the prohibition of any further exportation from Africa, a fmaller inconvenience than is pretended by the interefted advocates for this odious traffic; whofe arguments in its favour are the fordid pleadings of mean mercantile fpirits, whom an iniatiable thirft of gold would lead to juftify any thing, however difhonourable, that was not punishable by human laws, and which lured them with the profpect of gain. What commercial advantages must be refigned by an abolition of this trade, or how they may best be compenfated, we prefume not to determine; but we hope and truft that a British Parliament, while it encourages commerce in the moft liberal and beneficent fenfe, will fhew a fpirit of national honour equal to that of the Athenians; who, by rejecting the propofal of Themiftocles to deftroy the Spartan fleet, held forth this generous leffon to communities, as well as to indivi duals, that nothing ought to be purfued as advantageous, which is inconfiftent with the dictates of justice and humanity.

ART. IX.

Lettre de M. M. Paets Van Treeftwyk et Deiman à M. De La Metberie, &c. i. e. A Letter from M. PAETS VA TROOSTWYK and Dr. DEIMAN to M. DE LA METHERIE, on a New Method of Decom. pofing Water.

F this letter, which is intended for one of the French journals, we have been favoured with a manufcript copy; and, as in the prefent ftate of chemical philofophy, the information which it contains may be acceptable to many of our readers, we are happy in having this early opportunity of communi. cating it.

The production of water from the combuftion of inflammable with dephlogisticated air, and its reduction into these elaftic fluids, are points of importance, not only in themselves, but also as they are connected with a new and very ingenious chemical theory. The experiments which have hitherto been adduced in proof of these two propofitions, have been liable to fome objec tions. In the former cafe, the fluid produced has been found to exhibit marks of acidity, which have rendered the conclufion uncertain; and, in the latter, the production of inflammable air has been afcribed to fubftances employed in, the proceís, which are known to yield this elaftic fluid by means of heat alone. The prefent writers, fenfible of the force of thefe objections, had long continued their attachment to the Stahlian hypothefis; but they are now become converts to M. Lavoifier's theory, in confequence of fome experiments which they performed with their ingenious friend Mr. Cuthbertfon; and which feem to leave no room for the objections above-mentioned.

The principal apparatus which is requifite for these experiments, is a ftrong glafs tube, about twelve inches long, the

bore

bore of which is an eighth part of an inch in diameter: it is hermetically fealed, at the upper end, with a piece of gold wire, which projects an inch and half within the tube: about eight inches from the top, the tube is bent, firft upward, and then downward again, fo as to form two adjacent arches in oppofite directions: the lower end is open; and, into this, another piece of wire, either of gold or of platina, is introduced, the extremity of which is about an inch and a quarter diftant from that of the other. The tube, thus prepared, was filled with diftilled water, deprived of its air by means of an air-puntp; and its open end immersed in a vessel containing the fame fluid. Strong electrical fhocks, from a jar of a fquare foot of coated furface, were then tranfmitted through the water; from which, on every explofion, very small bubbles of air were observed to rife, and unite in the top of the tube. Six hundred of these fhocks having been given, the air formed a column an inch and three eighths in length, which when fo far increafed as to extend below the end of the uppermoft wire, took fire on the explosion paffing through it; the refiduum was only a fmall bubble part of an inch in diameter, and was reduced to half this dimenfion, by making a fecond electric fhock explode through it. This refiduum was fuffered to efcape, and the experiment was repeated three times with the fame water. The refults of these four trials were exactly alike; except that, after each combuftion, the refiduum was lefs in bulk, than after the preceding, till the diameter of the laft was not more than part of an inch.

