« PreviousContinue »
by holding out to each industrious individual a near profpeet of property and security in his posicflions, promises, in the most effectual manner, to ensure stability to our conquests, and popularity to our adminiftration; and will probably set open the British territories as an asylum for the discouraged husbandman, the neglected artist, and oppressed labourer from every quarter of Hindoftan.'
Such are the important objects which Mr. Halhed presents to his readers, as intimately connected with the study of the Bengalese tongue; and there can scarcely be entertained the imallest doubt that an attention to this language may be attended with considerable advantages both to the European governors and the Afiatic subjects.
The Romans, says Mr. Halhed, a people of little learning, and less taste, had no sooner conquered Greece, than they applied themselves to the study of the Greek: they adopted its laws even before they could read them, and civilised themselves in subduing their enemies. The English, who have made such a capital progress in the polite arts, and who are masters of Bengal, may, with more ease and greater propriety, add its language to their acquisitions ; that they may explain the benevolent principles of that legislation whose decrees they enforce; that they may convince while they command; and be at once the dispensers of laws and of science to an extensive nation.'
In the above passage the Author, surely, treats the Romans with too much feverity, condemning their want of taite, in the fame moment that he mentions their careful study of the Greek language, than which nothing can set their good taste in a more advantageous point of view. The success with which the Ro. man poets, orators, and historians imitated the Grecian originals, discovers no less taste 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 same? The Greek language, therefore, was not only an useful and ornamental, but, in lame measure, a neceffary branch of study among all who pretended to taste and refinement. It became the language of learning and philosophy over the whole Roman empire; but it never was adopted in the western provinces, at least as the language of legislation, policy, or even of common intercourse and conversation. The Romans were peculiarly attentive to the diffufion of the Latin language, as we are informed by history, and as every one may be convinced from the great mixture of Latin in the modern languages of Europe. We much question, therefore, whether the example of the Romans in learning the Greek can, with any
propriety, be urged as an argument with the English for learning the Bengalele language. Were England to follow the policy of Rome, she would be at the utmost pains to extend the knowledge of the English language over her Oriental dominions; if any books could be discovered in the Arabic, the Persian, or the Shanscrit tongues, that deserved notice on account of the regularity of invention, beauty of composition, and force of realoning, which distinguish the Greek and Roman clasics, England would be particularly careful to translate such writings, and to adopt them as her own ; but she would never condescerd 'to employ a foreign dialect as the medium of either commercial or political intercourse with people whom the regarded as her subjects.
Art, III. Experiments upon Vegetables, discovering their great Power
of purifying the common Air in the Sunshine, and of injuring it in obe
HOSE who have attended to the nu!nerous and import
ant discoveries made by Dr. Priestley, particularly on the subject of Air, must have been greatly ftruck with the last observations communicated by him to the public; relative to the production of the purest dephlogisticated air, apparently proceeding from a green and undoubtedly vegetable substance, which appears at the lower part of an inverted receiver filled with water, and which has for some time been exposed to the light of the sun*.
During the last summer Dr. Ingenhousz has successfully prosecuted this interesting subject; and in the present work has communicated to the public the very extraordinary results that attended his investigation of it. For the purpose of prosecuting his inquiries, in a proper situation, and without interruption, hé informs us, that he disengaged himself from the noise of the metropolis, and retired to a small villa; and that this work contains a part of the result of above 500 experiments, which were all made in less than three months : having begun them in June, and finished them in the beginning of September last, working from morning till night.'-- Whatever I have been able to deduce from my labours,' he adds, ' is done in a haly manner; as my stay in this country was far too limited to allow me to compose my work in a regular and more satisfactory manner.'
The ingenious Author had not long been employed in interrogating nature, in his rural retreat, before he saw' a most important fcene opened to his view.' In the following recapitulation we have collected together the principal deductions which he made from his experiments.
* See his Experiments and Observations on various Branches of Na. tural Philofophy; and our particular account of this subject, in the first article of our Review for September last, page 165, &c.
