibly as we can for the other?

I now take a piece of charcoal, and make it red-hot in the Bunsen gas flame. Here I have a bottle of oxygen, into which we will pour a little lime water to show the result of the action, and now that the piece of charcoal is sufficiently heated, I introduce it into the bottle of oxygen, when combination between the carbon and oxygen takes place, as you perceive, with vivid combustion. In this experiment we have, then, carbonic anhydride or di-oxide of carbon produced, the source of which is perfectly evident. Upon shaking up the clear lime water which we previously introduced, that which was soluble hydrate of calcium becomes insoluble carbonate of calcium or chalk, and accordingly we now have, as you see, a considerable white turbidity produced. If instead of absorbing the carbonic anhydride by lime water in this manner, we were directly or indirectly to weigh it, we should find that its weight was exactly equal to that of the carbon burnt, plus that of the oxygen which served to burn it. But, in addition to carbonic anhydride, there was during the combination an abundant production of light and heat. Now the axiom, that out of nothing comes nothing, is just as true of light and heat as of water and carbonic anhydride. We have no difficulty in understanding the production of the carbonic anhydride; what, however, is the origin of the light and heat?

So much, then, for the formation of oxide of hydrogen or water, and oxide of carbon or carbonic anhydride; now for their decompositions. By a variety of means we are able to separate hydrogen and carbon from their respective combinations with oxygen; one of the most convenient materials for the purpose being metallic sodium. If, for instance, we introduce under this vessel of water a piece of metallic sodium, which, for the sake of convenience, I have diluted with a little mercury, so that the reaction may take place more slowly than it otherwise would, we get, as you perceive, a regular evolution of hydrogen gas. The sodium combines with the oxygen of the water, whilst its hydrogen is set at liberty; and in a similar manner we may liberate carbon from carbonic anhydride, as I will now endeavour to show you. The carbonic anhydride produced by the combustion of a piece of charcoal in this bottle of oxygen was absorbed by means of lime, whereby we obtained a precipitate of chalk, from which by treatment with hydrochloric acid we may easily re-obtain the carbonic anhydride. Thus, if I transfer our mixture of chalk and water into this narrow cylinder standing over the mercurial trough, and then pass up a little hydrochloric acid, you observe that the chalk disappears with effervescence, while a quantity of gas collects at the top of the cylinder, which is the carbonic anhydride gas we lately produced in this bottle by the direct combination of carbon and oxygen. In the arrangement on the table before you we are producing a current of carbonic anhydride in a similar manner by acting upon chalk or, rather, marble, with dilute hydrochloric acid. The gas evolved in the Wolfe's bottle is transmitted over pumice and oil of vitriol to render it dry, and then conveyed to the bottom of an ordinary Florence flask, into which I have dropped a piece of clean metallic sodium. We now apply a large blowpipe flame to the bottom of the flask so as to heat the contained sodium. There is a little practical difficulty in starting the reaction, and perhaps the experiment may not succeed at the first trial, but it is sure to succeed sooner or later. The action is now beginning, and you observe the piece of sodium glowing in the flask. The glowing is soon succeeded by a brilliant combustion, attended by the forma tion of copious white fumes. The sodium has effected a decomposition of some of the carbonic anhydride, united with its oxygen to form soda, and liberated its carbon in the form of a black mass, which remains, as you see, at the bottom of the flask. This piece of charcoal in the flask has been extracted from carbonic anhydride gas, which is

