by holding out to each industrious individual a near profpect of property and fecurity in his poffeffions, promifes, in the moft effectual manner, to enfure ftability to our conquefts, and popularity to our adminiftration; and will probably fet open the British territories as an afylum for the difcouraged hufbandman, the neglected artift, and oppreffed labourer from every quarter of Hindoftan.'

Such are the important objects which Mr. Halhed presents to his readers, as intimately connected with the ftudy of the Bengalefe tongue; and there can fcarcely be entertained the imalleft doubt that an attention to this language may be attended with confiderable advantages both to the European governors and the Afiatic fubjects.

The Romans, fays Mr. Halhed, a people of little learning, and lefs tafte, had no fooner conquered Greece, than they applied themfelves to the ftudy of the Greek: they adopted its laws even before they could read them, and civilifed themselves in fubduing their enemies. The English, who have made such a capital progrefs in the polite arts, and who are mafters of Bengal, may, with more eafe and greater propriety, add its language to their acquifitions; that they may explain the benevolent principles of that legiflation whofe decrees they enforce; that they may convince while they command; and be at once the difpenfers of laws and of fcience to an extenfive nation.'

In the above paffage the Author, furely, treats the Romans with too much feverity, condemning their want of tafte, in the fame moment that he mentions their careful ftudy of the Greek language, than which nothing can fet their good tafte in a more advantageous point of view. The fuccefs with which the Roman poets, orators, and hiftorians imitated the Grecian originals, difcovers no lefs tafte than judgment; and if we except the city of Athens, what other, on the face of the earth, was adorned with more literary genius than the capital of the Roman empire! The Romans indeed borrowed all their improvements in the fine arts from the Greeks, but what European nation has not done the fame? The Greek language, therefore, was not only an useful and ornamental, but, in fome measure, a neceffary branch of ftudy among all who pretended to tafte and refinement. It became the language of learning and philofophy over the whole Roman empire; but it never was adopted in the western provinces, at leaft as the language of legislation, policy, or even of common intercourfe and converfation. The Romans were peculiarly attentive to the diffufion of the Latin. language, as we are informed by hiftory, and as every one may be convinced from the great mixture of Latin in the modern languages of Europe. We much queftion, therefore, whether the example of the Romans in learning the Greek can, with any

propriety,

propriety, be urged as an argument with the English for learning the Bengalele language. Were England to follow the policy of Rome, fhe would be at the utmost pains to extend the knowledge of the English language over her Oriental dominions; if any books could be difcovered in the Arabic, the Perfian, or the Shanfcrit tongues, that deferved notice on account of the regularity of invention, beauty of compofition, and force of reasoning, which distinguish the Greek and Roman classics, England would be particularly careful to tranflate fuch writings, and to adopt them as her own; but fhe would never condefcerd to employ a foreign dialect as the medium of either commercial or political intercourfe with people whom the regarded as her fubjects.

ART. II. Experiments upon Vegetables, difcovering their great Power of purifying the common Air in the Sun fhine, and of injuring it in the Shade, and at Night, &c. By John Ingenhoufz, Counfelior of the Court, and Body Physician to their Imperial and Royal Majefties, F. R. S. &c. 8vo. 5 s. fewed. Elmfly. 1779.

T

HOSE who have attended to the numerous and important difcoveries made by Dr. Priestley, particularly on the subject of Air, must have been greatly ftruck with the laft observations communicated by him to the public; relative to the production of the pureft dephlogisticated air, apparently proceeding from a green and undoubtedly vegetable fubftance, which appears at the lower part of an inverted receiver filled with water, and which has for fome time been expofed to the light of the fun *.

During the last fummer Dr. Ingenhoufz has fuccefsfully profecuted this interefting fubject; and in the prefent work has communicated to the public the very extraordinary refults that attended his inveftigation of it. For the purpose of profecuting his inquiries, in a proper fituation, and without interruption, he informs us, that he difengaged himself from the noise of the metropolis, and retired to a fmall villa; and that this work contains a part of the refult of above 500 experiments, which were all made in lefs than three months: having begun them in June, and finished them in the beginning of September laft, working from morning till night.' Whatever I have been able to deduce from my labours,' he adds, is done in a hafty manner; as my stay in this country was far too limited to allow me to compofe my work in a regular and more fatisfactory manner.'

The ingenious Author had not long been employed in interrogating nature, in his rural retreat, before he faw a moft im

* See his Experiments and Obfervations on various Branches of Natural Philofophy; and our particular account of this fubject, in the first article of our Review for September laft, page 165, &c.

portant

portant fcene opened to his view.' In the following recapitulation we have collected together the principal deductions which he made from his experiments.

He obferved that plants have not only a power of correcting bad air in 6 or 10 days, by growing in it, as the experiments of Dr. Priestley indicate; but that they perform this important office, in a complete manner, in a few hours; and that this wonderful operation is by no means owing merely to the vege tation of the plant, but to the influence of the light of the fun upon it:

That plants, expofed to the light of the fun, have likewise the furprifing faculty of elaborating the air which they contain, and have abforbed from the common atmosphere, into real dephlogifticated air; which they emit, principally from the under furface of their numerous leaves, into the common mass;—that this operation commences only after the fun has appeared for fome time above the horizon, and is carried on more or less brifkly in proportion to the clearness or dulnefs of the day, or the more or less favourable expofition of the leaves to the rays of the fun; and that this production of pure air diminishes towards the clofe of the day, and ceafes entirely at fun-fet, except in a few plants which perform this function fomewhat longer than others:

