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1851.

Dawn of Modern Chemistry.

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speculative philosophers, it owes much; and very much also, to the experimental researches of Wollaston and Thomson. But the analytical labours of Berzelius, which were devoted for so many years to the determination of what are called Atomic weights or combining proportionals, and the investigations of Gay Lussac on the combining volumes of gases and vapours, contributed more to the rational establishment of this new system than those of any other individual chemists. Many cooperated, however, in different degrees; and a valuable sketch of its progress, and of the shares of the several fellow-labourers, will be found in an able treatise On the Atomic Theory,' by Dr. Daubeny, of which a second edition has recently appeared from the Oxford press.

The multiplied analytical researches of Berzelius may be said to have given rise also to the now most recondite and difficult department of analytical chemistry. The knowledge bearing upon the inorganic, —so refined and abstruse a portion of this department, — has been extended and enlarged by several of his pupils, and especially by Professor Heinrich Rose, of Berlin. It might have been supposed to have been digested and matured in the Ausführliches Handbuch der Analytischen Chemie ' of this distinguished analyst. For Professor Rose's • Manual' is a book of 2000 octavo pages; and yet, like nearly all our chemical books, it was already behind the time before the last sheet issued from the press.

These analyses led successively to the discovery in Sweden, and elsewhere, of many new elementary bodies. By a simple or elementary body chemists mean one which is incapable by any known methods of being resolved into two or more other bodies differing from itself. Compound bodies again consist of, and can by known means be resolved into, two or more elements regarded as simple. Of such elementary bodies only twenty-nine were known at the beginning of the present century; we are now acquainted with sixty-three. This fact will illustrate to the general reader one great feature in the progress of modern chemistry. But to the chemist the discovery of thirty-four new elementary bodies implies an amount of painful research, - preceding and following each discovery, -- of which words can convey to the uninitiated no adequate idea.

It is not merely that the satisfactory isolation of a new element is itself a work of long and discriminating labour, or that it imposes almost endless after-inquiries concerning its relations and combinations with other bodies; but such a discovery casts a doubt upon all past analyses of a particular class, and renders imperative a repetition of many most serious investigations. The way in which each analytical discovery thus throws us back, as it were, will appear by a simple illustration. It was early discovered that the mineral matter of plants contained silica - the substance of flint- in considerable quantity. Yet, this substance was supposed to form no part of the bodies of animals, and to be a characteristic feature of the vegetable kingdom, till an analysis of the feathers of birds proved that they too contained silica in a very sensible proportion. It was sought for, therefore, in the natural covering, - the hair of animals and man; and new analyses proved it to be present there also. But if in the hair it must be in the blood, from which all the parts of the body are formed and draw their constant support. Renewed examinations of the blood, accordingly, discovered it there, and thus new light was thrown upon animal physiology, and upon the natural relations between plants and animals.

So also in nearly all our analyses of the ashes of plants and of the parts of animals, common salt had been found in comparatively small proportion. But recent research, conducted after improved methods, has shown that some at least of these ashes contain this substance in much larger proportion than was previously believed; they, therefore, suggest the necessity of repeating all our experiments in this field before the true composition of the inorganic part of living beings can be said to be ascertained. Iodine, in like manner, early found in marine plants, has recently been detected in the common cress, and in many other plants which grow in fresh water. Must we not expect to find it in all plants? Is its presence not necessary to the healthy sustenance of animals ? Fluorine exists in sea-water and in marine plants. But it exists also in the bones and teeth of all animals, in milk and in blood. It must therefore be present in all vegetable food, and must be necessary to the healthy growth both of plants and animals. In the past analyses, however, of the mineral matter of the plants on which we live, it has neither been sought for nor detected. The same imperfect process of preparing the ash of plants and animals, which has caused a portion of the common salt to disappear, has probably also lessened the true amount both of iodine and of fluorine in the specimens hitherto analysed. Even bromine may possibly not be absent from plants and animals, if carefully sought for. Those who are aware of the amount of analytical labour which during the last ten years bas been expended upon this branch of analysis, chiefly for the benefit of agriculture and physiology, will be able to estimate the nature of the task which awaits the chemist, by whom it must all be repeated. In this way new discoveries in chemistry are continually harking us back. Old analyses in the inorganic kingdom,

1851.

Relations of Chemistry to Mineralogy.

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though useful to a certain extent, all become from time to time un-trustworthy, and the labours of years must be gone over again. But this is only the periodical retiring of the monthly wave, which at the next spring-tide may assert a wider and more secure dominion than it ever possessed before.

It is in connexion with mineralogy that the inorganic chemistry of our time finds one of its most indisputable triumphs, the atomic theory one of its most interesting applications, and chemical analysis the field of its most arduous and constantly renewing tasks. Born in a country rich in minerals, and abounding in mineral wealth, Berzelius and most of his chemical pupils and successors in Sweden have dedicated much of their attention to the productions of the mineral kingdom. Before him Klaproth and others had analysed many of these substances, without knowing or even thinking of any general principle, by which either the results of their analyses might be tested, or the minerals themselves classified and arranged.