itself producible, as I have shown you, from the direct combustion of charcoal in air or oxygen. By combining hydrogen and oxygen with one another we obtain water, and by acting upon the water with a deoxidising agent we get back the hydrogen. Similarly, by combining carbon and oxygen with one another we obtain carbonic anhy dride, and by acting upon the carbonic anhydride with the same deoxidising agent we get back the carbon, as you perceive. When we acted upon oxide of hydrogen with sodium, we separated the oxygen and obtained the hydrogen; when we acted upon oxide of carbon with sodium we separated the oxygen and obtained the carbon. Now the living plant effects a similar decomposition of these two compounds, but in a gradual manner, which we shall hereafter endeavour to imitate. The plant absorbs oxide of hydrogen or water, and oxide of carbon or carbonic anhydride, deoxidises both compounds to a more or less complete extent, evolves the separated oxygen into the atmo. sphere, and retains the united carbon and hydrogen, with or without some oxygen, in the form of vegetable tissue or secretion. When the tissue or secretion is subjected to a full red heat it. yields, among other products, free carbon, free hydrogen, and various compounds of carbon with hydrogen. The piece of wood-charcoal now in my hand, for instance, has resulted indirectly from a gradual deoxidation of carbonic anhydride by the living plant, just as this piece of charcoal in the flask has resulted directly from a violent deoxidation of carbonic anhydride by the metallic sodium.

Thus, then, we have presented to our notice the most important terrene, or rather cosmical function of plant life. The living plant effects a decomposition of carbonic anhydride and water, evolves the liberated oxygen, and retains within its organism the united carbon and hydrogen, which becoming the food of animals, are simultaneously disunited and re-oxidised once more into carbonic anhydride and water. Now, I wish to consider with you-I was going to say more minutely, but I should rather say more broadly-what is the essence of these complimentary actions in their relation to the first principles of that dynamical philosophy which is now often spoken of as the science of energetics. It formed part of my original plan to give a passing glance at this subject, but I certainly should not have ventured to discuss it in the elementary form in which I now propose to bring it under your notice, had it not recently come to my knowledge that certain principles of mechanical philosophy admitted by that class of naturalists who are called physicists to be as fundamental as the law of gravitation itself, are not generally acknowledged by that other class of naturalists who are called physicians. Now, in order to contrast with one another the great antagonistic functions of plants and animals, the decomposition of carbonic anhydride and water by the one class, and recomposition of carbonic acid and water by the other, it would not conduce to my object, even if it were within my competency, to discuss with you the simplest functions of organic life, as manifested in the most minute and simple organisms, in some of which it is scarcely possible for us to distinguish between the animal or vegetable character. Feeling that every phase of life deserves our attentive examination, I am far from insensible to the advantages attending the study of its most elementary forms. But this study cannot, I maintain, teach us the whole truth. There are principles of the highest importance which can only be learned by having regard to the directions in which animal and vegetable life respectively tend--by comparing with another the highly specialised forms of animal and vegetable life, not in their minute details, but in their broad general features. In my next lecture, then, we shall have to consider more especially what is the nature of the force exerted in the characteristic actions of vegetable and animal life-whether we have to do with some peculiar 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 world.

ACADEMY OF SCIENCES.

August 7.

M. CLOEZ Communicated a memoir entitled "Experiments and Observations on Fatty Matters of Vegetable Origin." The author's experiments were principally directed to ascertain the nature of the changes produced in drying oils by the action of air and oxygen. He first analysed various oils, and then exposed to air and light at the ordinary temperature 10 grammes of each oil in flat glass dishes lightly covered with unsized paper. The dishes were weighed every three months, to ascertain changes in weight. The whole time of exposure was eighteen months, and in this time M. Clocz found an increase of weight in every instance, but varying from 2.5 to 8.5 per cent. It is remarked, however, that the increase was not constantly progressive during the whole time. At certain times there was a diminution of weight, so that if the phenomenon was represented graphically, there would be a curve gradually rising to a certain maximum, then slowly falling to end by becoming parallel to the axis of the abscissa, but this only after a great lapse of time. The author shows that it is a simple oxidation that takes place. The amount of carbonic acid produced does not represent a quarter of the carbon that disappears. The remainder forms volatile compounds with hydrogen and oxygen, among which he proved the presence of acetic and acrylic acids, and a small quantity of anoleine. The white paper covering the dishes became brown after a time, owing to the action of the volatile compounds formed. He believes the brown colour of the leaves of old books to be owing to the slow oxidation of the oil in the printer's ink. M. Cloez gives a table of the amount of oil present in various seeds, which he determined by extracting with sulphide of carbon. This table we may give on on a future occasion.

