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to fome wild beaft. However, they usually stuff a large bundle of brush-wood, or bushes, into the aperture of this hole or paffage.

• I was very affiduous in my enquiries, in how far it was true, that the Hottentots fecluded from fociety fuch as were old and helpless. The only perfon that could give me any inftance of this cuftom being practifed, was my hoft. In his younger days, being out a hunting in Krakekamma, in company with one Vander Wat, with whom I was likewife acquainted, they obferved in the extenfive defert plains of that district, a little narrow flip enclosed with bufhes and brambles. Their curiofity being excited, they rode up to it, and found within it an old blind female Hottentot, who, at first, as soon as she heard the Chriftians coming, endeavoured to crawl away and hide herfelf; but afterwards made her appearance, though with a very four afpect: fhe confeffed, however, that fhe had been left to her fate by the inhabitants of her clan. But neither did fhe defire nor receive any affiftance from thefe Chriftians, nor, indeed, had they made any enquiries whether this was done with or against her confent.

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Calling afterwards at the craal fhe belonged to, all the information they got there was, that the old woman had actually been left there in that manner by them. With respect to any conveniencies fhe might have about her, they could perceive nothing, but a trough which contained a little water.

Another custom, no lefs horrid, which has hitherto been remarked by no one, but which I had fully confirmed to me, is, that the Hottentots are accustomed to inter, in cafe of the mother's death, children at the breaft alive. That very year, and on the very spot, where I then dwelt, juft before my arrival, there had been an inftance of it.'

On the vegetable kingdom we do not find much information befides what we have already mentioned. The Hottentots are acquainted with the nutritious quality of the gum arab. and the plant from which it is produced, the mimofa nilotica, is frequently found in the fouthern parts of Africa. We think it might be made a valuable article of commerce, if the Dutch would enlarge their fyftem, and, by extend ing the knowlege of this coaft, extend also its advantages. So jealous are they of their fituation, that they conceal the numerous harbours in the fouthern extremity of the world, by the most narrow and injudicious policy. Every thing is ordered to be conveyed by land, and the only animals employed in drawing their waggons are oxen. This is not only a confiderable impediment to the increase of their colony, but to the trade of the Cape: the inhabitants are fupplied with neceffaries at a greater price; and the goods bought, to carry away on their return, are few and trifling. We ought

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to have mentioned, that there is a kind of aloes prepared in this country lighter than the fuccotrine, but feemingly not of fuperior value. Dr. Sparrman relates the method of preparing it,

We must now leave our inftructive author, not without thanks to the able tranflator, for his valuable addition to the ftock of English literature. We have received much pleasure and information from the perufal, which we could not communicate; and we muft neceffarily refer our readers to the volumes themselves for farther information, which is very plentifully interfperfed among the incidents recorded in a lively and fpirited journal.

Thoughts on the Properties and Formation of the different Kinds of Air. 8vo. 5s. in Boards. Murray.

THERE is fome novelty and ingenuity in these Thoughts;

but they are much obfcured by an unphilofophical loofenefs of expreffion, and, in one or two inftances, by inaccuracy of language. Even in the Preface, vegetation is called a body, and compared in this respect with water: these two bodies are faid alfo to purify air from attracting its phlogiston.' But we fhall give a fummary of the author's fyftem, in his own words.

• My general principles are thefe, that fire is matter; and that this matter, like every other matter that we know of, is capable of chemical attraction, or uniting with other bodies in the fame manner as alkalies and acids; that the bodies which it has the greatest attraction for are acids and earths or water; that thefe bodies by being united together form empyreal air; and that fire when chemically united with other bodies is then to be called phlogiston, as in oils, fpirits, bitumens, &c.

The different acids are capable of concentrating different proportions of fire with the earths; the nitrous and vitriolic concentrate it in that proportion as to form empyreal air, which burns with a crackling noise as if it were full of some combuftible matter. But if the phosphoric or marine acids be employed in the procefs they will attract a higher concentration of fire, and form inflammable air. And as bodies by being aerilized lofe their power of attraction, fo this empyreal air, when expofed to different bodies, will have its concentrated fire or phlogifton attracted, and become an acid, the phlogifton which neutralized the acid having left it.

The air is the great menftruum which concentrates the rays of the fun, and conveys it to animal and vegetable life, the former receiving more of the fun's influence by it than by the direct rays falling upon the animal, and being in that manner imbibed."

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In fupport of these principles, our author examines actual neutralized, and concentrated fire. Neutralized fire, in his language, is what we have been used to call phlogiston. Our author thinks it is derived from the fun alone, without being aware of the vast quantities of bituminous matters, at a depth where the fun can never reach, unless this earth, as Buffon fuppofes, was once a part of it.

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The author next examines the different kinds of air, particularly the inflammable and nitrous airs, the marine and fluor acid vapours, and that species of nitrous air, in which a candle will burn. In all his investigations, he falls into the common error, that airs are compofed of the bodies employed to procure them. In general, the air is only separated with different qualities, imbibed from the bodies with which it has been combined, and fometimes in a pure ftate, from those bodies having a fuperior attraction to the ingredients by which it was polluted. The remarks, however, on the nature of the inflammable nitrous air, are fometimes proper.

The Obfervations on Atmospheric Air are connected with the error we have just mentioned; but our author's method of explaining the appearance of fixed air, after common air has been expofed to phlogistic proceffes, is ingenious and confiftent with his own principles. It arifes, he fays, from the concentrated fire being attracted by phlogistic bodies, which, - as it had neutralized the acid ingredient in the air, in its ori ginal formation, now fuffers it to appear in its proper ftate. Our chemical readers, though they will own the ingenuity of the remark, will probably hefitate, with us, in pronouncing it to be juft. Many objections occur to it.

