difpute the power: and it is more than probable, that if the more enlightened and rational profeffors of Quakerism were queftioned about the doctrine of the Spirit, they would confefs, that, divefted of its myftical drefs, it in reality means nothing more than a virtuous and Chriftian principle, which determines the mind to fubdue all grofs and irregular affections, and to produce the peaceable fruits of righteoufnefs,'-humility towards God, and juftice and charity to man.

ART. XIII. Experiments and Obfervations on Animal Heat, and the Inflammation of Combustible Bodies. Being an Attempt to refolve these Phenomena into a general Law of Nature. By Adair Crawford, A. M. Svo. 2s. 6d. Murray. 1779*.

T

O one, who confiders the great variety of talents, which are neceffary for the fuccefsful profecution of natural knowledge, it will not appear furprifing, that among the crowds who are daily occupied in philofophical purfuits, we fhould fo feldom meet with a perfon, whofe labours tend in any confiderable degree to the improvement of fcience. In fome branches of literature, the cultivation of one particular endowment of the mind is fufficient to confer diftinction. But in physical and chymical enquiries, a combination of various and rare qualifications is requifite; and the philofopher who afpires to eminence, muft ftudy to unite with an uncommon degree of fagacity and ingenuity, a talent for obfervation, a fcrupulous attention to minute and apparently trifling circumftances, and a dexterity in performing manual operations; accomplishments which are not always connected with the higher gifts of the mind.

The philofophers who have applied themselves to the study of nature, have in general been apt to run into extremes. Before the time of Lord Bacon, facts were almoft entirely overlooked, and the advancement of fcience was attempted by the force of genius alone. It may be queftioned, whether fome of the prefent race of enquirers are not in danger of falling into the oppofite error of accumulating at random, experiments and obfervations, which add to the lumber of fcience, without affifting us in invefligating the laws of nature.

We make thefe remarks, not to introduce a cenfure of the performance before us, but to place its merit in a more advanta geous light, by contrafting it with the common productions of chymical writers. The Author of it has evidently had in view

*Certain circumstances having prevented us from giving fo early an account of this publication as we could have wished, we have willingly adopted the following contribution from an unknown correfpondent; at the end of which, we have thought fit to fubjoin only a few obfervations that occurred to us on the perufal of it; marking by capital letters, the paffages to which our obfervations refer.

that

that perfect model of philofophical enquiry, which Newton has exhibited in his optics.-The experiments which he defcribes, are numerous, and feem to have been made with uncommon industry, and with a proper attention to every circumftance that could be fuppofed to affect their refults. At the fame time, the plan on which he has proceeded, and the inferences which he has deduced from his facts, bear marks of that fagacity and ingenuity, which diftinguish the enlightened and philofophical enquirer from the empirical experimenter. How far his theory is juft, it is impoffible to determine, without a careful repetition of his experiments. In juftice, however, to the Author, we must acknowledge, that he relates them with the appearance of accuracy and candour, and that the reafoning which he founds upon them, seems to be ingenious and confequential.

The firft fection of this Treatife contains fome facts and observations on heat in general.-For the greater part of thefe, Mr. Crawford acknowledges himself indebted to the lectures read in the Universities of Edinburgh and Glasgow, by Dr. Black and Dr. Irvine.-The following abstract will give an idea of their refult.

If equal quantities of the fame fluid, at different temperatures, be mixed intimately together, the temperature of the mixture will be half the excefs of the hotter above the colder. -If, for example, a pint of boiling water, at 212, be mixed with a pint of the fame fluid at 32, the temperature of the mixture will be 122, the warm water will be cooled 90 degrees, and the cold water heated 90 [A].

But if this experiment be made with water and mercury in the fame circumftances, the refult will be different. Thus, if you take equal bulks of mercury and water, and give the water a greater degree of heat than the mercury; the heat of the mixture will always be greater, than half the excefs of the heat of the water above that of the mercury. If, on the other hand, the mercury be hotter than the water, the temperature of the mixture will always be less than half the excefs of the heat of the mercury above that of the water. In general, if equal bulks of water and mercury, at different temperatures, be mixed together, the change produced on the temperature of the mercury, will be to that produced on the temperature of the water, in the proportion of 3 to 2.

In thefe experiments with water and mercury, a quantity of heat is communicated from one fluid to the other: the one gains whatever the other lofes. But the changes produced on their temperatures are different. The fame quantity of heat, which, when communicated to water, produces a change as two, when communicated to mercury produces a change as

three.

three. It appears therefore, that in the cafe of heterogeneous bodies, we can draw no conclufion concerning the comparative quantities of heat taken from them, or added to them, from the changes which take place in their temperatures, as indicated by the thermometer.

This reafoning may be pushed farther. Since the fame quantity of heat produces unequal changes on the temperatures of different bodies, it follows, that two bodies which are at the fame temperature, may contain unequal quantities of abfolute heat. Thus, when water and mercury are at the fame temperature, the water contains a greater degree of heat than the mercury. For, fuppofe a pint of mercury and a pint of water to be both deprived wholly of their heat: fince the fame quantity of heat, which, when communicated to water, produces a change in its temperature as two, when communicated to mercury, produces a change in its temperature as three; it follows, that in order to produce equal changes on the temperature of mercury and water, we must communicate to them quantities of heat in the proportion of two to three; and therefore, if they are wholly deprived of heat, we muft, in order to bring them to the fame temperature, communicate to them quantities of heat in the proportion of thefe numbers. Hence it follows, that when a pint of mercury and an equal bulk of water are at the fame temperature, we may conclude, that the quantity of heat in the water is to that in the mercury, in the proportion of three to two. It is proper to obferve, that in the foregoing reafoning, the water and mercury are fuppofed to continue in their fluid form, when deprived of their whole heat.

