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pass; who owneth no particular home, and who is of a steady mind. They who seek this amrečtă of religion even as I have Said, and serve me faithfully before all others, are, moreover, my dearest friends.'
The three next Lectures contain an explanation of Eastern terms, of which we can give no analysis.—The sixteenth is on good and evil destinies, ;--the seventeeth on Faith divided into three Species ;--and the last, on forfaking the Fruits of Action for obtaining eternal Salvation.
We have given the most comprehensive account in our power of this very curious work; but, while we own that it must be necessarily inadequate, we hope it will excite the curiosity of our readers to peruse a work, supposed to be written near eight hundred years before the time of Mofes.
A Disertation on Elective Aitractions. By Torbern Bergmann. Translated from the Latin. 8vo. 6s. in Boards. Murray.
we may, without incurring the charge of rashness or precipitation, trace the rapid progress of chemistry from the period in which tables of elective attractions were first formed. From the time of Geoffroy, our labours have been more pointed and accurate, our conclusions more clear and decisive, and chemical knowledge, in general, more improved than in the long series of ages which preceded. Some of these additions, to our knowlege, may undoubtedly be attributed to the spirited investigations of an enlightened age, to the liberal mode in which enquiries are now carried on, and to the number of labourers in the field of science ; but it will be at once obvious that to ascertain what has been done, and where our experience is deficient, is the firt method of directing enquiries to the best purpose, and of preventing others from wafting their time on what is already known. M. Geoffroy, therefore, who published the first Table of Affinities in 1718, has gained by it the highest reputation, though the table itself was short, imperfect, and indecisive. It was, however, the first attempt, and the fame which he acquired has been in a great degree supported by his other works. In the age of Geoffroy, soon after his first publication, an obfcure chemist in Germany, M. Grosse, improved and added to his list. He read, he ftudied, and made experiments in filence and obscurity : at his window he delighted to puzzle the passengers; but never would explain any thing till he had completely astonished them. This table was privately copied, and never published till 1748. We have given these particulars to rescue his name from oblivion, and to inform the world of the peculiarities of its instructor, He introduced a geometrical method of argu
ing; for instance, nitrated mercury, sea-falt, and vitriol, being given, what will be the result of diftilling them together? This method exercised his pupils in the use of his table, but has introduced too much reasoning in a science which chiefly rests on experiment. Soon after this time, a Night attempt in the fame way was published in the early editions of Quincy's Difpenfatory.
In the year 1750, Mr. Gellert, a Saxon chemist, published a table with confiderable additions ; but he entirely changed the order of the substances; for that which had the least relation to the body at the head, stood in the first rank. His work was translated into French, in 1758; and Mr. Spielman adopted his table, in his Institutes of Chemistry, published in 1763. There are many errors in it, particularly respecting the effect of heat on the earthy bodies. It contained twenty-eight columns.
In 1736, M. Rüdiger published, at Leipfic, a Table of Afo finities, in fifteen columns; to which were added, ten columns of substances which would not unite without preparation. This was a very useful addition : the explanations are in Ger. man; but this work is not valuable, on account of the irregularity of the order, and the few substances inserted in each column.
Another Table was published by M. Limbourg, in 1758. It is very full ; but erroneous and imperfect. In 1.763, that part of the famous Encyclopædia which relates to chemistry appeared, and in it a new Table, which has never been attributed to any author. It is chiefly composed from those of Geoffroy, and the almost forgotten Groffe, and is full of imperfections as well as contradictions. The new edition now publishing was, therefore, much wanted. Soon after this time, for our history has led us so far, that we must hasten to a conclusion, Dr. Black, in his class, gave an improvement of Geoffroy. Many new columns were added, and different subftances subjoined to the old ones, with more discriminating exactness. It was, at that period, the most perfect table that had appeared. In 1769, M. Machy read, at the Royal Academy, an explanation of his new table, which poffeffes great merit: and, in 1775, the Dissertation of Bergmann, which has occafioned this detail, was published in the new volume of the Upsal Transactions.--Let us finith our history, in the words of the very intelligent translator.
Since the above, besides many alterations which totally change the disposition of it, not less than nine new columns have been added, which, if all the rectangles were filled up, make 9 x 50 = 450 new rectangles. I have no doubt but that
an equal or a greater number of additions will hereafter be made in an equal number of years. Even since the publication of the third volume of the Opufcula, in 1783, two, or perhaps three substances have been discovered which will claim a place on the Table of Elective Attractions; these are what Mr. Scheele considers, as the acid inherent in tungstein, or lapis ponderosus, the metal which Messrs. Luyart obtained from tungfein ; for wolfram only differs from it in being combined with iron and manganese, and the acid of the filk-worm, and some other infects, described, by M. Chaussier, in the Dijon Me. moires for 1783."
We have investigated this history with some attention, be. cause we think it of great consequence. Since the first Efay of M. Geoffroy, though many have been the attempts to improve his Table, the success has not been proportional. Besides, the number of candidates who have contended with him for fame, has not been equal to those authors who have transcribed his arrangement, with little addition. Each of thefe have, till within these ten or fifteen years, joined in his praises. About that time so many exceptions seemed to occur to every attempt of this kind, that the best chemists began to relax in their efforts, despairing of bringing it to perfection. In fact, they employed substances as simple bodies, which were really compounds; and they varied their experiments without being aware of, or allowing for, the variety. Confufion consequently succeeded to order, and each general rule was clogged with exceptions so numerous, that it lost its use. The discovery of the aerial acid began to lead chemists into a clearer light; and, by following this clue, Bergmann, in the work before us, has elucidated many difficulties, and reconciled many apparent contradictions.