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On mercury, our author affords us no very particular fatiffaction. This chapter is chiefly composed of the opinions and experiments of others, on its calcination in confequence of agitation in water; a phænomenon not yet fatisfactorily explained. He next enquires how different Kinds of Air are affected by, and affect different Proceffes.' This chapter is fo mifcellaneous, the reafoning is fo loofe, and fo often erroneous, that it would lead us too far to abridge, or make any obfervations upon it. The foundation, viz. the compofition of airs, we have already explained.-The Uncertainty of Nitrous Air, as a Teft of the Salubrity of common Air,' is a fubject now fufficiently understood.

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The following chapter is on Fixed Air; but our author's reafoning refts on a foundation which we think unstable, viz. that pure air is only fixed air, with a greater fhare of phlogifton neutralizing the acid. Almost every experiment contradicts it.

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On the fubject of Vegetation, the author is a little inconfiftent. Let us take his own words, where he endeavours to reconcile the oppofite experiments of Priestley and Scheele.

Upon whatever principle vegetable circulation is conducted, it is certain there is an acefcent juice or fluid which circulates from their roots; this being expofed within the power of the air's attraction it decompounds it, and makes it foul air the fame as animal refpiration. This vegetable juice or fluid has equally the fame effect out of the veffels as in the vegetable, the fame as the animal fluids or blood, which equally decompounds the air when expofed either out or in the yeffels. The vegetable fluids being ftrongly acefcent in their circulation decompound the air (agreeable to the chemical table of attractions) and partly neutralize their acescency.

The juices received from the earth then attracts phlogiston from the air, and from the rays of the fun, from light, and from the heat, which in the fummer is generally confiderable; they being all concentrated by thofe acefcent fluids. The heavy gravitating earthy parts being attracted by the vegetable fibres are concreted with them, and their principal moisture being evaporated; part of the remaining fluids is fometimes dif charged as a high concentrated fluid in an aerial form, the fame as common air, only of a higher quality. We need not be furprised at this, fince they contain the three great constituents phlogifton, an acid, and water or earth.

The fun and light have a particular influence upon vegeta tion; for if a vegetable is kept in the dark it will fade, lofing its natural green colour; and its fluids will not have that high impregnation of phlogiston. In fhort it may just be said barely to vegetate. Dr. Priestley found that light was the great agent which made vegetables form empyreal air, that if they were placed in the dark no air would be generated. Mr. Ingenhouz found that vegetables in the day time would yield empyreal air, but in the night time foul air.

Thefe experiments directly fhew us how neceffary the fun is to vegetation, and to the formation of empyreal air. As the juices circulate within the vegetable they receive a higher impregnation of phlogifton or quiefcent fire; fo at laft their impregnation is fo high as to expand the fluids, and give them an aerial form; and agreeable to that obfervation of Mr. Ingenhouz, in the day time the impregnation is fo high as to form empyreal air, but at night, being bereft of the fun, it forms only foul air.'

If this means any thing, it is, that vegetables are capable of producing air, because they contain all the ingredients of the combination, when joined with the heat of the fun, Yet the author afterwards tells us, that if he is confirmed in one fact in this work? it is, that vegetables make the air foul. He informs us, indeed, that he avoided the aquatic plants in

his experiment; but we can tell him, that no plant affords pure air, except it be in a healthy ftate, and the quantity of air is in proportion to its ftrength and vigour. If then he tried the experiments in the ufual way, he would find the air injured by almost every plant, except an aquatic; for every other must be forced from its natural fituation before the experiment can be tried. Perhaps there is no fact better afcertained, than that healthy ftrong plants, in the fun, really feparate pure air. We should be glad to be informed by our author, howevery particle of air' can be expelled from water; and next, how the water can be prevented from re-absorbing air from the atmosphere, in fuch experiments? Neither boiling, nor the air-pump, will be fufficient; for after all these experiments, we are able to demonftrate air in water, by unequivocal experiments, though the water be not decompofed.

The nature and formation of pyrophori are explained on the author's general principles, viz. a large quantity of neutralized heat, flightly connected. But few will probably agree with him in thinking, that the heat of the fun is the caufe of 'the faltnefs of the fea.

The fun being the great author of fire, his rays upon this globe being concentrated, form fulphur, oils, bitumens, falts, &c. Upon the earth his rays form vegetation and animal life. Upon the immenfe waters the falts of the fea and animal life; for as there is no vegetation there comparatively, his rays are neutralized by the waters, and form the falt fluid. It is from this caufe that the fea has the greatest degree of faltnefs immediately upon that part of the globe where the fun is vertical, and in the autumn after he has given his full influence.'

We have felected this paragraph, not only to fupport our affertion, but to enter the strongest protest against this mode of philofophifing.

Our author's opinion of heat, and its combinations, are already known the tenth and eleventh chapters explain them. more fully; and various arguments are adduced, we think without fuccefs, to fhew that the caufticity of earths and falts do not depend fo much on the absence of fixed air, as on the prefence of neutralized and concentrated heat.

The following chapters are chiefly an account of difficulties, which, in our author's opinion, attend the common fyftems. We own that there are many difficulties in the aerial philofophy; but our author has magnified them, by not attending to fome neceflary diftin&tions, and increased them by his errors. He feems to think, however, that phlogifton is not attracted by air, but that it is neutralized by acids. The abforption of air by metals, in calcination, was known by Dr. Hales: it

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