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Essay III. On Caloric.

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Gases are those bodies which exist | nation have been separated from each in an invisible elastic state, and which other; for, as some bodies require a cannot be reduced to a solid or liquid greater, and others a less degree of state by a reduction of temperature. temperature, to bring them into a state Elasticity is one remarkable property of vapour, it is evident that a separapossessed by bodies in a state of gas tion of this kind may be easily effector vapours. By the application of ed. From this principle, the processes pressure, their volume is considerably of distillation, sublimation, and evareduced; but, upon its removal, they poration, have arisen. Count Rumexpand to their original bulk. It is ford, and Hassenfratz, have made owing to this property, that the vapour some experiments, with a view to deof water has been employed as a me- termine the capacity of boilers best chanical power. If any fluid be heat-suited to evaporate water from a ed in a vessel from which the vapour | given quantity of fuel; and the latter cannot escape, the vessel will soon has stated the comparative results of burst, although formed of the strongest evaporation at different temperatures. metal. The result with regard to the last, is, that it is most economical to keep the liquor up to its boiling point, the greatest quantity being thus evaporated with the least consumption of fuel. It is necessary, however, to observe, that the heat must not be raised too high, as, when this is the case, the vapour carries with it a portion of the fixed body. This has been remarked, even when the most fixed salts have been evaporated from water at a high temperature.

All vapours and gases possess gravity, as they consist of solid matter rarified by caloric; the discovery of the weight of the atmosphere was one of the happy results of philosophical investigation. But there are some bodies which require the most intense heat to convert them into vapour, and others which have not undergone this change these are the earths and metals; although, however, there are some bodies which have not yet been made to assume this form, still it is presumed that they might be rendered volatile, if it were possible to produce a sufficient degree of temperature.

The transition of fluids into vapour, at a temperature inferior to that at which the liquid boils, is much accelerated by passing over their surface a current of air: if a liquid, whilst exposed to heat, has but an imperfect communication with the air, the process of evaporation goes on slowly; if, however, the air be admitted to the surface, a rapid disengagement of vapour ensues. Gay Lussac has made several experiments on this subject. If sulphuric acid, he observes, be poured on nitre, vapours of nitric

As vapours possess elasticity to a very considerable degree, it is obvious that pressure must materially influence their formation. When pressure is applied, it requires a higher degree of temperature to convert liquids into vapour: thus, for example, under the usual atmospheric pressure, water boils at 212 of Fahrenheit; but it undergoes the same change at 180°, when placed under the exhausted re-acid continue to be disengaged for a ceiver of an air-pump. Ether, which requires a temperature of 104° when exposed to the pressure of the atmosphere, rapidly boils at the common temperature of the atmosphere when placed in vacuo. By applying pres-poration, which does not happen if sure to fluids, they may be heated to a the vessel be lightly covered; and if very high temperature: Water has been the cover be removed, vapours almost heated to above 400° in Papin's di- immediately arise, though none apgester, which is a close iron vessel, peared to escape before from the furnished with a valve, on which a small apertures between the vessel regulated weight presses, and retains and the cover. A number of the methe vapour without the risk of burst-tals, too, such as lead, antimony, and ing the vessel.

Another advantage has been taken, of this tendency in bodies to become volatile upon the application of caloric: substances in a state of combi

long time under exposure to the air; but they soon cease, if the air is excluded. If muriate of potash be kept in fusion in an open vessel, there is a considerable loss of weight from eva

bismuth, give fumes at a red heat, in an open crucible, but afford no sublimate in a closed crucible; appearing, therefore, in the one case volatile, in the other fixed. Lastly, water quickly

evaporates at a common temperature if exposed to the air, but cannot be distilled at the same temperature in vessels imperfectly closed. He accounts for these facts, by supposing, that when a liquid passes into vapour at a temperature inferior to the boiling point, it is not counteracted by the pressure of a different elastic fluid, but by the pressure of its own vapour. Bodies, when converted into vapour, absorb a quantity of caloric, which they give out upon being brought into a state of condensation. Although, however, they absorb a very large quantity of heat by assuming the elastic form, there is no indication of an increase of temperature.

