a

7

Congela- and in it he observed, that the mercury in the appara- ments, but filled a gallipot made of flint stone (as be- Congelation. tus thermometer, after standing at 42 and 41, for a ing thinner than the common sort), containing about tion.

considerable time, fell to 77, not gradually, but at once an ounce, balf full of quicksilver, into which he in-
as a weight falls.

serted a mercurial thermometer, employing another
In the fifth experiment the weather was excessively as an index. Thus he hoped to determine exactly
severe, so that it ought to have frozen ile metal in the when the quicksilver was congealed, as he had free
open air; but this did not then happen.

access to it at all times, which was not the case when At the time of making the sixth experiment, the it was inclosed in the cylindrical glass, the worsted quicksilver in the open air stood at 44 below o; and wound round the tube of the thermometer to exclude Mr Hutchins resolved to make use of this opportunity the air being equally effectual in excluding any instruto observe how far it was possible to make it descend ment from being introduced to touch the quicksilver. by means of cold, observing the degrees at the same He then made a kind of skewer, with a flat blunt time with a spirit thermometer made by Nairne and point, of dried cedar-wood, on account of its lightness, Blount, with which he had been furnished by the which he found would remain in the gelatinous freezRoyal Society in 1774. In this, however, he did not ing mixture at any depth he chose ; but, when insertsucceed; for the mercury never fell below 438, nor ed into the quicksilver, the great difference betwixt the standard 48. It stood at 27at the beginning the specific gravity of it and that ponderous fluid, made of the experiment. The reason of this was supposed it always rebound upward ; and by the degree of resistto be, that the atmosphere was too cold for making ance, he could always know whether it proceeded from this kind of experiment, by reason of its freezing the fluid or solid metal. At this time, however, the exthread of quicksilver in the stem of the thermometer, periment did not succeed; but, at another trial, havso that it became incapable of contraction along with ing employed about #ths of a pound of metal, and let that in the bulb. In other experiments, though the it remain a considerable time immersed in the same metal in the bulb became solid, yet that in the stem mixture which had just now been supposed to fail, he always remained fluid ; and thus was enabled to sub- found that part of it was congealed; and, on pouring side to a great degree by the diminution of bulk in off the fluid part, no less than two-thirds remained fixed the solid mercury. That this was really the case, ap- at the bottom. peared from the quicksilver falling at once from -86 The last experiment which has been published con- Mr Caveeto –434, when the cold of the freezing mixture di- cerning the congelation of quicksilver by means of dish's exminished, and the tenperature of the air becoming snow, is that of Mr Cavendish, and of wbich he gives periments about the same time somewhat milder, melted the con- an account in the Phil. Transact. vol. lxxiii. p. 325. gealed part in the stem, wbich thus had liberty to de- Here, speaking of the cold of freezing mixtures, he scend to that point.

says, “ There is the utmost reason to think that Mr In this experiment, also, the mixtures were made in Hutchins would have obtained a greater degree of cold double quantity to those of the former ; these being by using a weaker nitrous acid than he did. I found only in common tumblers, but the mixtures for this

(says he) by adding snow gradually to some of this experiment in pint basons. It was observed that they acid, that the addition of a small quantity produced liquefied faster than in other experiments. He had usu- heat instead of cold; and it was not until so much was ally made them of the consistence of pap; but though added as to increase the heat from 28 to 51°, that be added snow at different times, it had very little the addition of more snow began to produce cold; the effect in augmenting the cold, but rather decreased it. quantity of snow required for this purpose being pret- . The congealed piece of the metal fell to the bottom, a3 ty exactly one quarter of the weight of the spirit of might naturally have been expected from its great con- nitre; and the heat of the snow, and air of the room, traction in becoming solid.

as well as of the acid, being 28o. The reason of this From this experiment Mr Hutchins concluded, that is, that a great deal of heat is produced by mixing wathe nearer the temperature of the atmosphere ap- ter with spirit of nitre; and the stronger the spirit is, proached to the congealing point of mercury (so that the greater is the heat produced. Now it appears, a great degree of cold might be communicated to the

from this experiment, that before the acid was dibulb of a thermometer, and yet the quicksilver in the luted, the heat produced by its union with the watube remain fluid), he might make the experiment of ter formed from the melting snow, was greater than ascertaining the greatest contraction of mercury to the cold produced by the same ; and it was not unmore advantage. With this view he made another ex- til it was diluted by the addition of one quarter of periment, when the temperature of some of his ther. its weight of that substance, that the cold, generated mometers stood as low as –37°: and after an hour's by the latter cause, began to exceed the heat generated attendance, he perceived the mercury had fallen to by the former. From what has been said, it is evi1367; but the thermometer unluckily was broken, dent, that a freezing mixture made with undiluted and its bulb thrown away with the mixture. Profes- acid will not begin to generate cold until so much sor Braun bad likewise observed, that his thermometers snow is dissolved as to increase its heat from 28 to 51°; were always broken when the mercury descended be. so that no greater cold will be produced than would low боо.

