pulation diminishes here daily. At that time the number of inhabitants amounted to 116,000 men; but at prefent we fhould not certainly find an equal number there. It would be neceffary to re-establish harmony in all the orders of the ftate, confounded together. The right of nobility has been taken away by the Genoefe from the moft ancient families, fo that there is now scarce any difference between those who have formerly been gentlemen, and the peasants. There were no more offices, no kind of education for children'; and the republic, would not admit them to any ecclefiaftical or military dignities. Their new chief has repaired all these diforders as well as he was able, that is to fay, he has prevented them from increafing as much as they otherwife would. His precarious authority, ever tottering-his life even every inftant in danger have not permitted him to do all the good he wifhed, and of which his genius and wifdom rendered him capable.

As for the re, you may eafily conceive, Sir, by this account, from whence arifes the invincible hatred of the Corficans againft the republic: the latter feems to have exerted every effort to deftroy thefe people; they had even forbidden them every kind of trade annually feized upon their oils and other commodities at a very low price, and made them pay very dear for falt, iron, copper, and the other articles they might want. In a word, they were treated more like favages, whom it was intended to exterminate, than like fubjects who were to be protected. It is to be

T

HE fcience of nature feems

to have three degrees. The firft fixes our attention to the outfides, and teaches us to collect external characters, in order to enable us to diftinguish various natural bodies; and this is the proper object of natural history." If we penetrate ftill deeper by our contemplation, and examine the general qualities of matter (its extenfion, impenetrability and vis inertia) in regard to its peculiar relations; it is that which is commonly called natural philofophy (Phyfica). But chemistry is the innermost part, fince it examines the material elements, their mixtures, and proportions to one another. The firft teaches us the elementary rudiments, the alphabet of the great book of nature; the fecond inftructs in fpelling; and the third, to read diftinctly. The two first therefore are no more than fubfidiary fciences, which conduct us to the laft, as the proper great object.

Since all fingle qualities of

bodies depend upon their structure and compofition; it follows neceffarily, that all our occupa tions with material and corporeal fubftances, never can obtain any degree of perfection, without the affiftance of natural philofophy. And fince commonly the proper intention of our occupations is directed either to our health, the neceffaries of life, or our comfort, three different claffes of practical fciences are from thence derived, medicine, hufbandry, and the arts. We fhall in the most concise manner confider the connection of chemistry with each of them.

In the times when chemistry was chiefly founded on various nonfenfical hypothefes, and was nevertheless applied with a blind zeal and the most perfect confidence not only to the cure of all infirmities and difeafes, but even to the obtaining of immortality itfelf; then it could be productive of nothing but detriment and mifchief in the fcience of phyfic.

We have no knowledge of bodies a priori: every intelligence about them, must be acquired by proper obfervations and experiments. But to discover and purfue fuch experiments as really illuftrate the point we are in fearch of, requires not only skill, and a peculiar application, but alfo the moft impartial love of truth; in order not to be enfnared by the pleafing defire of drawing general conclufions from a few data of precarious certainty. It leffens no doubt our trouble, and flatters our vanity, to be able to difclofe in a moment the whole courfe of nature. Man is befides naturally indolent, and much inclined to

be captivated by imagination mor than by reality. The confeffion therefore, that we really know no more than what we know, is even in our days, when the experimen-, tal method is confidered as the only right and true method, very difficult and humiliating but fince all fciences have their roads of error, their abuses and follies (which unfortunately always feduce the greater part of mankind) it is chiefly owing to this precipitation and fancy, that fuch monfters are produced.

Every thing going forward in our body, is done either in a mechanical or in a chemical way; fince the operations of the immaterial foul have nothing to do with it. Our food is diffolved, and changed on its road in paffing from the mouth, through the ftomach, entrails and other inteftines, by means of the faliva, the liquor gafiricus, the gall, the chyle, &c. fo that in feveral places various matters are prepared, all of which are neceflary for the increafe and fupport of the machine! The lungs moreover add by their conftant motion, various fubtle particles by means of the abforbing veffels, and again by the exhaling veffels, carry off others. The leaft irregularity in all these natural functions, lays of courfe the foundation for many infirmities and difeafes. Thefe ought to be prevented or cured by fuch medicines as have nothing noxious in other refpects capable of obstructing the main tendency, and which contain nothing fuperfluous; for if they were even in themselves harmless, they might however become hurtful by their quantity. It is therefore no

doubt

doubt a great advantage, to be able to concentrate the powers of feveral ounces into a few grains.

Did we exactly know, after chemical principles, the natural functions going forward in the body, the caufes of difeafes, and the effects of medicines; chemistry would most certainly operate mi

racles.