By applying different mineral substances to the circumference of a wheel of fine grit, Mr. Wedgwood found that the substance applied became luminous, even in day-light, at the touching part; if the wheel was made to revolve very rapidly, a pure white light was produced. These sparks The last effect of caloric is ignition. exploded gunpowder and inflammable When certain bodies are exposed to gas, and burnt the skin; a proof that great degrees of heat, they emit light, they were actually in a state of igniand are said to be in a state of igni- tion. Various opinions have been tion or incandescence. No chemical entertained with regard to the cause change, however, occurs when they of ignition. Some who have regarded are brought into this state; for when light and caloric as substances in most the caloric which they contain is respects similar, have conceived that emitted, they assume their original during ignition caloric is converted form. Combustion is a process differ- into light; others have supposed that ent from that of ignition. When com- light is a constituent principle of all bustible bodies are exposed to caloric, bodies, and that by the agency of a chemical action takes place; the caloric it is expelled, when bodies are combustible body, by combining with exposed to high temperatures. The one of the principles of atmospheric former supposition appears to be conair, has its form entirely changed, and tradicted by the circumstance of the is no longer combustible. Ignition is rays of light and heat having been produced by the action of caloric separated from each other. If we alone. Chemists have observed, that adopt the latter opinion, there is some the temperature at which the first stage difficulty in explaining the reason why of ignition occurs, is the same in all the emission of light during ignition bodies. Mr. Wedgwood gilded lines does not gradually diminish, and at running across a piece of earthen- length cease, since there must be a ware, and luted it to the end of a tube limited quantity of light in the body which was placed in a heated crucible; which is exposed to caloric. To get by applying the eye to the other extre- over this difficulty, it is supposed, that mity of the tube, no difference of time bodies, in a state of ignition, receive could be perceived in either the gold light, as well as caloric, from those or the earthenware beginning to shine. substances which keep up and augIn a body, which appears in the dark ment their temperature. In the proat a low red heat, no light will be per-duction of ignition by attrition, the ceived during day-light. Sir Isaac Newton calculated, that bodies which assumed a red heat in the dark, corresponded with 635° of Fahrenheit's scale; in full red heat, with 752°; and in ignition, visible in faint day-light with 1000°. Mr. Wedgwood fixed the point of red heat in the dark, at — 1 of his pyrometrical scale, which corresponds with 947° of Fahrenheit; and ignition during day-light, he placed at the commencement of his scale, or 1077°. In the first stage of ignition No. 30.-VOL. III.

same difficulty attends an explanation of the evolution of caloric as of light. It is supposed that the light which does appear, may perhaps be contained in the body, and that it is expelled by the high temperature which the friction or percussion excites. It must, after all, however, be acknowledged, that there are difficulties attending the extrication of light and caloric, which do not admit at present of a satisfactory solution.

ЗА

(To be continued.)

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First Report of the Mission of Huahine.

FIRST REPORT OF THE MISSION AT

HUAHINE.DECEMBER 1819.

WE doubt not that the following article will prove highly interesting to a large proportion of our numerous readers. It cannot but afford pleasure to all who rejoice at the prosperity of Zion:

Ir is nearly eighteen months since, with a view to more extensive usefulness, that the brethren Barff, Davies, Ellis, Nott, Orsmond, Threlkeld, and Williams, who were to form a Missionary station or stations among the Society Islands, removed from Aimeo to Huahine, accompanied by many of the chiefs and people, who, for the purpose of receiving religious instruction, and attending the stated preaching of the word, had been several years residing there.

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some months before, for the benefit of religious instruction, and had formed themselves into a society, to be united with the society at Huahine. The several services at the meeting, excited unusual attention and interest among the people, both on account of their novelty, and the perfect harmony which pervaded the whole. From the report then read by the Secretary, the total amount of subscriptions for Huahine and Tabuaemanu was 3985 bamboos of cocoa-nut oil, 98 pigs, and 95 balls of arrow-root, (a bamboo of oil containing on an average 2 quarts, and a ball of arrow-root 6lbs.) We rejoice in being able to say, that their zeal has not abated; as a proof of which, many have already paid in their subscriptions, although not due till next May. No doubt, many among them subscribe from the influence of example, or a desire to gain the good opinion of their superiors, but with some it is certainly otherwise. Their missionary spirit springs from their attachment to the word of God; and it will, we trust, on that account continue so long as they feel a love to the Saviour, or appreciate the blessing of his salvation.

Shortly after the establishment of the mission at Huahine, Tapa and other chiefs from Raiatea came up to invite some of our number down to their island, to instruct them and their people in the word of God. After a short stay with us, they returned with the brethren Threlkeld and Williams, with their families accompanying them to Raiatea. For the benefit of me- At Fare, the district where we redical assistance, they were soon after side, the preaching of the word has followed by brother and sister Ors- been regularly attended ever since our mond; the latter of whom was in a arrival. For several months past, we few months called to her eternal rest, have also had the pleasure of seeing followed by her infant daughter, our congregation considerably increaswhose birth she survived but a few ed: two of our number have itinehours. On the 6th of October 1818, rated every Sabbath (with few excepwe had the pleasure to witness and tions) to Maeva, Parea, and Mahapu, assist in the formation of an Auxiliary three of the most populous districts in Missionary Society at Huahine, in the island. A congregation of 3 or 400 aid of the Missionary Society in Lon-usually assemble at each of these don. The people in general, and especially the chiefs, appeared to enter fully into its design, and esteemed it an honour to their island to have a Missionary Society connected with it. They were vigilant in preparing their subscriptions, and had most of them collected before the time appointed for the general meeting.

places. Brethren Davies and Barff have different districts: we trust their journey has awakened some to desire the things which make for their everlasting peace.