be obtained by mixing the diluted acid beated to 51° The eighth experiment was made with a view to with snow of the heat of 28°. This method of addtry whether quicksilver would congeal when in con- ing snow gradually is much the best way I koos of tact with the freezing mixture. For this purpose, he finding what strength it ought to be of, in order to did not use the apparatus provided for other experi- produce the greatest effect possible. By means of this

t100.

tion.

a

Congela. acid diluted in the above-mentioned proportion, I froze ferent parts of her Asiatic dominions, and to inquire Congela

quicksilver in the thermometer called G (A) by Mr into the communication betwixt Asia and America,
Hutchins, on the 26th of February 1782. I did not These were Dr John George Gmelin, in the depart-
indeed break the thermometer to examine the state of ment of natural history and chemistry; M. Gerard
the quicksilver therein ; for, as it sunk to 110°, it Frederic Muller, as general historiographer; and M.
certainly must have been in part frozen; but immedi. Louis de l'Isle de la Croyere, for the department of
ately took it out, and put the spirit thermometer in astronomy; draughtsmen and other proper assistants
its room, in order to find the cold of the mixture. It being appointed to attend them. They departed from
sunk only to -30°; but by making allowance of the Petersburgh in 1733 ; and such as survived did not re-
spirit in the tube being not so cold as that in the ball, turn till ten years alter. The thermometrical observa-
it appears, that if it had not been for this cause, it tions were communicated by Professor Gmelin, who
would have sunk to -35° (B); which is 6° below the first published them in his Flora Sibirica, and after-
point of freezing, and is within one degree of as great wards more fully in the Journal of his Travels. An ab-
a cold as that produced by Mr Hutchins.

stract of them was likewise inserted in the Petersburghi
“ In this experiment the thermometer G sunk very

Commentaries for the years 1756 and 1765, taken, rapidly; and as far as I could perceive, without stop- after the professor's death, from his original dispatches ping at any intermediate point till it came to the above- in possession of the Imperial academy, mentioned' degree of -110°, where it stuck. The In the winter of 1734 and 1735, Mr Gmelin being materials used in making the mixture were previously at Yeneseisk in 5810 N. Lat. and 92° E. Long. from cooled, by means of salt and snow, to near o; and. Greenwich, first observed such a descent of the mercuthe temperature of the air was between 20° and 25°; ry, as we know must have been attended with congethe quantity of acid used was 41 oz.; and the glass in lation. " Here (says he) we first experienced the Excessive which the mixture was made, was surrounded with truth of what various travellers have related with re-cold of Si

beria.
wool, and placed in a wooden box, to prevent its losing spect to the extreme cold of Siberia ; for, about the
its cold so fast as it would otherwise have done. Some middle of December, such severe weather set in, as we
weeks before this I made a freezing mixture with some were sure had never been known in our time at Pe-
spirit of nitre much stronger than that used in the fore- tersburgh. The air seemed as if it were frozen, with
going experiment, though not quite so strong as the un- the appearance of a fog, which did not suffer the smoke
diluted acid, in which the cold was less intense by 45°. to ascend as it issued from the chimneys. Birds
It is true the temper of the air was much less cold, fell down out of the air as dead, and froze immediate-
namely 35°, but the spirit of nitre was at least as cold, ly, unless they were brought into a room.
and the snow not much less so.