That acrid, ill-fcented, and even the moft poisonous plants perform this office in common with the mildest and the most salutary; though fome elaborate dephlogifticated air more copiously than others, particularly fome of the aquatic plants:

That, on the contrary, all plants whatever emit a noxious air, in the night; and even thofe which excel others in yielding the pureft air in the fun-fhine, furpafs them in the power of infecting the circumambient air in the dark; to fuch a degree that, even in a few hours, they render a large quantity of good air fo noxious, that an animal confined in it lofes its life in a few feconds; and that, even in the day-time, plants shaded by high buildings, or growing under a dark fhade of other plants, emit an air that is noxious to animals:

That the flowers of plants, univerfally, render the furrounding air highly noxious, equally by night and by day; that their roots, detached from the ground, poffefs the fame property, fome few excepted; but that fruits in general, even the moft delicious, have this deleterious quality (though principally in the dark), to fuch an aftonishing degree, as to endanger the life of a perfon who fhould happen to be fhut up in a small and clofe room, where a great quantity of them were stored up:

And lastly, that the light of the fun, fingly, has not the power of purifying any quantity of air expofed to it, without the concurrence of the plants: on the contrary, from one of the Author's

Author's experiments it feemed rather to have contaminated it. We fufpect however that, in this particular cafe, the air expofed to the fun was contaminated by his heat, expelling fome portion of fixed air from the pump water by which it was confined, in the experiment; from which it would be more copiously extricated, than from the other portion of the fame water that was kept cooler, by being placed in the fhade.

This epitome of the Author's principal conclufions is deduced from 125 experiments, circumftantially, though with proper concifenefs, related in the fecond part of this work; where they are methodically arranged under different heads. The method generally employed by the Author in making these experiments is the following:

A glass jar is first filled with fresh pump water, which appears to him to be beft adapted to the purpofe; because, generally containing air already, particularly fixed air, it is not fo likely to absorb any part of that emitted by the plants. This jar, thus completely filled, is inverted in a tub of the fame water, which is then expofed to the open air, or rather to the fun-fhine. The plants, or rather their leaves, are then introduced into the jar, through the water. Thus,' fays the Author, the leaves continuing to live*, continue alfo to perform the office they performed out of the water, as far as the water does not obftruct it. The water prevents only new atmospheric air being abforbed by the leaves; but does not prevent that air, which already existed in the leaves, from ouzing out.'

This air, in fact, does ouze out; for it foon appears upon the furface of the leaves, generally in the form of round bubbles, which increafing in fize fucceffively, rife up to the top of the jar. The air thus collected is found to be true dephlogifticated air; of a greater or lefs degree of purity, according to the nature of the plant which emitted it, bnt principally in proportion to the greater or lefs quantity of light to which it had been expofed, and to the time of the expofure. In fome plants, particularly the Nymphaea alba, the bubbles fometimes fucceed each other fo quickly, as to rife from the fame fpot almost in a continued ftream.

* In confequence of the Author's manner of expreffing himself in this place, as well as in many other paffages, and from his filence on the fubject, the reader will perhaps find the fame difficulty that occurred to us, in determining whether, in the generality of his experiments, the leaves and talks of plants introduced into the jar were previously feparated from the refpective plants, or were ftill connected with them. On making inquiries on this fubject, before the Author left the kingdom, we learned that, when the contrary is not expreffed, the different leaves, &c. introduced into the jar were previously feparated from their respective plants.

There

There are many varieties in this procefs, depending on the peculiar organifation of the leaves in different plants. Some begin very early in the morning to yield dephlogifticated air, and ceafe late in the evening; for inftance, potatoe and malva leaves. Others begin the operation very late in the morning, and ceafe very early in the evening; for inftance, the leaves of laurocerafus. The leaves of potatoe plants yield the air bubbles immediately; thofe of malva, in a few feconds; those of the walnut tree, in a few minutes; and the leaves of laurocerafus much later.

The Author infers from his experiments, that the pure or dephlogifticated air, thus obtained from plants expofed to the fun's light, did not antecedently exift in the leaves, in this pure. ftate; but is only fecreted out of them, when it has undergone a purification, or a kind of tranfmutation.'-Thus fome leaves of an apple-tree being treated in the manner above described, (excepting their being placed near a fire, inftead of being expofed to the fun); a great deal of air was indeed obtained from them, but it was found to be fo bad as to extinguifh flame.

Leaves that had been warmed in the fun's rays, and then haftily plunged into the inverted jar filled with cold water, were found to be remarkably quick in forming air bubbles, and in yielding the best dephlogisticated air. Nor is any dephlogisticated air to be obtained in a warm room, unless the fun fine upon the jar containing the leaves. From hence the Author concludes that the production of this pure air does not depend on the warmth, but chiefly, if not folely, on the light of the fun.

It has been already, in part, obferved, that plants exposed to clear day-light, or fun-fhine, will, in a fhort time, purify air that has been rendered unfit for refpiration; fo as to make it equal to common or atmospheric air in purity. A fingle leaf of a vine fhut up in an ounce phial containing air contaminated by breathing, fo that a candle would not burn in it, restored it to a state of purity equal to that of common air, in the space of an hour and a half,

That the Reader may form fome judgment of the quantity of dephlogifticated air, which the Author obtained from the leaves of plants, treated in the manner above defcribed; we shall felect two inftances from the experimental part of this work.

One hundred leaves of the Najlurtium Indicum (which however the Author reprefents as furpating the generality of plants in the production of dephlogifticated air, both with refpect to quantity and quality) being put into an inverted jar holding a gallon, and filled with pump water, were expofed to the fun two hours, between ten and twelve. During this time they yielded as much dephlogifticated