The tourmalin and a veffel of charged glafs hermetically fealed are both excited by heating and cooling. What other properties have they in common?

• Does electrification increase the exhalation of vapours, either from cold or from boiling water? If it do, is the increased exhalation the fame in all ftates of the atmosphere?

• Does not the electric matter pass chiefly on the surfaces of bodies?

Is the action of electrified bodies upon one another more properly an attraction, or a repulfion ?

Would not continued electrification promote putrefaction? In what manner is the mutual repulfion of two bodies electrified negatively performed? Is it by the attraction of the denfer eleâric fluid in the neighbourhood, or by the quantity of it which may be supposed to be accumulated on the furfaces of fuch bodies?

V. Concerning the Power of Charging Electrics.

What is the real operation of conductors in coating electric fubftances?

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Why may not one phial be charged by connecting it with another (while it is charging) as high as if it were charged at the prime conductor? Or by what rule muft the force of thofe different chargings be estimated? To all appearance, two phials charged together, fo as that one of them receives the fire from the other, do not give fo large a fhock, as only one of them charged in the usual way.

What is the maximum of charging a glass jar, with respect to the quantity of its furface, covered by the coating? It is evident that fome jars will difcharge themselves, when only a finall part at the bottom of them is coated, and when the explofion is very inconfiderable.

Endeavour to charge a plate of glass with the coating preffed into actual contact with its surface, by means of heavy weights. Alfo endeavour to excite a plate of glafs in the fame manner. It is pretty certain that, in the usual method of exciting and charging, the real fubftance of the glass is not touched; and though water be attracted by glass, it may only be to a certain distance from it.

VI. Concerning the Electricity of Glass.

Through what thickness of glass will an excited electric, of any given strength, attract and repel light bodies? Is not the fame thickness the limit of charging the glafs with the elec tric fluid ?

Is not a plate of glass contracted in its dimensions by charg ing, the two electricities ftrongly compreffing it, fo as to increafe its specific gravity?

Is the tone of a glass veffel, made in the form of a bell, the fame when it is charged as when it is uncharged? Or would the ringing of it make it more liable to break in those circumftances?

• Does the electric fluid with which glass is charged refide in the pores of the glass, or only on its furface; or rather within the space that is occupied by the power of refraction, i. e. a small space within, and likewife without the surface?

Is the refractive power of glass the fame when it is charged or excited?

How does the different refractive power of glass, or its denfity (which is probably in the fame proportion with its refractive power) affect its property of being excited or charged?

Is there not a confiderable difference in glass when it is new made, and when it has been kept a month or two, both with respect to excitation and charging?

Let glass of every different compofition be tried both with refpect to excitation, and charging. Would it not be found that differences with respect to metallic ingredients, hardness, annealing, continuance in fufion, &c. would influence both the properties; and that, in feveral cafes, the fame circumftance that was favourable to one would be unfavourable to the other?

But

• Glass has hitherto been supposed to be full of the electric fluid, and its impermeability has been accounted for upon the difficulty with which the electric fluid moves in its pores. may we not fuppofe the fubftance of glass to be abfolutely impermeable to electricity, that no foreign electric matter ever so much as enters a fingle pore of it, but lodges wholly on its furface; for inftance, between the point of contact and the real surface, or within the limits of the refractive power that is a little way on both fides the furface. This place is, I think, on many accounts, extremely convenient to difpofe of the electric matter, whether we make it to confift of two fluids, or of Their being kept asunder, if there be two, or its being prevented from getting through, if there be but one, will be. much easier to conceive in this cafe, than upon the fuppofition that the electric fluid can enter and move in the substance of the glass, though it can only enter and move with difficulty, as pinus expreffes it. For, let the motion be ever fo dif ficult, one would think, that this circumftance could only make it move fo much the flower, and that, give the electricity

one.

in the charged plate of glass time enough, and it would, at length, without any external communication, perform the journey to the other fide, whither it has fo ftrong a tendency

to go. Moreover, one would think, that, upon the hypothefis of the admiffion of the electric fluid within the pores of the glafs, when the discharge of a phial was actually made thro the fubftance of the glass, it might be in a filent manner, without breaking the glafs; whereas when the furfaces of the glafs are fuppofed to be violently preffed, and the pores of it not in the leaft entered by any particle of the fluid, or fluids, the impoffibility of the electric charge getting through the glafs is evident, as well as the neceflity of its breaking the glafs, if it do force a passage.

in

VII. Concerning the Effect of Electricity on Animal

Bodies.

Is the fluid on which electricity depends at all concerned of the functions of an animal body? In what manner any is the pulfe of a person electrified quickened, and his perfpira tion increased?

• Does not the air, by being heated in the lungs, communicate an electric virtue to the blood? What connection has this circumftance with the mephitic air which is exhaled from the lungs in great quantities, as well as contained in all the other excrements of the animal body?

May not the increased perspiration of an animal body be greater in a moist atmosphere than in a dry one, there being then more conducting particles in the atmosphere, to act and react upon the effluvia in the pores of the body; on which the copious perfpiration does, probably, in a great measure, depend?