Whenever the door was opened, a fog suddenly form-
“ The cold produced by mixing sulphuric acid, pro- ed round it. During the day, short as it was, parle-
perly diluted with snow, is not so great as that produ- lia and haloes round the sun were frequently seen; and
ced by spirit of nitre, though it does not differ from it in the night mock-moons, and haloes about the noon.
by so much as 8°; for a freezing mixture prepared Finally, our thermometer, not subject to the same de-
with diluted sulphuric acid, whose specific gravity, at ception as the senses, left us no doubt of the excessive
60° of heat, was 1,5642, sunk in the thermometer G cold; for the quicksilver in it was reduced on the 15th
to —37°, the experiment being tried at the same time, of January o. S. to — 1 20° of Fahrenheit's scale, low-
and with the same precautions as the foregoing. It er than it bad ever hitherto 'been observed in na-
was previously found, by adding snow gradually to some ture."
of this acid, as was done by the nitrous acid, that it was The next instance of congelation happened at Ya.
a little, but not much stronger, than it ought to be, in kutsk, in N. Lat. 62. and E. Long. 130. The wea-
order to produce the greatest effect."

ther here was unusually mild for the climate, yet the
The experiment made by Mr Walker, in which he thermometer fell to 72°; and one person informed
congealed quicksilver by means of nitric acid and the professor by a note, that the mercury in his baro-
Glauber's salt, without any snow, concludes the histo- meter was frozen. He bastened immediately to his
ry of the artiscial congelation of mercury. It now bouse to behold such a surprising phenomenon ; but
remains that we say something of the congelation of it though he was witness to the fact, the prejudice he en-
by the natural cold of the atmosphere.

tertained against the possibility of the congelation, Dr Blagden, from whose paper in the Philosophical would not allow him io believe it. " Not feeling Congelation of

Transactions, vol. Ixxiii. this account is taken, observes, (says be), by the way, the same effects of cold as I quicksilver that it was not till near the year 1730 that thermo- had experienced at other times in less distances, I beby natural meters were made with any degree of accuracy; and gan before my arrival, to entertain suspicions about cold.

in four or five years after this, the first observations the congelation of his quicksilver. In fact, I saw that
were made which prove the freezing of quicksilver. it did not continue in one column, but was divided in
On the accession of the empress Anne Ivanouna to the different places as into little cylinders, which ap-
throne of Russia, three professors of the Imperial peared frozen ; and, in some of these divisions between
academy were chosen to explore and describe the dif- the quicksilver, I perceived like the appearance of frozen

moisture.

warm

a

(A) This was a small mercurial thermometer, made by Nairne and Blount, on an ivory scale, divided at
every five degrees, and reaching from 215° above to 250° below the cipher.

(B) This is to be understood of a spirit thermometer, whose -29°40 of Fahrenheit's mercurial.

tion.

tion.

ments of

Congela, moisture. It immediately occurred to me, that the noon, I found that the mercury had entirely subsided Congela

mercury might have been cleaned with vinegar and into the ball, though it was standing as high as -61° by salt, and not sufficiently dried. The person acknow

The person acknow- at 11 o'clock, and the scale reached down to 238° beledged it had been purified in that manner. This same low 0." On bringing the instrument near a fire, it quicksilver, taken out of the barometer, and well presently rose to its usual height; and the reason of its dried, would not freeze again, though exposed to a subsiding before was its being somewhat warmed by much greater degree of cold, as shown by the thermo- the rays of the sun ; which, feeble as they were, had meter.”

yet suflicient power to melt the small thread of con-
Another set of observations, in the course of which gealed mercury in the stem of the thermometer, and
the mercury frequently congealed, were made by Pro- allow it to subside along with the rest. Mr Hellant,
fessor Gmelin at Kirenga fort in 57 N. Lat. 108. however, so little understood the nature of this pheno-
E. Long. ; his thermometer, at different times, stand- menon, that he frequently attempted to repeat it by
ing at 108°, -86°, --100°, -113', and many o- bringing the thermometer near a fire, when the cold
ther intermediate degrees. This happened in the win. was only a few degrees below the freezing point of
ter of 1737 and 1738. On the 247;h of November, water, but could never succeed until it fell to -589,
after the thermometer bad been standing for two days or lower, that is, until the cold was sufficiently intense
at -46°, he found it sunk at noon to 108°. Suspect to congeal the metal

. The only seeming difficulty in
---
ing some mistake, after he bad noted down the obser- his whole account is, that when the mercury had sub-
vation, he instantly ran back, and found it at 102°; sided entirely into the ball of the thermometer, ą va-
but ascending with such rapidity, that in the space of 'cuum or empty spot appeared, which run round the
half an hour it had risen to 19o. This phenome- cavity like an air bubble, on turning the instrument;
non, which appeared on surprising, undoubtedly de- but this proceeded from a partial liquefaction of the
pended on the expansion of the mercury frozen in the mercury, which must necessarily melt first on the out-
bulb of the thermometer, and which now melting, side, and thus exhibit the appearance just mentioned.
forced upwards the small thread in the stem.