He observed that plants have not only a power of correcting bad air ir 6 or lo 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 vegetation of the plant, but to the influence of the light of the sun upon it:
That plants, exposed to the light of the sun, have likewise the furprising faculty of elaborating the air which they contain, and have absorbed 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 sun has appeared for some time above the horizon, and is carried on more or less briskly in proportion to the clearness or dulness of the day, or the more or less favourable exposition of the leaves to the rays of the fun; and that this production of pure air diminishes towards the clofe of the day, and ceases entirely at sun-set, except in a few plants which perform this function somewhat longer than orhers :
That acrid, ill-fcented, and even the most poisonous plants perform this office in common with the inildest and the most falutary; though some elaborate dephlogisticated air more copiously than others, particularly some of the aquatic plants :
That, on the contrary, all plants whatever emit a noxious air, in the night; and even those which excel others in yielding the purest air in the sun-fhine, furpass them in the power of infecting the circumambient air in the dark; to such a degree that, even in a few hours, they render a large quantity of good air fo noxious, that an animal confined in it loses its life in a few seconds; and that, even in the day-time, plants Thaded by high buildings, or growing under a dark Thade of other plants, emit an air that is noxious to animals :
That the flowers of plants, universally, render the surrounding air highly noxious, equally by night and by day; that their roots, detached from the ground, possess the same property, some few excepted; but that fruits in general, even the most delicious, have this deleterious quality (though principally in the dark), to such an astonishing degree, as to endanger the life of a person who should happen to be shut up in a small and close room, where a great quantity of them were stored up:
And lastly, that the light of the sun, singly, has not the power of purifying any quantity of air exposed to it, without the concurrence of the plants : on the contrary, from one of the
Author's experiments it seemed rather to have contaminated it. We suspect however that, in this particular case, the air exposed to the sun was contaminated by his beat, expelling some 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 same water that was kept cooler, by being placed in the shade.
This epitome of the Author's principal conclufions is deduced from 125 experiments, circumftantially, though with proper conciseness, related in the second 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 best adapted to the purpose; because, genesally containing air already, particularly fixed air, it is not so likely to absorb any part of that emitted by the plants. This jar, thus completely filled, is inverted in a tub of the same water, which is then exposed 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,' says the Author,
the leaves continuing to live *, continue also to perform the office they performed out of the water, as far as the water does not obstruct it. The water prevents only new atmospheric air being absorbed 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 soon appears upon the surface of the leaves, generally in the form of round bubbles, which increasing in fize successively, rise up to the top of the jar. The air thus collected is found to be true dephlogirticated air; of a greater or less degree of purity, according to the nature of the plant which emitted it, bnt principally in proportion to the greater or less quantity of light to which it had been exposed, and to the time pf the exposure. In some plants, particularly the Nymphæa alba, the bubbles sometimes succeed each other so quickly, as to rise from the fame spot almost in a continued stream.
* In confequence of the Author's manner of exprefsing himself in this place, as well as in many other passages, and from his filence on the subject, the reader will perhaps find the same difficulty that oc. curred to us, in determining whether, in the generality of his experia ments, the leaves and talks of plants introduced into the jar were previously separated from the respective plants, or were still connected with them. On making inquiries on this subject, before the Author left che kingdom, we learned that, when the contrary is not exprerfed, the different leaves, &c. introduced into the jar were previously separated from their respective plants.
There are many varieties in this process, depending on the peculiar organisation of the leaves in different plants. Some begin very early in the morning to yield dephlogisticated air, and ceale late in the evening; for instance, potatoe and malva leaves. Others begin the operation very late in the morning, and cease very early in the evening; for instance, the leaves of laurocerasus. The leaves of potatoe plants yield the air bubbles immediately; those of malva, in a few seconds; those of the walnut tree, in a few minutes ; and the leaves of laurocerasus much later.
The Author infers from his experiments, that the pure or dephlogisticated air, thus obtained from plants exposed to the fun's light, did not antecedently exist in the leaves, in this pure itate ; but is only secreted out of them, when it has undergone a purification, or a kind of transmutation.'-Thus some leaves of an apple-tree being treated in the manner above described, (excepting their being placed near a fire, instead of being exposed to the sun); a great deal of air was indeed obtained from them, but it was found to be so bad as to extinguish flame.
Leaves that had been warmed in the sun's rays, and then hastily 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 sun shine 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 solely, on the light of the fun.
It has been already, in part, observed, that plants exposed to clear day-light, or sun-hine, will, in a sort time, purify air that has been rendered unfit for respiration; so as to make it equal to common or atmospheric air in purity. A single leaf of a vine fiut up in an ounce phial containing air contaminated by breathing, so 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 dephiogisticated air, which the Author obtained from the leaves. of plants, treated in the manner above described; we lhall select two instances froin the experimental part of this work.
One hundied leaves of the Naturtium Indicum (which however the Author represents as furpating the generality of plants in the production of dephlogisticated air, both with respect to quanrity and quality) being put into an inverted jar holding a gallon, and filled with pump water, were exposed to the sun two hours, between ten and twelve. During this time they yielded as much