In order to infure the fuccefs of thefe experiments, it may be proper to obferve that the shocks ought to be as ftrong as the tube will bear, without breaking: in those above described, the brass ball, in contact with the fealed end of the tube, on which the charge exploded, was an inch distant from that at the extremity of the prime conductor: the ends of the wires ought alfo to be fo far removed from each other, that the electricity may not pass without an explofion. When the open end of the tube was immersed in mercury, it was foon broken by the electric shocks; this fluid making too much refiftance to the expansion of the water. To prevent accidents of this kind, these ingenious philofophers found it expedient to admit, into the open end of the tube, a fmail bubble of atmospheric air, which remained fufpended in the top of the arch, and was feparated from the fealed end, by the intervening column of water.

The combuftion, and the confequent diminution of the elaftic fluid thus produced, were fufficient proofs that it was a mixture of inflammable and dephlogifticated air: that this is not to be afcribed to air contained in the water, or adhering to the infide of the tube, is argued from the diminution of the refiduum on every repetition of the experiment with the fame water: for

S14

what

what could thus affe& the refult, could be no other than common or atmospheric air, of which a part only is dephlogifticated; but in this cafe, when the procefs was repeated, the refiduum, inftead of diminishing, would have been greater, and the combuftion lefs complete than before, in proportion to the confumption of the dephlogisticated part of the fuppofed air. But M. De La Metherie, in his explanation of Mr. Cavendish's experiments, has fuppofed that inflammable air is an elemental part of the nitrous acid, and is generated by the electric explosion. In order to determine this point, Meff. VAN TROOST WYK and DEIMAN tranfmitted electric explofions of the fame force through oil of vitriol, and alfo through the nitrous acid; from these fluids, alfo, air-bubbles arofe, though lefs rapidly than from water, and leaft fo from the oil of vitriol; but, on paffing through the air thus produced, the electric difcharge effected no combuftion; which proved that it was not, as in the former experiment, a mixture of inflammable and dephlogifticated air; on the ufual trial, it appeared to be entirely the latter.

From thefe premifes, M. VAN TROOSTWYK and Dr. DEIMAN conclude that the inflammable and dephlogifticated air, generated in thefe experiments, must be produced from the water; and as, by combuftion, thefe elaftic fluids are reduced to water, they confider the whole procefs as a fynthetical, as well as analytical, demonftration of M. Lavoifier's hypothefis; and infer that the acid, which has fometimes been found in the water thus produced, is merely an accidental circumftance, of no force as an objection to the theory.

To account for this acid, which is always obferved to be more perceptible in proportion to the purity of the dephlogifticated air employed in the procefs, thefe gentlemen obferve, that dephlogifticated air has a greater affinity to inflammable than to phlogifticated air; and that it will not unite with the latter, except when there is not inflammable air fufficient to faturate it.

If then, the proportion of dephlogifticated air be fuch, that the whole of it, on combuftion, can be combined with the inflammable air, the fluid produced will be pure water, and the refiduum will be phlogistic air. But if there be a fuperabundance of dephlogifticated air, that, which remains after the faturation of the inflammable air, will combine with the phlogistic refduum; and, with this, form the nitrous acid: fo that the fluid obtained will, in this cafe, be a compound of water and acid; and, if there be any refiduum, it will confift only of the dephlogifticated air, which remained after the other claffic fluids were faturated.

But, perhaps, it may be aked, whence proceeds the combination of phlogifticated with dephlogifticated air, which is here fuppofed to form the nitrous acid (and which, hitherto, the

electric explosion has been deemed the only means of effecting)? Thefe gentlemen acknowlege that they are not yet able to anfwer this question with certainty; they think, however, that it may be owing to the light which accompanies the combuftion. M. Berthollet difcovered that nitrous acid, when expofed to light, yields dephlogisticated air; and they have themselves obferved that it has a fimilar effect on the vitriolic acid placed in the focus of a burning glafs. And, if in the decompofition of these acids, the effects of light and of electricity be thus analogous, it is not improbable that they may likewife be fo, in compofing the nitrous acid, by combining its conftituent principles.