Excess of heat is one cause of the feeeming exceptions; and irregularities arise, as we have hinted, from double attraction. We shall infcrt a short specimen of our author's reasoning on this subject.
• Chemists, in determining the single elective attractions, are often deceived by double attractions. The phosphoric acid, as I shall hereafter thew, attracts lime more powerfully than fixed alkali; yet the contrary is asserted, since aerated alkali, by means of a double affinity, precipitates phosphorated lime: Even caustic fixed alkali, which seems a stronger proof, causes a precipitation : nevertheless, if the superior attraction is des duced from this alone, the conclufion will be erroneous; for the alkali only takes away the excess of acid which is requisite for folution, and hence the phosphorated lime falls to the bottom. The difference between the action of alkalis and absorb. ent earths, when saturated with accial acid, and when deftitute
of it, has been explained in my effay on that acid, and may, therefore, be omitted here. It may now, in general, be obferved, that alkaline and earthy substances are to be considered as doable, and by no means as simple salts, except in their cauftic ftate, and then I call them purea
• The precipitation of metals, diffolved in acids, by other metals, is never the effect of single attraction ; for during the solution, a quantity of phlogiston is extricated, as I have clearly, I hope, shewn elsewhere. Since, therefore, metallic folutions are of such a nature, that they cannot restore what they hold. dissolved to 'its metallic splendoar without the accession of a new portion of phlogiston, it is felf-evident, as well as conformable to experiment, that this cannot be effected by the addition of calces. If, therefore, cchre be put into a solution of vitriol of copper, no copper will be precipitated; but iron added to the solution is foon observed to be covered with a cupreous pellicle; for it yields part of its phlogiston, which is necessary to the reduction of the copper, and by this means becomes itself soluble without the emission of any inflammable air. Silver diffolved in the nitroos acid, is in like manner calcined; as appears from the red vapour, phlogistic fmell, and various other evident figns, and therefore cannot be precipitated by the calx, though it may by regulus of copper. The fame obfervation is applicable to gold and the other metals ; for in whatever way they be separated, provided they can acquire no phlogiston, they appear calcined, and really are fo: the only difference confifts in this, that they are unequally dephlogisticated, and that the noble metals can recover their loss by fusion alone in ignited vessels, whereas the ignoble ones require an addition of phlogiston.'
Exceptions which have been made, are also sometimes owing to a successive change of substances; as, for instance, the nitrous acid is phlogisticated by adding marine acid, and then adheres so loosely to an alkali as to be dislodged by any acid, Nitre, kept some time ignited, in the same way may be separated even by vinegar; but the order in which a compound body is arranged, ought not to form an exception to the af. finity of the body, when simple. When a subitance separated is soluble in the menftruum, or when the solution is capable of dissolving the disunited body, we also see an apparent, instead of a real irregularity. The same occurs when the subftance, which we expect to fee separate, is capable of uniting to the new compound, or when a determinate excess of any of the ingredients is required to form the body, in a state fit for separation ; as of an acid in crude tartar, and of an alkali in borax. All these circumstances have perplexed the practical chemists; and Bergmann's explanations, which cannot be expressed in Norter language than his own, are curious and instructive.
He then examines each column in his Table, and explains in general, the nature of the substance at the head, and the experiments on which the subsequent order is founded. He tells us also, where they are arranged from analogy, and when from conjecture : these difficulties must be removed by future experiments. Of a work so miscellaneous, we can give no regular analysis; and shall extract only a short passage, which contains information not generally known, viz. on the colouring matter of Prussian blue.
• I have long conjectured, not without reason, that the tinging matter in Prullian blue is of an acid nature, as it forms compounds of an intermediate kind with alkaline salts, as well as with earths and metals. Mr. Scheele has lately taught us how to separate the acid in a pure state. Phlogisticated alkali, as it is commonly called, is a triple falt; containing the ting. ing acid, saturated partly with iron, and partly with alkali, This salt, boiled in a retort with weak vitriolic acid, emits the tinging acid in an inflammable aerial form, which may be abforbed by water placed in the receiver. And as at the same time, fome vitriolic acid pafles into the receiver, the liquor Thould be again distilled with a little chalk, till one-fourth fhall have passed over ; which is a solution of the present acid in water. The following process answers the same end with less trouble : let Sixteen parts of Prussian blue be boiled in a concurbit, with eight of mercury, calcined by means of nitrous acid, and forty-eight of water, for a few minutes, with conftant agitation. The mixture becomes of a cineritious yellow; it should be put on the filter, and the residuum elixated with boiling water. To the filtered liquor, let twelve parts of pure iron filings. be added, and three of concentrated vitriolic acid, After a Thaking of some minutes, the whole mass is turned black by the reduced mercury. After the fubfidence of the powder, the clear liquor is to be decanted into a retort, and one-fourth abstracted.'
A commentary on a table of elective attractions must contain an abstract of the whole science; and the abstract before us is not only full and comprehensive, but clear' and satisfactory, New discoveries must, however, have affected many parts of the work; and some mistakes, the errors of humanity, may be occasionally observed. Many of these are corrected by the translator, who, besides adding some valuable notes, has executed his talk with great skill and judgment. He appears to be of opinion, that the late discoveries relative to the naturę of water, by Mr. Cavendish and Mr. Watt, are fully established; but we still entertain some doubts. If they are once exactly ascertained, we agree with him in thinking that they will have an extensive in uence over every branch of chemical