M. Dancel presented a memoir "On the Influence of Water in the Production of Milk." The author has noticed that women, when suckling, drink a great deal more than at other times. Cows, too, before they drop a calf will be satisfied with from 12 to 20 litres of water a-day, but afterwards they require 30, 40, or 50 litres. He notices also that cows fed in houses on dry food give a fourth or even a third less milk than when at pasture. He states, too, that cows fed upon dry sesame cake gave very little milk until they were freely supplied with water. He concludes from all this that water has a good deal to do with the secretion of milk.

M. Bechamp read a paper " On Variations in the Amount of Nefrozymase present in Urine in Different States of the Body." Nefrozymase is the soluble ferment discovered by the author in healthy urine. (See CHEMICAL NEWS, vol. xi., p. 116.) The author finds that the proportion of this body is increased by violent exercise. In patients labouring under Bright's disease, and in some cases of paraplegia, it disappears altogether. In advanced diabetes the amount is somewhat increased. Other pathological states seem to influence the proportion; but the matter evidently requires further investigation before the value of the determinations can be estimated. The author states the urine of men contains more than that of women; and in every case the urine of the blood-that is to say, that secreted at nightcontains the most. M. Bechamp also states that albumen may be passed in the urine in two forms-one coagulable by heat and alcohol, and then remaining insoluble in water; the other, not coagulable by heat, but precipitated by alcohol and soluble after precipitation. This soluble albumen differs from nefrozymase by having no action on starch paste, which, our readers will remember, is liquefied and changed into glucose by nefrozymase.

NOTICES OF BOOKS.

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. WE cannot say that we are struck by either Dr. Wood's matter or style, or, indeed, anything that is exclusively his, though we of course share his opinion that it is extremely desirable that, at all events, the elements of a science which receives more practical applications in everyday life than any other should form a part of every boy's and even girl's education.

Dr. Wood very correctly remarks that school is the place where the foundation of a scientific training must be laid, and for this reason advocates early instruction in chemistry. "The real use," (he says in another place) "and value of chemistry to boys as compared with other subjects of education is a matter of opinion, though it is of great importance at the present time, especially on account of the Government inquiries into matters of education."

We may here leave Dr. Wood to give some of the results of the Government inquiries. The Select Committee of the House of Lords on the Public Schools Bill put the three following questions to Professors Huxley and Tyndall; Dr. W. A. Miller, and Dr. W. Sharpey-viz. :Question 1.-"In what branches of physical science should instruction be given in our public schools, and what branches, if any, should be excluded?"

Question 2.-"In what manner should that instruction be imparted; should there be periodical examinations of the pupils, and prizes for proficiency; and by whom should such examinations be conducted, and such prizes awarded?

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Question 3.-"Should instruction in science be made imperative by positive enactment, and if not, in what mode should it be promoted and encouraged by the Legislature?"

In answer to the first question Professor Huxley states that he is strongly in favour of confining instruction in science for disciplinal purposes to elementary physics (with incidental chemistry) and botany, with the addition of the outlines of human physiology. A boy well grounded in the rudiments of these sciences would find none of the methods and very few of the conceptions of the others absolutely strange.

In reply to the second the Professor says that the most perfect method of teaching science is that pursued by anatomists, and chemists, who combine lectures with prac tical demonstrations, and he very properly insists that University rewards should be open to boys who show special aptitude for scientific research.

Dr. Tyndall is no less explicit in his answers. He contends that instruction should be given in elementary physics, comprising under this term the phenomena and laws of gravity, light, heat, sound, electricity, magnetism, and the mechanical properties of air and water.

The first principles of chemistry ought also to be taught in our public schools.

Instruction in these subjects should, in his opinion, be rendered imperative.

He too advocates lectures and demonstrations, but does not at present recommend laboratories and practical instruction.

Dr. Miller's replies we give at length:-

"Answer to Question 1.-I consider that instruction should be given in Mechanics, including the principle of the composition and resolution of forces-centre of gravity, the mechanical powers, the laws of motion.

"2nd. Hydrostatics and Pneumatics, including the principle of fluid pressure, specific gravity, construction of the barometer, the air pump, common pump, and forcing pump: the siphon.

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

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