It was after his visit to England in 1812 that Berzelius threw into a methodical form the results of his numerous mineral analyses, and applied to them the new views in respect to the electro-chemical relations of bodies, and the proportions in which they combine with each other. In 1814 the Swedish edition of his • Application of Chemical Proportions to Mine• ralogy' was published. Within a few years it was known and reprinted in most European languages. Its illustrations were subsequently from time to time augmented, and the principles on which it was based more firmly fixed, by numerous fresh analyses executed by himself and others. The most complete form in which his latest views have yet appeared is in the · Berzelius's

Neues Chemisches Mineral System of Professor Rammelsberg of Berlin, published in 1847; while the book which at present most fully represents the actual condition of chemical mineralogy is the · Handwörterbuch der Chemischen Theils der . Mineralogie' of the same author, with its four several supplements.

To those who are capable of contrasting the old mineralogy with the new, the happy conclusions, which the numerous analytical labours of Berzelius and his pupils have successively attained in this branch of science, appear very striking. What

This work presents another instance of the rapidity of chemical progress. It was published in Berlin in 1841, and contains 768 pages. The last of the four supplements appeared in 1849, and they contain in all 762 pages. The new matter of the last eight years is equal in bulk to all that was known before !

was formerly an undigested collection of rude stones, brought together according to no natural law, and arranged only according to weight, colour, hardness, or form, more or less imperfectly determined, analytical chemistry has classified into families and groups, beautifully scientific, and characterised by singular analogies in form and composition. It has established close relations among individuals and classes, such as could not previously be even suspected to exist. It has afforded to the philosophical generaliser the means of testing the correctness of analyses, of determining what is essential or otherwise to the composition of a mineral, and of thus assigning to it its proper place in his groups and system. And re-acting, as all such special investigations do, upon pure chemistry, the development of this branch — uniting in itself the joint investigation of composition and of crystalline form — has made known the existence of analogies and relations among long familiar elementary bodies, of which the study of merely artificial combinations had previously given us no intimation. It has been recognised, in short, that the interior of the earth is nature's laboratory, in which she is continually carrying on an endless variety of chemical operations, the results of which, like those which are obtained in our own laboratories, belong altogether to the domain, and are subjected to the recognised laws, of chemical science. Mineralogy, in so far as it is not purely physical, is, in fact, only a subordinate branch of inorganic chemistry. Pure minerals must be arranged, like all other pure chemical combinations, and like them are capable of being represented by definite literal formulæ.

No one who has not himself been for some time occupied with mineral analysis can have any idea of the world of time and labour which has been spent in the analytical investigation of mineral compounds. Among the thousands of specimens which adorn our cabinets, one beautiful group, long distinguished by the name of zeolites - hydrated silicates of alumina, with lime, potash, and soda, chemists now call them - is well known to mineralogists. The drawers now before us contain about fifty species belonging to this group. We take up at random a specimen of Laumonite, named from its discoverer, Gillet de Laumont. This mineral has been analysed successively by Vogel, Gmelin, Dufrenoy, Connel, Von Babo, Delffs, Domeyko, Malaguti

, and Durocher. Nine analytical chemists have each, at successive periods, with a knowledge of the labours

their predecessors, devoted some weeks to the examination of this one stone; and yet its chemical formula and most natural relations are still open to question. On a moderate calculation,

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Use of the Blowpipe in Chemistry.

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an amount of chemical activity equal to that of four long and laborious analytical lives, has been expended in elucidating the composition of these zeolitic minerals alone. How long must it be before a reasonable man can expect chemical mineralogy to arrive at its final settlement !

Our space admits only of an allusion to the beautiful researches into the relation of chemical composition to crystalline form in natural and artificial compounds, which have given Mitscherlich a distinguished place in the conjoined history of chemistry and mineralogy. Isomorphism, Dimorphism, Isodimorphism, and the doctrine of Replacement, are all subjects suggestive to any one well read in the history of chemical progress, of many successive labours; of memoirs and experiments full of beauty; and of numerous partial but gradually widening generalisations. But in this branch, as in the direct analyses of our zeolitic minerals, a single page of a systematic treatise' comprehends often the results of whole lives of thought and toil. The young student, as he masters the page before him, acquires the knowledge of grey-haired philosophers in the maturity of their fame and fortune. Yet he can never look upon his learning with the interest which those men feel who are familiar with the difficult passages and hard struggles through which the fame has been achieved, or the knowledge arrived at, which the page embodies.

Before quitting this topic, however, we must spare a few words for that subtle, almost microscopic, branch of qualitative analysis, where the blowpipe is made an instrument of research in mineralogy and inorganic chemistry. To Berzelius the world owes the first treatise which brought the blowpipe into general use among chemists. His volume On the Use of the * Blowpipe in Chemistry and Mineralogy'* appeared in Swedish in 1820, and contained the results of many years' experience of his own, added to the earlier knowledge he had acquired from the personal instructions of Gahn. Among the men of whom Berzelius always retained an affectionate and grateful remembrance, was Assessor Gottlieb Gahn. Already advanced in years, but full of the mineralogical knowledge of his time, and skilled above every other Swede in the employment of the blowpipe in chemical inquiry, he encouraged by his kindly notice and sympathy the rising chemist, while still struggling with early difficulties. He communicated to him, also, all the

Om Blåsrörets Användande i Kemien och Mineralogien. Stockholm, 1820. It was translated into German, French, English, Italian, and Russian.

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