the space between the two bottoms, is extended to a convenient fpace above the top of the barrel. The fea-water is poured into this tube, and preffing in all directions, according to its altitude, endeavours to force its way through the fand to the top of the barrel, from whence it is drawn off pure. The faline particles being heavier than those of the fand, and perhaps differently formed, are intercepted and left behind, while the water is admitted. Somewhat upon the fame principle, I would explain why fresh-water fpings are got at within 20 yards, or lefs of the fea, as happens at Bermudas, where they rife and fall, with the flood and ebb; yet often there, by digging two or three fet deeeper, falt-water iffues forth. Furthermore, we know, that pump-water, in fea-port towns, is much less brackifh than the fea, though evidently derived from it.'

We presume that this is only an introduction to fome farther account of different waters. We fhall receive our author's future labours with pleasure; for his diligence, his attention, and the extent of his information, deserve our commendation. He seems to wish that the principal fprings throughout this kingdom were analyzed by authority,' as a matter of public concern; and, under so noble a patronage he would feel, he tells us, the strongest inducement to make a tender of his services. A great part of this task is already accomplished; but we could wifh the whole were finished by our author, or some other accomplished chemist.

Appendix or Supplement to Dr. D. Monro's Treatife on Medical and Pharmaceutical Chemistry, and the Materia Medica. Vol. IV. 8vo. 6s. Boards. Cadell.

WE find it difficult to speak or to be filent upon this subject.

When we told Dr. Monro of the imperfection of his first treatife, he was angry, but prudently (cum ratione infaniens) published a short appendix, in which we were treated with little ceremony for fuggefting errors which he corrected, and pointing out deficiencies which he in part fupplied. We then fhowed him that he was ftill deficient and incorrect; but without stepping beyond the bounds of his short appendix, we pointed out the errors we found in it. We trufted that our conteft was at an end a little reflection, we hoped, would show Dr. Monro that we had not maliciously attacked him, that we had not exaggerated the imperfections which we found, nor added unneceffarily to our lift of defects: his own Supplement showed that he had difcovered others. A fourth volume is now published, in which his abufe is again circulated, and he fortunately has enlarged his Supplement to fhow, that our reprehenfion was deferved. But let us hear his own apology:

• After

• After the author's treatife on Medical and Pharmaceutical Chymistry had been printed in the year 1787, the French Nomenclature containing a plan of a new fyftem of chymistry, arrived in this country. At first, most of the ingenious men converfant in pneumatical chemistry, who had long fupported the doctrine of phlogifton, fufpected that mistakes had been committed, in performing many of the experiments brought in fupport of the new doctrine, and that falfe conclufions had been drawn from others; and therefore the author, in his preface, took no further notice of this French work, than in mentioning, that it promised to add great improvements to chymistry; thinking that it would not be right in him to enter into the defcription of a fyftem, the principles of which were not established, and were even fufpected by many ingenious and able men to be erroneous; particularly as at that time it had not been carried fo far, as to point out to us any new or better method of preparing chymical medicines, than thofe already recommended, or to add one new remedy to thofe now in ufe.

But fince that period, many difcoveries have been made by the authors of the new fyftem, which should feem to establish it on a firmer bafis, to enable us to make a more accurate analyfis of bodies than forme ly, and to lead to the difcovery of many chymical preparations, which may prove efficacious remedies in the cure of difeafes; for thefe reafons the author thinks it now right to add to his former work fuch a sketch of the new system, as may give a general idea of ir, and enable those who wish to profecute the study of medical chymistry, to read with more eafe and pleasure the elaborate works of our more modern-chymifts; and, likewise, to add a table, in which the changes produced by chemical operations on fome of the principal fubftances, which are the objects of the foregoing work, are to be accounted for by the new theory."