VIII. Concerning the Electricity of the Atmosphere.

In what manner do the clouds become poffeffed of electricity?

• Does the wind in any measure contribute to it?

Is it effected by the gradual heating and cooling of the air? If so, whether is it the heating or the cooling that produces pofitive electricity? Which ever it be, the contrary will probably produce negative electricity. Let the experiment be made by an electrical kite. Mr. Canton.

As thunder generally happens in a fultry state of the air, when it seems replenished with fome fulphureous vapours; may not the electric matter then in the clouds be generated by

the fermentation of fulphureous vapours with mineral or acid vapours in the air. Mr. Price.

Let rain, fnow, and hail be received in infulated veffels, in different states of the atmosphere, to obferve whether they contain any electricity, and in what degree.

May not the void space above the clouds be always octupied with an electricity oppofite to that of the earth? And may not thunder, earthquakes, &c. be occafioned by the rufhing of the electric fluid between them whenever the redundancy in either is exceffive? Is not the aurora borealis, and other electrical meteors, which are remarkably bright and frequent before earthquakes, fome evidence of this?

Is not the earth in a conftant state of moderate electrification, and is not this the caufe of vegetation, exhalation, and other the most important proceffes in nature? These are promoted by increased ele@rification. And it is probable that earthquakes, hurricanes, &c. as well as lightning, are the confequence of too powerful an electricity in the earth.'

We have transcribed these queries and hints, in preference to any other part of the book, becaufe we apprehend they will be of moft general advantage to thofe who are engaged in electrical enquiries, by fhewing them that, though much has been done, there remains yet much unaccomplished. Some of these problems are indeed difficult of folution; but there are many of them which are by no means beyond the reach of experiment.

In part the fifth, our author treats of the conftruction of electrical machines, and the principal parts of an electrical apparatus. Part the fixth contains practical maxims for the use of young electricians. In part the feventh we have a description of the moft entertaining experiments performed by electricity; and in part the eighth we are prefented with feveral new experiments made by the author in the year 1766. Thefe experiments are most of them curious, entertaining, inftructive, and important. In fhort, the whole book is evidently the work of an indefatigable and ingenious philofopher, and is by far the most comprehenfive production on the subject of electricity.

III. Medical Effays and Obfervations. By Charles Biffet, M. D. 8vo. Pr. 5. Dodfley.

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OCTOR Biffet is already known in the republick of letters by his treatife on the Scurvy, and his Effay on the Medical Conftitution of Great Britain. The difeafes particularly confidered in this volume are the bilious fever of the

Weft

Weft Indies, the nervous colic, fymptomatic tetanus, ophthal mia, iliac paflion, dyfuria, St. Vitus's dance, hooping-cough, worms, land-fcurvy, hypochondriac affection, fcorbutic itch, and dropfy of the knee; to which is added, a chapter of chirurgical obfervations. He has also a chapter of physiological enquiries relative to perfpiration, &c. another, containing ob, fervations relative to putrefaction, and the concoction of peccant humours in fevers; another on the West Indian air; and another containing the theory of the periodical fea and landbreezes in hot climates, which laft mentioned chapter begins his book. This philofophical difquifition, and the diseases peculiar to the Weft Indies, not being of general importance, we shall pass them by unnoticed, and proceed to chapter the fixth, containing obfervations and reflections relative to putrefaction, &c. in which the Doctor controverts the prevailing opinion, as he calls it, that certain malignant fevers do wholly result from a putrid fermentation of the circulating juices excited by a putrid ferment; and likewife the notion, which at prefent is fo prevalent, that putrefaction is the chief immediate caufe of moft fevers.' What the prevalent opinion may be in the county of York, we do not pretend to know; but this opinion is far from prevailing in the fouthern part of the kingdom: and with regard to malignant fevers, that they wholly refult from a putrid fermentation, excited by a putrid ferment, it is fo far from being a general opinion, that we do not believe it was ever advanced by any writer of character. That putrid fevers are often infectious, is most certain; and that, in case of infection, the disease is produced by a putrid ferment, is most rational, which is all that authors have afferted. He confeffes, indeed, that the smell of putrid animal fubftances hath sometimes given rise to malignant fevers; in which cafe, he supposes, that the fever was partly excited by a peculiar influence of the effluvia on the olfactory nerves, but chiefly by the inAuence of fympathy or antipathy. If the doctrine of fermentation cannot be admitted for want of demonstration, the Doctor's hypothefis must appear much less admiffible on the fame account. In fupport of his opinion, " In difeafes, fays he, acquired by infection, particularly the fmall-pox and measles, fome particles only of the juices are affimilated to the nature of the infectious miafmata; but were thefe to operate as a putrid ferment, the whole mafs of blood would be alike diftempered; and, in this cafe, no feparation of the peccant humour, or an eruptive crifis, could poffibly take place.' So that, according to this hypothefis, no feparation can take place,, if the whole mafs be affected: the very contrary of which happens to be true in every inftance of fermentation, where the VOL. XXIII. May, 1767. ferment

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