In the eleventh section we have an account of the manner of ftaining wood, ivory, bone, horn, hair, marble, agate, &c. black. This part is concluded with the following curious experiment:- Pieces of different ftones, marbles, pebbles, flint, &c. were washed over with a faturated folution of copper made in aqua-fortis: when dry they were put into a crucible, and kept for a little time in a fire just fufficient to make the veffel almost red-hot. All of them were stained, in the parts which had been moistened by the folution, of a black colour, durable and pretty deep, though it had penetrated only a very little way into the fubitance of the ftones.

ance.

• When the smooth surface of an agate, or other stones nót diffolvable in aqua-fortis, is moistened with a copper folution; if a small iron nail be fet upright on its head in the middle, the iron absorbs the acid from the copper, and the copper, now feparating from the fluid, fhoots into fine ramifications like the branches of trees or fhrubs, generally of a very elegant appearIf the nail be then removed, and the corroded iron carefully washed off by dipping the ftone in water, the vegetations may be changed by heat to the fame black colour as the fimple folution of copper in the foregoing experiments, fo as greatly to refemble the figures naturally found in certain ftones, as that called the mocho-stone. The colour is not indeed fixed on the stone, like that refulting from the solution of copper alone; but a plate of crystal laid over it in the manner of a doublet, conceals the imperfection. The only difficulty in this operation confifts in the washing, in which great dexterity is requifite, to feparate the corroded iron, which would give a rufty ftain, without wafhing off or difordering the fine vegetations of the copper.'

With the twelfth fection, which treats of black glass and enamel, Dr. Lewis finishes the first part of his history of colours. The experiments and inquiries, which make up the remainder of this volume, are folely employed upon the Platina, of which indeed we have a very full hiftory, extended to the length of 169 pages. For this, however, we must refer our Readers to the work itfelf, as the abftracts and quotations already made have fwelled this article to a very confiderable bulk.

The Appendix, which is added to this volume, contains fuch obfervations and improvements, as occurred to our Author, after the former parts of the work were printed.-Dr. Lewis, when giving an account of the effects of the mineral alcali on platina, refers to the appendix, he

this alkali from fea-falt.-Pure rects a process for obtaining

fea-falt is compofed of the neral alkali and the marine acid; if you detach this marine acid by the addition of acid of nitre, or, as it is commonly called, fpirit of nitre, you then obtain cubic nitre, which is a neutral falt formed by the union of the acid of nitre with the mineral

alkali :

alkali and from this compound the mineral alkali is eafily procured in a feparate ftate, by deflagration. In order that this procefs may fucceed, it is neceflary that the fea-falt be pure, confifting only of its acid and the proper alkaline bafis. The general admixtures with fea-falt Dr. Lewis enumerates, and the methods of getting clear from thefe. He then gives directions for obtaining the cubic nitre.

6 Mr. Marggraff, fays he, in a differtation on the best method of feparating the alkaline fubftance of common falt, found that two parts of fmoking spirit of nitre, of such strength as inftantly to fire pure oil of cloves, were fufficient for one part of purified common falt; but of the weaker nitrous fpirit, called aquafortis, he recommends eight times the weight of the falt. He fays the cryftals obtained with the smoking spirit (for he does not feem to have tried the weaker one) were pure cubic nitre, which deflagrated on a burning coal without crackling, and had not the leaft mixture of common falt. Some have reported, that though a pretty ftrong fpirit of nitre was ufed in more than double the weight of the falt, the refiduum after the diftillation confifted chiefly of marine falt unchanged, with only a small pro.. portion of cubic nitre intermixed *. On what cause the failure depended, the few experiments I have made on this head do not enable me to judge: perhaps it may be neceffary that the nitrous fpirit fhould be very ftrong, for a concenterated acid may produce decompofitions, as well as diffolutions, which the fame acid, diluted, is incapable of effecting.'