The most remarkable congelation of mercury, which Remark-
A similar appearance was observed at the same fort has ever yet been observed, was that related by Drable esperi-
a few days after ; and on the 29th of December, 0. S. Peter Simon Pallas, who had been sent by the empress

Dr Pallas.
he found the mercury, which had been standing at of Russia, with some other gentlemen, on an expedition
--40° in the morning, sunk to 100° at foar in the similar to that of Dr Gmelin. He did not, liowever,
afternoon: At this time, he says, he “ saw some air spend the winters in which he was in Siberia in the
in the thermometer separating the quicksilver for the coldest parts of that country; that is, about the middle
space of about six degrees." He had taken notice of of the northern part. Twice indeed he resided at
a similar appearance the preceding evening, excepting Krasnoyarsk, in N. Lat. 56, E. Long. 93°; where,

°
that the air, as he supposed it to be, was not then col- in the year 1772, he had an opportunity of observing
lected into one place, but lay scattered in several. the phenomenon we speak of. “ The wintes (says

These appearances undoubtedly proceeded from a hie) set in early this year, and was felt with uncommon
congelation of the mercury, though the prejudice en- everity in December. On the 6th and 7th of that
tertained against the possibility of this phenomenon month happened the greatest cold I have ever experi-
would not allow the professor even to inquire into it at enced in Siberia ; the air was calm at the time, and
all. Several other observations were made ; some of seemingly thickened ; so that, though the sky was in
which were lost, and the rest contain no farther infor- other respects clear, the sun appeared as through a
mation.

fog. I had only one small thermometer left, in which The second instance where a natural congelation of the scale went no lower than -7°; and on the 6th in mercury has certainly been observed, is recorded in the

the morning, I remarked that the quicksilver in it Transactions of the Royal Academy of Sciences at sunk into the ball, except some small columns which Stockbolm. The weather, in January 1760, was re- stuck fast in the tube. When the ball of the thermomarkably cold in Lapland ; so that on the 5th of that meter, as it hung in the open air, was warnied by month, the thermometers fell to –76°, -128o, being touched with the finger, the quicksilver rose ; lower; on the 23d and following days they fell to and it could plainly be seen that the solid columns --589, -79', -92°, and below —238° entirely into stuck and resisted a good while, and were at length the ball. This was observed at Tornea, Sombio, Ja- pushed upward with a sort of violence. In the mean kasierf, and Utsioki, four places in Lapland, situated time I placed upon the gallery, on the north side of betireen the 65th and 781h degrees of N. Lat. and the my house, about a quarter of a pound of clean and dry 21st and 28th of E. Long. The person who observed quicksilver in an open bowl. Within an hour I found them was M. Andrew Hellant, who makes the fol- the edges and surface of it frozen solid, and some milowing remarks, of themselves sufficient to show nutes afterwards the whole was condensed by the natuthat the quicksilver was frozen. “ During the cold ral cold into a soft mass very much like tin. While weather at Sombio (says he), as it was clear sunshine, the inner part was still fluid, the frozen surface exhithough scarcely the whole body of the sun appeared bited a great variety of branched wrinkles; but in ge

. above the low woods that covered our horizon, I took neral it remained pretty smooth in freezing, as did al. a thermometer which was banging before in the shade, so a larger quantity which I afterwards exposed to the and exposed it to the rising sun about eleven in the cold. The congealed mercury was more flexible than forenoon, to see whether when that luminary was so lead; and on being hent short, it was found more low, it would have any effect upon the instrument. brittle than tin ; and when bammered out tbin, it But to my great surprise, upon looking at it about seemed somewhat granulated. If the hanımer bad not

a

or

a

low O ;

23

Congela. the above-mentioned law, so that the new formed ice five or six degrees below the point of freezing quick. Congela tion. and remaining water will be warmed, and must con- silver. In the first experiment also, it sunk to 4480

lion. tinue to receive heat by the freezing of fresh portions at a time when the cold of the mixture was only 2 of water, till it is beated exactly to the freezing point, below that point; so that it appears that the contrac. unless the water could become quite solid before a suf. tion of quicksilver by freezing must be at least equal ficient quantity of heat was generated to raise it to to its expansion by 404 degrees of heat (C). This, that point, which is not be case : and it is evident, however, is not the whole contraction that it suffers ; that it cannot be heated above the freezing point: for for it appears, by an extract from a meteorological as snon as it comes thereto, no more water will freeze, journal kept by Mr Hutchins at Albany fort, that his and consequently no more heat will be generated.- thermometer once sunk to 490° below o; though it The reason why the ice spreads all over the water, in- was known by a spirit thermometer that the cold stead of forming a solid lump in one part, is, that, as scarcely exceeded the point of freezing quicksilver. soon as any small portion of ice is formed, the water There are two experiments also of Professor Braun, in contact with it will be so much warmed as to be pre- in which the thermometer sunk to 544 and 556° bevented from freezing, but the water at a little distance

which is the greatest descent be ever obfrom it will still be below the freezing point, and will served without the ball being cracked. It is not consequently begin to freeze.