Decifive as this experiment hitherto appears to us, we must fufpend our opinion concerning the theory which it is fuppofed to demonftrate, till it has been repeated and diverfified by others, who may examine it with leis predilect on than its propofers may be imagined to entertain. We mean not to accufe Meffis. VAN T. and D. of inaccuracy or precipitation; but we know, by experience, that the ardour of mind, infpired by the idea of a difcovery, is apt to render the moit careful obferver inattentive to fome minute circumftance; which may be afterward perceived by thofe, whofe oppofite opinions lead them to investigate the procefs with greater diffidence, and more fcrupulous precifion.

ART. X.

Geographifche Gefchichte des Menchen, &c. i. e. A Geographical Hiftory of Man, and of the Quadrupeds which are difperfed over the different Parts of the Earth, &c. By Profeffor ZIMMERMAN.

HAV

[Article Concluded from the last Appendix.]

AVING laid before our readers, in a former Review, a general account of this work; and having prefented them with fuch extracts from the two firft volumes, as may enable them to form fome ideas of the manner in which the Profeffor has executed his plan; we fhall proceed to give a concife account of the contents of the third volume, which is principally devoted to various inferences and fpeculations, deduced from the fyftem which he has attempted to eftablish. He remarks, in the preface, that it will now appear not to have been his chief object to arrange every fpecies of mouse and weafel in the register of nature, and to count all their teeth for this purpose. This expreffion has rather an hoftile appearance: it feems to aim a very fmart blow at the Linnéan fyftem; but, by the fubfequent part of the fentence, we find his hand is checked, and it turns to a friendly ftroke, like a gentle pat on the cheek: for he adds,

However applicable fuch characteristic marks may be to natural history, and I fatter myfelf that I have made an advantageous ufe of them in my general view of quadrupeds, yet it has not been the principal object of this work. My chief aim has been to trace every

where

where the plan of wisdom in the distribution of animals; to difcover thofe regulations which prove fo advantageous to man; to draw inferences from zoology refpecting the temperature of different regions; and from the ancient ftate and arrangement of things, to examine how far the laws of zoology may reflect light on the hiftory of

man.'

In a preliminary difcourfe, he treats of the immenfity of vital exiftence; and then proceeds, in the 4th part, to the application of zoology to the history of the earth. In the profecution of this defign, he compares together the different zones, as to the fum of their animal productions, and first inquires into the general laws of nature respecting the land-then the population of the fea-the diftribution of quadrupeds over the earth-eftimate of the proportion between the known and unknown parts of the globe- the proportion between the various fpecies of animals already known, and those of which we may, at prefent, be supposed to be ignorant-the babitations of all the quadrupeds hitherto known in the five parts of the world-inquiry into the laws which take place respecting the diftribution of animals-their emigrations-how far the hiftory of animals will illuftrate the history of the earth-and the history of the buman race-comparative view of the temperatures of different lands, refpecting certain quadrupeds.

From this copious bill of fare, the reader will easily perceive how impracticable it will be for us to give him a taste of each article. The fame excellencies and defects are confpicuous in this third volume, which we remarked in the two preceding. Many new and important obfervations are intermixed with tedious digreffions, and needlefs repetitions. We do not mean to infinuate that there is an intentional difplay of very extenfive reading; we rather imagine that the Profeffor has been more affduous to collect ample materials, than attentive to a concife and judicious arrangement; and that he has felt too great a reluctance to permit any article which he has been at the pains to tranfcribe into his common-place-book, to remain there unemployed.

1 he preliminary difcourfe contains fome very juft and striking obfervations on the infinitude of life which is diffufed through all nature; clearly indicating that life is the grand object of creation. Thofe parts which poffefs it not, he remarks, are manifeftly deftitute, from the law of abfolute neceffity, while the moft boundlefs liberality is difplayed in the production of living organized bodies. The obvious law of nature is, that the jum of the different kinds of organized bodies shall increase in propertion to the degrees of fenfation and animation. Thus the living vegetable world leaves the unorganized mineral kingdom far be

By the fifth part of the world, M. ZIMMERMAN means New Holland.