EBULLITION.
429
tall glass cylinder, standing upon a sand-bath. A column of the heated and lighterParticles will be seen ascending near the axis of the cylinder, surrounded by a hollowcolumn of the cooler ones descending near the sides. That this molecular translationOf locomotion is almost the sole mode in which fluids get heated, may be demonstrateday placing the middle of a pretty long glass tube, nearly filled with water, obliquely0 ' rer an argand flame. The upper half of the liquid will soon boil, but the portion underme middle will continue cool, so that a lump of ice may remain for a considerable time atthe bottom. When the heat is rapidly applied, the liquid is thrown into agitation, inconsequence of elastic vapor being suddenly generated at the bottom of the vessel, andbeing as suddenly condensed at a little distance above it by the surrounding coldcolumns. These alternate expansions and contractions of volume become more manifest? s the liquid becomes hotter, and constitute the simmering vibratory sound whichls the prelude of ebullition. The whole mass being now heated to a pitch compatibleits permanent elasticity, becomes turbulent and explosive under the continuedhnuence of fire, and emitting more or less copious volumes of vapor, is said to°H. Tim further elevation of temperature, by the influence of caloric, becomes“possible in these circumstances with almost all liquids, because the vapor car-tlm ^ l0m l ^ em as muc h heat in a latent state as they are capable of receiving from
temperature at which liquids boil in the open air varies with the degree of atmo-jPheric pressure, being higher as that is increased, and lower as it is diminished. HenceWing water is colder by some degrees in bad weather, or in an elevated situation, withdepressed barometer, than in fine weather, or at the bottom of a coal-pit, when theof r °®eter is elevated. A high column of liquid, also, by resisting the dischargeJojo 6 stean, ij raises the boiling point. In vacuo, all liquids boil at a temperature aboutlower than under the average atmospheric pressure. For a table of elasticities,o r . P0R . Gay Lussac has shown that liquids are converted into vapors more readily,less turbulence, when they are in contact with angular or irregular, thangla smo °th surfaces ; that they therefore boil at a heat 2° F. lower io metallic than in^ v essels, probably owing to the greater polish of the latter. For example, if into
- le r about trk in a rrlacc motroee ii*r»n filinorc crrrmn/l office
P°\vdi
shout to boil in a glass matrass, iron filings, ground glass, or any other insoluble
th f0Wr e !,' >e thrown, such a brisk ebullition will be instantly determined as will sometimest\ j, e ' va ter out of the vessel; the temperature at the same time sinking two degreesc oni>„ . Wou ld thence appear that the power of caloric, like that of electricity, becomesed by points.
totan.,? Uowin S ta ^ e ex bibits the boiling heats, by Fahrenheit’s scale, of the most im-bquids ;—
Eth e ,.
Ca r v’ s Pmfic gravity 0-7365 at 48°
Alc„ h U 7«f sulphur
At:, . u °J, sn. era*, n.
fritHo"" 5 . S ,P- S ra v. 0-813 -
» ^ acid,
%
$ati
ater
1-500 -
5 te( l solution of Glauber salt
do.
do.
do.
do.
do.
do.
do,do.do,do.do.do.
Muriatic
do. do.
Citric acid, do.
do. do.
Rectified petroleum.£>i\ of turpentine
Sulphuric acidj sp» § r *do.
acid > sp. g r . 1*094
Acetate of leadSea salt
Muriate of lime,do.do.do.
do,do.do.do.do.p, do.
&ar»
do.
do.
do.
do.
do.
do.
do.
1-127
1-420
1-30
1-8481-8101-7801-7001-6501-5201-4081-300 -f
UreDalton
Biotdo.do.Ure
1 4- water 2, do.35-5 -j- do. 64-5, do.40-5 -f- do. 59-5, do.
Dalton
do.
do.
do.
Ure
do.
- - Dalton
do.
- - do.
- - do.
do.
do.
do.
do.
do.
do.
do.
100 °
113
173-5
210
212
213|
215#
2241
285
230
235240232222248
236306316600473435374350290260240554570640