bus, the air is lefs falubrious at a certain height, than it is when nearer to the furface of the earth;-and laftly, that in parity of other circumftances, the air is the leaft falubrious in the drieft places. Here we have, at leaft, fome novelties.

The refults of the experiments made in Winter by our Academician, are, 1ft, That be the cold more or lefs intenfe, this difference has no influence on the qualities of the air in one and the fame place, fince the air is of the fame quality in a cold of 3 degrees above, and in one of 10 degrees below o, and the variations which are perceived between the degrees of falubrity in the air, are in no fixed proportion to the variations of its temperature -2dly, That in Winter there is very little difference between the degrees of the phlogistication of the air in different places, and that this latter is nearly the fame in places where, in the Summer-feafon, it would exhibit very confiderable variations.-3dly, That in Winter the air is moft falubrious in thofe places that are the leaft inhabited.-4thly, That in places that are inhabited, the air is not fo good in Winter as in Summer, while in thofe that are uninhabited, or thinly peopled, it is much more falubrious in Winter than in Summer.

Such are the refults of the eudiometrical experiments made with nitrous air; thofe made with inflammable air led to refults not only different from, but totally oppofite to thefe; and the air, which by the former of thefe tefts is proved the fitteft, is by the latter pronounced the least fit, for respiration.-The question then is, to which of thefe eudiometers we are to give credit? M. ACHARD gives it to the former, and founds his conclufions on the trials made with nitrous air. The reafon of this preference, which at least furprize us. Thefe confiderations would naturally lead us to conclude, that in places the moft inhabited the air would be the leaft falubrious, efpecially in Summer;-that it would be the pureft in thofe places which abounded moft with plants and trees, and that in Winter it muft be, generally fpeaking, purer than in Summer, both in places inhabited and uninhabited,-in the former, because cold prevents putrefaction, and in the latter, because by the fufpenfion of vegetation, one of the caufes of the phlogiftication of the atmospherical air is removed.-Our Academician is aware of these difficulties, and has not disguised them; but they neither remove nor diminish the confidence he places in the multiplicity of his experiments, and the juftnefs of the conclufions drawn from them. He feems to think that NATURE has a method of dephlogisticating the atmosphere, which is as yet totally unknown to us; and that this operation always accompanies that by which the air charges itfelf with phlogifton. Several experiments have induced him to conjecture that this operation may be a reforption of the phlogifton, effected by the abforbing veffels of the skin of animals.-He, however, throws out this idea only as a conjecture.

is

is the confequence of careful experimental researches, he promifes to communicate to the public in another Memoir.

Mem. IV. Concerning the Effect produced by the Addition of different Bodies to Water, with respect to the Degree of Heat of which it is fufceptible in Ebullition. By THE SAME. From a long feries of well-conducted experiments, of which the operations and refults are here difplayed in feveral tables, it appears, 1ft, That the fubftances which are not diffolved in the water that is added to them, change the degree of heat which the water receives in ebullition.-2dly, That the degree of heat of which boiling water is fufceptible, when it is pure, and when another fubftance is added to it, varies according to the nature and quantity of the fubftance that is added.-3dly, That the difference in the degree of heat of boiling water, with or without the addition of another fubftance, does not depend upon the immediate contact of that fubftance with the thermometer.-4thly, That the quantity of the fubftance that is added to the water has an influence on the change that enfues, with respect to the degree of heat which the water acquires in ebullition, but that this influence has its bounds, and that there is a certain determinate quantity for every fubftance which produces the maximum of this effect, fo that when this quantity is once added to the water, the addition of a greater quantity has no influence at all.-5th, That there feems to be no kind of connection or proportion between the specific gravity of bodies, and the property they poffefs of diminishing the degree of heat in ebullition.6thly, That the different claffifications of bodies, as animal, vegetable, and mineral, feems to occafion no difference in the property they poffefs of diminishing the degree of heat in boiling water, fince there are in all the three claffes, bodies which produce diminutions equally confiderable.-Laftly, That the more the fubftance added to the water is divided and reduced to fmall parts, the greater is the diminution which it produces in the degree of heat which water affumes in ebullition.