But I forefee already what may be objected to this affertion with fome reason, viz. "Though fuch knowledge would be a moft excellent thing, it would however be rather the object of wishes than fuch as might be fuppofed or hoped for in the human body every operation goes forward very fecretly; nor is there any glafs window to admit the refearches of the inquifitive: it is by no means right to play with the lives of men, and it would be highly unjustifiable to endanger them by uncertain experiments, &c." I reply, this is perfectly right; at the fame time it by no means juftifies us in neglecting the right means of obtaining information; and ftill lefs in treating them with contempt. Whatfoever is difficult, is not therefore impoffible always. The more investigation and trouble an invention cofts, the more honour be obtainmay ed by it; especially if it has for its object, health, the most precious enjoyment a man can be bleffed with. If a man be only poffeffed of a truly fundamental knowledge, many things may be difcovered without the leaft danger. Higher chemistry has difcovered many and various new manipulations, and by recalling to our minds one or the other inftance, we fhall be enabled to

judge what more may with reafon be expected.

Several kinds of difeafes fpread devastation over extenfive countries, over people of all ranks and denominations; without being however infectious in themselves. Thefe cannot, properly fpeaking, be derived from the mode of living; which in those who are attacked with the evil, is widely different; there must therefore exift a general caufe, which affects equally the richer and the poorer. The atmosphere is the fame for all; during feveral years its weight and temperature have been obferved; and this has furnished feveral explications, which how.. ever are not fatisfactory for the explanation of all its phænomena. Its conftituent parts therefore ought to be better known. The vapours and heterogeneous particles, are different in regard to quantity, as well as to quality. Befides chemiftry teaches us, that this elaftic fluid furrounding our globe, is at all times, and every where, a compound of three very different fubftances, viz. of good air, foul air, and aërial acid. The first is called by Dr. Priestley, if not wrongly, however fomewhat improperly, phlogisticated air. Mr. Scheele calls it with more reafon empyreal air, (fire air) fince this alone gives life to fire, when the other two kinds of air extinguifh the flame of a candle or fire. The laft kind is commonly called fixed air: but I flatter myself to have fatisfactorily proved by experiments, that it is a peculiar acid. The nature of the firft kind, has as yet been very little inveftigated; however by analogy it feems to be hardly any thing

but

for carrying off from the lungs, the noxious particles, or introducing into them a vivifying pabulum. But however noxious aerial acid is for found lungs, it is nevertheless of great utility in the prime via. Purulent lungs not only bear aërial acid, but they are even cured by it: and no fooner is the cure performed, than its inhalation becomes again dangerous. But though there be ever fo much left for investigation, we may apply that for ufe which has already been difcovered. It is for inftance well known, that the air of the atmosphere may be examined in regard to its fitnefs for refpiration; a difcovery which bids fair to yield, in a very fhort time, the most important illuftrations. If fuch obfervations were made at the fame time in dwelling-rooms, infirmaries, and the open air, and were continued with fome degree of accuracy, thould certainly difcover the caufes of many phænomena, which hitherto have remained inexplicable. Thus much we know already; that wounds and ulcers are with difficulty kept from going into mortification in corrupted, foul air; whereas on the other fide, the immenfely acute pains accompanying the cancer (that dreadful ailment) are in a few days not only mitigated and affwaged by the external ufe of aërial acid, but the loathfome aperture is alfo confiderably diminished. The compafs of a preface not only prevents me from entering into a fuller difcuffion of this important fubject, but also from producing mere inftances of its utility; I cannot help however mentioning in a few words only, that the ob

we

fervations on aërial acid have already fpread a new light on the method of effaying and imitating, by art, medicated waters; and on their application and ufe in the cure of the fcurvy, and other internal putrid difeafes.-The true analysis of the calculi from the kidneys and bladder, has enabled us to judge with precision of the beft remedies against the gravel. The discovery of the inner conftitution of arfenic, made us better acquainted with the manner by which its dreadful effects are pro duced; and thereby the best means were pointed out, both to extinguish its poifonous quality, and likewife to mitigate and di rect its effect for better purposes. How fimplified are at prefent many compounded remedies; and how fafe and little perilous, are many preparations of the moft acrid and corrofive fubftances? How many abfurd mixtures, decompounding and counteracting themfelves, have not of late been rejected? How many falfe theories of diseases, and their caufes, are there not daily expofed, and fhewn to be without any foundation, by means of chemistry? Sugar was faid to contain lime, in order to account for certain effects afcribed to fugar; though it contains not an atom of it. calculi of the kidneys and the bladder were faid to be calcareous; though they contain at the most only one half of calcareous fubftance. And fo in many more inftances, which it would be too tedious to enumerate. Laftly, how would it be poffible to discover and to fubject to controul the various noftrums, quack-medicines, cheats, neglects, and other monsters of

The

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