In order to prevent ambiguity, Mr. Crawford makes a diftinction between the abfolute and fenfible heat of a body [B]. By abfolute heat, he means the whole quantity of heat (or of the element of fire, as fome philofophers have expreffed themselves) which is contained in a body. By fenfible heat, that part of the abfolute heat, which produces the expanfion of the mercury in the thermometer; and which is found partly to depend on the quantity of the abfolute heat, and partly on the nature of the body, in which this heat is contained.

The conclufions deduced from the reafonings contained in this part of the work concerning heat in general, may be comprehended in the following propofitions.

1. Equal weights of heterogeneous fubftances, having the fame temperature, may contain unequal quantities of abfolute

heat.

2. There are, therefore, certain differences in the nature of bodies, in confequence of which, fome have a greater capacity for collecting and containing hear than others.

3. The comparative quantities of abfolute heat in bodies, are reciprocally proportional to the changes which are produced on their fenfible heats, when they are mixed together at different temperatures. It muft, however, be obferved, that this rule does not apply to thofe fubftances, which, in mixture, produce fenfible heat or cold by chymical action.

We thought it neceffary, before giving any account of Mr: Crawford's doctrines concerning animal heat, and the inflammation of combuftible bodies, to take notice of the doctrines contained in his introductory fection, as it is from these that he deduces his method of eftimating the abfolute heat of the different bodies, which are the fubjects of his experiments.

It has been already obferved, that bodies differ from each other, in their capacities for abforbing and retaining heat. From a great variety of experiments, related by Mr. Crawford, it appears, that the capacities of bodies for containing heat are diminished by the addition of phlogifton, and increafed by the feparation of this principle. Thus metals contain lefs abfolute heat than their calces, and fulphur lefs than the vitriolic acid. The calx of antimony, for example, contains nearly three times as much abfolute heat as the regulus. Hence it follows, that if phlogifton be added to a body, a quantity of the abfolute heat of that body will be extricated; and if the phlogiston be feparated again, an equal quantity of heat will be abforbed.

It is a confequence of these experiments, that heat and phlogifton, fo far from being intimately connected, as most philofophers have imagined, act in fome measure in oppofition to each other. By the action of heat on bodies, the force of their attraction to phlogifton is diminished, and by the action of phlogifton a part of their abfolute heat is expelled.

It has been demonftrated by Dr. Priestley, that in refpiration, phlogifton is feparated from the blood, and combined with the air. If therefore it be a general fact, that the feparation of the phlogifton from bodies increafes their capacity for containing heat, and that the addition of it has the contrary effect; it will follow, that in refpiration, a quantity of heat must be difengaged from the air by the union of the air with phlogifton; while, at the fame time, the feparation of the phlogifton from the blood increases its capacity for containing heat, and difpofes it to abforb that portion of it which the air has depofited.

This conclufion is perfectly agreeable to Mr. Crawford's experiments, from which it appears, that atmospherical air contains a greater quantity of abfolute heat, than the air which is expired from the lungs of animals; in particular, that the fixed air which is exhaled by expiration, contains only the fixtyseventh part of the heat which was contained in the atmospherical air, previous to infpiration [C].

From

The darkness of Popery feems greater here than in France; although it may be seen and felt there beyond all expreffion. Oh! the pain and diftrefs of foul I was almoft continually under by the muddy rivers of Babylon in thofe lands of darkness the harp being indeed, as it were, hung upon the willows. No fweet melody nor fong of Sion could be echoed forth (the Lord knoweth) under the power of the king of the bottomlefs pit, who rules in the mystery of iniquity. Yet fo it must remain until that almighty Arm that cut Rahab in pieces, and wounded the dragon*, is pleased to arife, and put on ftrength, that he may turn and overturn: pouring forth the vials of his wrath upon the feat of the beast and false prophet, thereby making the fcarlet whore of Babylon defolate, and burning her fleth with fire, that the nations may no more be intoxicated with the abominations of the wine of her fornications.'

The method in which the Author relates his meeting with Friends in public worship, is generally confined to a few fingular expreffions, fuch as- We had a clofe, roufing time of ita trying laborious meeting-an open and comfortable opportunity-a heavy, afflicting season.' We fhall produce a specimen of the Author's manner of relating the event of a meeting at Sunderland, together with a hint which he throws out to the Friends who are too often inclined to make hearty dinners on first days.

We went to Sunderland, and attended their meetings on firft day. That in the morning was very open and fatisfactory; the teftimony of truth going forth freely to the several states of those persons who were much affected therewith. In the afternoon it was a heavy afflicting meeting: but little felt of that which crowned the meeting in the morning. We often find afternoon meetings are the moft heavy and painful, occafioned,

Our poor Friend meets with this fame dragon, not only in Spain, but in Ireland; and perhaps, where fuch a terrible animal would not have been expected, viz. in a Quaker's meeting: I went, fays he, to Meath-treet [in Dublin] in the morning, where I had thorough fervice to my own great comfort and ease, though my fpirit was much grieved to view the havock made amongst Friends in that great city by undue liberties: but most of all under a mournful fenie, that the dragon's tail had drawn down fome of the flars again into earthly pollution, and caufed a bad favour. This was offenfive to my foul-even as a nuijance in that meeting.'-Exhalans mephitim!This could not be the dragon of the Apocalypfe: for we read nothing of his favour. It must have been the dragon of Wantley,' whole flink, as well as whofe terror, is recorded in the celebrated ballad of the Achievements of More of More-Hall.'

Vid, the DEAN of Carlifle's Collection of the Reliques of

antient Poetry.'

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