Mem. V. On the Natural Hiftory of the Camphor tree, out of its native Soil, and particularly in the North of Germany. By M. GLEDITSCH. In May 1749, M. GLEDITSCH read to the Academy of Berlin a Memoir concerning the camphor-tree; he prefented, at the fame time, to that learned affembly, a branch of this tree, which had bloffomed in the botanic garden of Berlin, a phenomenon which he announced as the first of the kind that had been obferved in Europe, and of which there is a plate annexed to the prefent Memoir. The natural hiftory here given of the camphor-tree is curious and inftructive.

Mem. VI. and VII. On the Tranfmutation of Earths and Stones, and their Tranfition from one Genus to another. By M. GERHARD.

Part

Part I. and II. In thefe two voluminous and curious Memoirs, the ingenious and acute Academician treats, in a mafterly manner, one of the difficulties that occur in natural hiftory and chymical analyfis. At first fight, the formation of earths and ftones does not feem fuch a difficult fubject of inveftigation. The fe fubftances are remarkable for their fimplicity, as their texture is not organical, and they are not impregnated with any vital powers. Neverthelefs, the operations of Nature in mineral productions are fo flow, and her progreffive fteps are fo imperceptible, that it is extremely difficult to furprize her at the decifive moment when her fecret may be difcovered. The tranfmutation of minerals from one clafs or genus to another, has been maintained and opposed by the most eminent adepts in mineralogy and natural hiftory. This fubject M. GERHARD difcuffes in the prefent Memoir, 1ft, By determining, with precifion, what we are to underftand by the tranfmutation or paffage of earths and ftones from one clafs or genus to another. 2dly, By inquiring whether this tranfmutation is contradicted by experiments, or is incompatible with the principles of natural philofophy and chemistry. 3dly, By weighing the arguments, and examining the facts which feem to prove for or against the exiftence of this operation of Nature. And finally, By fhewing, that the former deferve the preference, and by adding the evidence of new chemical experiments to confirm the reality of this operation,

Mem. VIII. Extract of the Meteorol-gical Obfervations made at Berlin in the Year 1784. By M. BEGUELIN,

MATHEMATICS.

Mem. 1. Theory of the periodical Variations of the Motion of the Planets. Part II. containing a Calculation of Variations, independent on Excentricities and Inclinations for each of the primary Planets. By M. DE LA GRANGE. In the first Part, which was published in the foregoing volume, this learned Academician gave the general formule of the variations here mentioned. In this Second Part we find the numerical application of these formula to all the primary planets, in order to furnish a complete analysis of their perturbations, occafioned by their mutual at tractions.

Mem. II. On Gnomonics, or the Science of Dialling. By M. CASTILLON. The lubftance of this Memoir is the work of the late celebrated M. LAMBERT, which is here published by M. Caftillon, under an improved form, and with additions and remarks, which fhew how the theory and practice of dialling may be reduced to a greater degree of fimplicity.

Mem. III. Concerning Fluids, confidered with relation to HydroDynamics. By the late M. LAMBERT. In this Memoir, which is published by M. John Bernoulli, the learned Author founds the first principles of hydro-dynamics on the elasticity of the particles

of water, to which he adds their tenacity and friction. We muft refer the curious Reader to the Memoir itself, as the details it contains are not susceptible of such an abridgment as would render them intelligible,-and the plates also are necessary for this purpose.

SPECULATIVE PHILOSOPHY.