indeed known bory cold bis mixtures were ; but from “ Were it not for this generation of heat, the whole Mr Hutchins's experiments, there is great reason to of any quantity of water would freeze as soon as the think they could not be many degrees below 40°. If process of congelation began; and in like manner the so, the contraction which quicksilver suffers in freezing, cold is generated by the melting of ice ; which is the is not much less than its expansion by 500° or $10° of cause of the long time required to thaw ice and snow. beat, that is, almost a's of its whole bulk ; and in all It was formerly found that, by adding snow to warm probability is never much more than that, though it water, and stirring it about until all was melted, the is probable that this contraction is not always deterwater was as much cooled as it would bave been by minate; for a considerable variation may frequently the addition of the same quantity of water rather be observed in the specific gravity of the same piece of more than 150° colder than the snow; or, in other metal cast different times over; and almost all cast mewords, somewhat more than 150° of cold are genera- tals become heavier by hammering. Mr Cavendish ob- Variation ted by the thawing of the snow; and there is great served, that on casting the same piece of tin three of the der.. reason to believe that just as much heat is produced by times over, its density varied from 7.252 to 7.294, sity of methe freezing of water. The cold generated in the ex- though there was great reason to think that no hol tals by freperiment just mentioned was the same whether ice or lows were left in it, and that only a small part of this quest cast. snow was used.

difference could proceed from the error of the experiOn metals

“ A thermometer kept in melted tin or lead till ment. This variation of density is as much as is prowhen be. ginning to

duced in quicksilver by an alteration of 66° of beat:
they become solid, remains perfectly stationary from
turn solid. the time the metal begins to harden round the sides of and it is not unlikely, that the descent of a thermome-

the pot till it is entirely solid: but it cannot be per. ter, on account of the contraction of the quicksilver in
ceived at all to sink below that point, and rise up to its ball by freezing, may vary as much in different
it when the metal begins to harden. It is not unlike- trials, though the whole mass of quicksilver is frozen
ly, however, that the great difference of heat between without any vacuities.

24
the air and melted metal might prevent this effect from “ The cold produced by mixing spirit of nitre of freezing
taking place; so that though it was not perceived in with snow is entirely owing to the melting of the mixtures.
these experiments, it is not unlikely that those metals, snow. Now, in all probability, there is a certain de-
as well as water and quicksilver, may bear being cool gree of cold, in which the spirit of nitre, so far from
ed a little below the freezing or hardening point (for dissolving snow, will yield part of its own water, and
the hardening of melted metals, and freezing of water, suffer that to freeze, as is the case with solutions of
seems exactly the same process), without beginning to common salt; so that if the cold of the materials be-
lose their fluidity.

fore mixing is equal to this, no additional cold can be “ The experiments of Mr Hutchins prove, that produced. "If the cold of the materials is less, some quicksilver contracts or diminishes in bulk by freezing, increase of cold will be produced ; but the total cold and that the very low degrees to which the thermo- will be less than in the former case, since the additional meters have been made to sink, is owing to this con- cold cannot be generated without some of the snow traction, and not to the cold having been in any de- being dissolved, and thereby weakening the acid,, and gree equal to that shown by the thermometer. In the making it less able to dissolve more snow; but yet the fourth experiment, one of the thermometers sunk to less the cold of the materials is, the greater will be the 450°, though it appeared by the spirit thermome- additional cold produced. This is conformable to Mr ters, that the cold of the mixture was not more than Hutchins's experiments ; for in the fifth experiment,

in

22

(c) The numbers here given are those shown by the thermometer witbout any correction ; but if a proper al lowance is made for the error of that instrument, it will appear, that the true contraction was 25° less than here set down; and from the manner in which thermometers have been usually adjusted, it is likely that in the 5th: experiment of Mr Hutchins, as well as in those of Professor Braun, the contraction might equally fall short of that by observation.