The marine alkali being, by the above methods, combined with the nitrous acid, the acid is to be separated from it by deflagration with inflammable fubftances. Mix the cubic nitre with one fifth, or one fixth of its weight of powdered charcoal, grinding them thoroughly together: the coal of animal fubstances is preferable to that of vegetables, as the latter will leave, after burning, fome fmall portion of an alkaline falt, of a different nature from that which is here required. Throw the mixture, by a very little at a time, into a large crucible made just

The caufe of the failure here mentioned by Dr. Lewis we apprehend to be this; in the diftillation of the acid of fea-falt by means of the addition of the acid of nitre, this laft is fo volatile as to come over in a confiderable proportion into the receiver, together with the acid of fea falt which it had detached: and the quantity of cubic nitre which is produced muft neceffarily be only in proportion to the quantity of acid of nitre which remains in the retort, and is united with the alkaline falt. -To remedy this inconvenience, nothing more is requifite, than frequently to repeat the diftillation with the addition of fresh acid of nitre. Thus the fea-falt will be effectually decompofed, the alkali will be perfectly faturated with the acid of nitre, and nothing will remain in the retort but a pure cubic nitre.

U 4

red-ho",

red-hot, covering the crucible, as fpeedily and as close as may be, after each injection, to prevent the matter from being diffipated by the ftrong deflagration which enfues. When the mixture has been all thrown in, and the detonation has ceafed, the fire may be augmented, and a pretty ftrong red heat kept up for half an hour or more, the crucible during this time being left uncovered. The nitrous acid being thus burnt out, there remains in the crucible a bluish-greenifh alkaline mafs, which is to be purified by folution in diftilled water. It diffolves more difficultly than the vegetable alkalies, and, on duly evaporating the folution, fhoots into fine white cryftals, which do not liquify in the air.'

The original of this procefs was firft given by Mr. Boyle; was adopted by the fucceeding chemists; and is here fully and accurately delivered by Dr. Lewis.-There is a method likewife of obtaining this mineral alkali from another of the native neutral falts.If Glauber's falt, which is a compound of the vitriolic acid and the mineral alkali, be fufed with fome powdered charcoal, the vitriolic acid unites with the inflammable principle of the charcoal, and forms common fulphur, at the fame time the alkali is joined with this fulphur and produces an hepar fulphuris; from this again the alkali may be difengaged by means of an acid: if we add the nitrous acid, a cubic nitre is produced, which may be treated according to the foregoing procefs: if a vegetable acid be employed, the alkali of the hepar fulphuris forms with this a neutral falt, called the polychreftum rupellenfe: in this falt the union of the acid and alkali is fo weak, that it may be cafily diffolved by the action of the fire; a proper calcination therefore diffipates the acid, and leaves the alcali in its pure ftate.

Dr. Lewis has thus brought to a conclufion the first volume of his Philofophical Commerce of Arts, in which he has been very full upon the following heads: I. The defcription of a portable furnace for making experiments. II. The hiftory of gold, and the various arts and bufineffes depending thereon. III. Experiments of the converfion of glafs veffels into porcelain, and for eftablifhing the principles of the art. IV. Of the expanfion or contraction of certain bodies at the time of their paffing from a fluid to a solid ftate. V. Of the blowing air into furnaces by a fall of water. VI. The hiftory of colours; Part I. of black colours. VII. The hiftory of platina.

We are forry to obferve, from a paffage in our Author's preface, that the further profecution of this valuable work may now probably be dropt. How far, fays he, thefe principles and thefe views have a juft foundation, or may tend to the advanceinent of arts and useful knowledge, and whether this laborious

and

and expenfive undertaking fhall be dropt or profecuted, is left to the determination of the public."