Mem. I. Confiderations on the First Tufculan of Cicero, concerning Death. By M. FORMEY. There is much more good fenfe and true philofophy in thefe Confiderations, than we have ever found in the Dialogues of Cicero which occafioned them. The high veneration we have for that illuftrious Roman does not dazzle us fo far as to prevent our perceiving the want of method, the contradictions, the puerilities, and fophifms, that form an unpleafing contraft with many fine paffages in this First Tufculan. Certain it is, that M. FORMEY ftates the cafe with much more precision than Cicero has done. If death, fays he, is the final term of our existence, we are no longer either happy or unhappy when it arrives. But if there be another life after this, we may, in this cafe, either hope for happiness, or fear the contrary, in a future ftate. In the former cafe, those who defire to live, or to have their exiftence prolonged, cannot, if they reflect at all, think of death, and its inevitable approach, which renders their exiftence but a tranfitory meteor in the night of eternity, without anxiety and pain. The brute naturally dies, as it has lived, without reflection on the prefent, or anticipation of the future, and confequently with indifference; but man, who has carried to a certain degree of improvement the powers of reafon and the capacity of enjoyment, and is ever cafting his thoughts forward beyond the prefent moment, muft voluntarily place himself in the fphere of the brute, when he beholds death with indifference,-which, if it be real, and not pretended, is rather to be deemed ftupidity than fortitude.— On the conjectural fuppofition of another life after this, a reafonable being ought to adhere to fuch principles, and fuch a line of conduct, as will most probably tend to better his condition in a future fcene. But on every fuppofition, death is an awful thing; and it is not a mark of pufillanimity to think of it with a certain inquietude, as it terminates all our enjoyments, and diffolves all our most interesting connections. The title of the First Tufculan is, Concerning the Contempt of Death; and this fentiment is inculcated into the difciple of Cicero with great fuccefs; yet in this fame Dialogue Cicero tells us, that the life of the WISE man is a continual meditation upon death. Now, it is a very strange kind of wisdom which is perpetually occupied upon an object that is contemptible. According to M. FORMEY, the wife man will think frequently of death, render the idea of it familiar, meet it with a modeft dignity, without thofe indecent pleasantries

"

pleafantries on the one hand (which have been thrown out by
certain pretended great men in their dying moments, and related
by their panegyrifts as redounding to their honour), and alfo
without thofe vain lamentations on the other, which only in-
crease the bitterness and anguish of their departure.'-There is,
furely, fterling fenfe, and found philofophy, in this view of the
fubject,

There are many more judicious obfervations on the subject in
this Memoir, which, however, is employed in feverely criti-
cizing, and often in expofing to ridicule, the reasonings of
Cicero on the immortality of the foul, which are contained in
the First Tufculan. M. FORMEY is prolix and talkative in this'
analyfis, but he is more lively, fmart, and entertaining, than
critics generally are, especially when advanced in years, as he
is. Cicero fays, that he never varied in his belief of the foul's
immortality; but our Academician thinks he did. Socrates and
Cicero were', fays he, in the fame ftate of mind with respect
to this object; they ardently wifhed for immortality, and in cer-
tain moments, entertained a perfuafion of it which they took for
Gonviction; but, at other times, a cloud arofe which obfcured
the profpect. This,' continues he (with more levity and plea-
fantry, than equity and candour), puts me in mind of a learned
courtier, well known to this affembly, and beloved by us all,
who faid, that in fummer he believed the immortality of the foul, but
-Where is the man whofe conviction is
doubted it in winter..
at all times equally clear and unclouded?

Mem. II. Reflections on Games of Hazard. By M. D'ANIERES. Mem. III. On the Diftinctions between COMMON SENSE, JUDGMENT, TASTE, SENTIMENT, WIT, IMAGINATION, GENIUS, and TALENT,-together with fhort Reflections on Eloquence, Style, and Tranflations. By M. SECONDAT. This ingenious writer is the fon of the celebrated Prefident De Montefquieu, and has inherited a portion of his nice penetration and elegant tafte. There is nothing, however, in this Memoir Lufficiently new or interefting to require particular notice. The reflections it contains are fhort, fententious, fometimes juft, frequently plaufible, and now and then obfcure.

BELLES LETTRES.

Mem. I. Concerning the true Wealth of Nations, the Balance of Commerce, and the Balance of Power. By the Count DE HERTZBERG, Minifter of State, and Rector of the Academy. This excellent Differtation has been already reviewed in the English tranflation of it, published by Dr. Towers. See p. 42. of the Review for January 1787.

Mem. II. On the Influence of the Sciences on Poetry. Fifth Memoir. By M. MERIAN. This ample Differtation, which con

6

tains