If we allow that the Treatife' was printed in 1787, it was. published only in 1788, and, unfortunately for this apology.. the new Nomenclature was published early in 1787: the first memoir reached us at the end of June 1787, fufficiently early, if the author had been equally eager for information, to have mentioned it. But, independent of this fact, is the new Nomenclature the foundation of the new theory? Has it even at this moment pointed out any new and better method of preparing chemical medicines, than thofe already in ufe? Has it yet added one new remedy to the lift? In fact, every thing that we reprehended among the omiffions, and fome others which we did not mention, were published long before, or did not depend on the new theory; and we, muft ftill add, that Dr. Monro's ftudies began where they fhould have ended.-But to go on.

The operations performed for eftablishing this new fyftem have already led to the difcovery of a number of preparations, particularly of the faline clafs, which have properties different

from

from those before known; thus the fame acid has different properties, according as its acid fiable bafis is more or less impregnated with the bafis of pure air called oxigene, by our modern French chymifts; and the neutral falts, made with the fame acids and alkaline substances, differ likewife from one another, if the different oxigenation be different in the acids employed thus the neutral falt made with the vegetable alka li and the common muriatic acid, differs very much from that made with the fame alkali in a cauftic ftate, and the muriatic acid highly oxigenated, i. e. impregnated with pure air: the taste of this last falt differs from that of the former, and it detonates when laid on the red hot coal, more strongly than nitre, which the other does not.'

We are forry ftill to contend; but Berthollet's account of the dephlogisticated spirit of falt was published two years before the new Nomenclature; the volatile fulphureous fpirit of vitriol was described many years fince; the difference between fal polycrest and vitriolated tartar was known and explained by Macquer, and the peculiar nature of corrofive fublimate by Scopoli, many years previous to the appearance of the new Nomenclature, Have we not reason then to repeat that Dr. Monro is a young student in the fchool of the new chemifts? We fhall, perhaps, find him not clearly converfant with the others, for fince he chufes to republish his attack, it is neceffary for us to show that he has deferved it.

As Dr. Monro obferves in his reply, that he has confidered only those parts of chemistry which are fubfervient to pharmacy, it is remarkable that he should now treat of fire, not according to the new fyftem, but the older authors. Analyfis, he remarks, was fuppofed to end when bodies were divided into water, falts, oil, and earths. Yet Stahl, to whom Dr. Monro has compelled us to have recourse, obferves, that we cannot arrive at the real principles, or obtain them in a pure state, unless in the form of vapour (Fundamenta Chemiæ, part I. p. 8.) Our author's account of fire is throughout unchemical, confonant neither to the old nor new fyftem, and illogical in a high degree. In the account of heat, there is equal incorrectness, by not diftinguishing between fenfible and specific heat. We might say, in our turn, that ice is not colder than water in a natural state,' for water will long remain at the heat of 32° without freezing, and the cold of ice is not higher; for water, at this time, refifts the action of cold, till it has loft its latent heat, and its air. One fact we must admit, and we cannot contend, when our author gravely tells us, that hog's-lard melts more easily than iron. As he has informed us that his lectures are defigned for pharmaceutical purposes, we suppose he was VOL. LXX. Auguft, 1790. appre

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apprehenfive the student might put the materials for an oint ment into a reverbatory furnace.

Dr. Monro next treats of the doctrine of phlogifton, which he attributes very properly to Becher, and his difciple Stahl. But he tells us that it was illuftrated in the Fundamenta Chemiæ, published at Nuremberg in 1723. This doctrine it will be difficult to find, we believe, in that work, which was published by one of his disciples, at least it does not occur in more than one place in the edition in our hands. The most copious, account of it, by Stahl, is in his Chemical Opufcula, published by himself in 1715, and in one paffage, he feems to apologise for having concealed the doctrine of phlogiston, and Becher's ftrongest arguments in his former publications. If Dr. Monro can produce the paffage which he has quoted, he will for the first time convict us of an error: if he does not, he must remain convicted of having copied from a copy, while he pretends to have read the original. A fufficiently accurate account of M. Lavoifier's fyftem, and the new Nomenclature, follows. We muft obferve, however, in our author's words, before he found out the numerous defects of his fyftem, that as none of these curious enquiries and experiments have been applied to the purpofes of medicine, he looked on them as foreign to his prefent purpose.'-If they were foreign at that time, they are fo ftill, and he must allow that his work was defective formerly, or that it is redundant now. But, in reality, these were not the defects that he was accused of. He puts a piece of new cloth on an old garment, but he puts it where there was no rent. It is to be hoped that another edition will enable Dr. Monro to combine the fhort Appendix and the Supplement in their proper places; but it will never add to his credit to be informed that the materials of each were published before his work.