When we confider the application, labour, and expence, which must attend the execution of fo great a defign; we almoft wonder that any thing less than a SOCIETY, of able, industrious, experienced, and philofophical chemists, should have been hardy enough to enter into fo wide a field. Such a work, however, we fee, has been planned, entered upon, and in part executed, by an INDIVIDUAL: executed too in fuch a manner, as to be at once entertaining, interefting, and very extenfively useful: for Dr. Lewis not only relates his own experiments and obfervations, together with the common practices in the respective arts, but refers likewife to fuch improvements as have been made by the best authors who have turned their chemical inquiries towards thefe fubjects.As the continuance therefore of that amazing power and grandeur, to which this nation has arrived, ftrictly and neceffarily depends upon the perfection, vigour, and extent of our arts, manufactures, and commerce; we trust that the Author of the Commercium Philofophico-Technicum, will not be left, UNENCOURAGED, UNPATRONIZED.

D.

Twenty-two Sermons on the following Subjects: The Explication and Proof of the Divine Goodness.-The Goodness of God illuftrated in Creation, particularly in the Frame of Man, in Providence, and Redemption. The principal Properties of the Divine Goodness.The Objections drawn from moral and natural Evil, and future Punifhments, anfwered.-The Evidences of a future State.-The Neceffity of Holiness.-The proper Temper for enquiring after eternal Life, and Jefus Chrift the best Guide to it. By Thomas Amory. 8vo. 6s. bound. Becket and De Hondt.

A

S the belief of a Deity is the foundation of all religion, juft and honourable fentiments concerning the Deity are, confequently, of the utmoft importance in every inquiry wherein religion is concerned. GOODNESS, in particular, is that perfection of the Divine nature, of which, above all others, it moft concerns us, to have just conceptions, and fatisfactory evidence. Without the belief of the divine goodnefs, indeed, there can be no true religion, and the universe must appear a dark, uncomfortable wafte. Neceflary existence, eternity, independence, immenfity, unerring wifdom, and confummate rectitude, can only fill the mind with awe and admiration: it is GOODNESS alone that can excite love and reverence. When this glorious attribute is added to the other perfections of Deity,

Deity, the face of nature affumes a bright and chearful aspect, omnipotence is difarmed of all its terrors, the awful splendors of eternity and independence are foftened into the milder glories of kindness and condefcenfion; the tribunal of impartial justice becomes the feat of mercy; the mind of man is reconciled to all events; his heart is filled with joy and confidence; and he can look up to the dread fovereign of the universe as to a kind and gracious Father.

There cannot therefore be a more important or a more delightful fubject of enquiry than that of the goodness of God; and to the unspeakable comfort of every rational being, there is no truth of which there is clearer evidence. The traces of the divine power are not more striking or more numerous than those of his bounty; nor is any thing wanting in order to be convinced of this, but due attention and confideration.

The fubject has been often treated by many able writers; but the beft of thefe, as the judicious Author of the difcourfes now before us obferves in his preface, have aimed more at the fatiffaction of the thoughtful and ftudious, than the instruction and conviction of the main body of Chriftians, who yet are equally interested in this important doctrine.

They have alfo omitted, continues he, a diftinct and animating reprefentation of the practical confequences. The author of the following difcourfes hath therefore endeavoured to fet the evidences of this great doctrine in a light easy to the underftandings of the generality, ftill preferving their clearness and ftrength; and to affift perfons in regarding the works of God in a view, proper to raise their apprehenfions of the divine good.. nefs, and to warm their hearts with an habitual sense of it, and engage them to live as always furrounded with the prefence and kindness of the beft of Parents, well affected to their brethren, alike children of the great Father of Spirits, chearfully refigned amidst the trials of life, and ferene and full of hope at death.

This the Author can fay, that to the firm belief, and frequent meditation of thofe interefting truths, which are included. in the boundless benevolence of our Creator and Governor, he himself hath been obliged for the most valuable fatisfaction he hath known in life; and to these he owes it, that he can look forward to a future ftate with the nobleft hopes. And if the publication of the following difcourfes fhall make these truths more cordially received, and their beneficial interest more felt, he shall greatly rejoice in the time and thought employed for these purpofes.'

As Mr. Amory has purfued the main fubject of his fermons thro' feveral difcourfes, and proved and illuftrated the great doctrine of the divine goodnefs from a variety of important topics, a regular abftract of what he has advanced cannot be expected from