During the past year, our number of scholars at this place has been considerably augmented; besides which we have a school at Maeva, and anIn May last, we held the first meet- other at Mahapu, under the care of ing of our Society; the principal native teachers, and superintended by Chiefs of Raiatea, Taha, and Bora- those who visit them. We have also bora, were present to witness our pro- a Sunday School at each of the aboveceedings. Contrary winds alone pre- mentioned places, as well as at our vented some of our brethren at Raiatea residence, which we think calculated from uniting with us on this interest- to produce much good among the ing occasion. Most of the natives of children. The improvements in spellTabuaemanu (Sir Charles Sandersing, reading, and knowledge of the Island) had removed to this island catechism, &c. have been encouraging;

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Henpecked Husband.

734

made in cultivation. Many acres around us are enclosed, and stocked with food of various kinds. Useful tools, pit-saws, &c. together with paper and writing utensils, are in great demand among them. The females especially are much improved in their habits and appearance; when they procure a few yards of foreign cloth, it is not, as formerly, carelessly bound round their loins, but made up into a gown, which gives them a much more decent appearance. Our sisters have by every means in their power con

considerable attention has also been | Considerable progress has also been paid to writing and arithmetic. The number of scholars at present, is, at Fare, about 560, and 100 in the Sunday school; at Maeva 300, and 80 children; at Mahapu 250, and 50 children. We have also been enabled to put another portion of the word of God into the hands of the people, an edition of 2000 | copies of the gospel of Matthew, which we finished printing in October last; they were sought with avidity, and received with gratitude by all. The editions of elementary books have likewise been of essential service in the schools and remote districts.tributed to their improvement, and The gospel of Mark is translated, and the Psalms are in hand; several other tracts are also ready for the press.

Brother Nott having translated the gospel of John and the Acts of the Apostles, in order to avail himself of the assistance of Pomare in the revising it, removed to Tahité in July last, where he is still residing. Since brother Nott left us, brethren Barff and Ellis have been under the necessity of removing with their families for several months to Raiatea. The inconvenience of leaving their stations so long, was only overcome by the reluctance felt to relinquish brother Threlkeld's attention at the time of domestic solicitude. On account of the local circumstances of the Missionaries and people, previous to their settlement at their respective stations, none of the natives were baptized: we have, however, had several under preparatory instruction since our establishment here; and on September 12th, we had the happiness to baptize 15 who were considered proper subjects, among whom were Mahine and Hautia, the principal chiefs of the

island. There are also several candidates now under instructions, whom we intend soon to baptize.

We have observed with peculiar pleasure the improvement in the outward condition of the people, and their progress in civilization. Several of them have finished very neatly plastered dwelling-houses, with doors and windows, and are boarding their bed-rooms; many others on the same plan are now building. They have also erected a very strong and capacious place of worship, 90 feet by 60; it is plastered within and without, and they are sawing boards for the floor.

continually at their respective houses they instruct in needle-work so many as they can get to attend, several of whom have made very considerable proficiency.

We cannot conclude our report, without testifying our gratitude to the divine Author of all good, for the mercies we have received since the commencement of the mission here; and we earnestly intreat an interest in the prayers of all who long for the extension of the Redeemer's kingdom among men, that our feeble hands may be strengthened by the mighty God of Jacob, and we enabled, with a single eye to his glory, and a love for immortal souls, perseveringly to hold on till he shall call us from the fields of labour to the abodes of rest. he may make us increasingly diligent, and, if consistent with his will, increasingly successful, is our most earnest desire. (Signed)

MR. EDITOR.

That

CHARLES Barff.
JOHN DAVIES.
WILLIAM ELLIS.

SIR,-You will much oblige a constant reader and admirer of your excellent Magazine, if you will insert in it the following article:

Petersfield, July 16, 1821. I AM a henpecked husband, which I should not mind, but for one thing; my wife does not pay that attention to economy which I could wish, and which is indeed necessary in every situation of life, according to a person's circumstances.

By living in a gentleman's family, she has unhappily acquired habits of extravagance incompatible with her present situation as a tradesman's

Henpecked Husband.

wife. I am not so rich as Croesus, | but I hope, in future, I shall be more on nor am I stingy with what I have, but | my guard, as it had nearly cost me the I wish to have things managed rightly, so as in some measure to make both ends meet, as they call it.