Our author proceeds to give fome account of vegetable and animal fubftances, and he feems to have tranfcribed with fufficient accuracy from fome able authors. The difficulty, however, which he feels in reconciling the analysis of charcoal in the experiments M. Lavoifier and Metherie, might have been leffened if Dr. Priestley's experiments had occurred to his recollection +. At the conclufion, in p. 2o1, he adds, fuch are the outlines of the new chemical fyftem laid down by M. M. Lavoisier, Morveau, de Fourcroy, and Berthollet, which was first made known to the world, in a work entitled, The New Chemical Nomenclature, which was published in the year 1787.'

Norimberga, 1746 and 7. The preface, by a fcholar of Stahl, is dated 1720, and the lectures are faid to have been copied, ' ante aliquot luftra.' The paffage alluded to is in part III p. 25..

↑ It appears from p. 219, that he was acquainted with them.

It

It is impoffible to accumulate more errors and mifreprefentations in fo fhort a compafs. The new theory was not published in the account of the new Nomenclature. The greater part of

what preceded does not confift of this new theory, but extracts from the experiments of Margraaf, Vogel, Beccaria, and Parmentier; and our author, fo far from giving the outlines of this fyftem, has only given an imperfect outline of one part. We may add too, that of these 150 pages, fcarcely two are fubfervient to pharmacy, the great object of our author.

When Dr. Monro proceeds to the application of the new theory to the different parts of his former work, he comes nearer to his subject. He contends, however, that the particular properties of the falts, prepared with the volatile and the common vitriolic acid, have not been examined. So far as fal polycreft, or the fulphureous falt of Stahl differs from vitriolated tartar, these properties are known. In the other parts of this pretended application, we find our author has contrived to fupply his defects, fometimes at the risk of detection, particularly where he mentions the discovery of the fedative falt in the mineral waters of Tuscany as a late one it was at least mentioned in Bergman's Sciagraphia, published in England in 1783. The difcuffion concerning the nature of different vegetable acids, and the cause of their apparent diverfity, might have been fuppreffed, when the new doctrine had really elucidated the fubject under the title of the Application of the New Theoroy,' it was fomewhat remarkable to find a fubject left in ob. fcurity which that theory would have contributed to explain. We own our obligations, however, to Dr. Monro, for bringing one fubject to our recollection, which we had formerly intended to give an account of, viz. M. Thouvenel's Analysis of Cantharides: we fhall now employ his own words. His language is, in general, fufficiently clear; though we can seldom ftyle it elegant.

M. Fourcroy, in his Leçons Elémentaires, tells us that M. Thouvenel analyfed the cantharides, and found that one half of the dried infect confifted of the vifcera (un parenchy ma) which he did not examine; thar an ounce of the other part yielded three drams of an extractive yellow reddish matter, which afforded an acid by diftillation, twelve grains of a yellow waxy matter, that gives colour to the flies, and fixty grains of a green oily matter, analogous to wax, which smells of the cantharides, and has a fharp tafte; and, if distilled, yields a sharp, acid and a concrete oil like wax.

Water diffolves the yellow extractive matter, the yellow oil, and even part of the green; but æther only diffolves this Jaft, and may be employed to feparate, from the other matters,

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this