The rate of dilatation of liquids is not generally uniform, like that of solids and gases, it increases with increase of temperature ; and as the liquid approaches solidification on the one hand, and the point of vaporisation on the other, other irregularities in its contraction and expansion take place. Water is a most remarkable exception to the law rf expansion by heat and contraction by cold ; it contracts on cooling like other liquids until it reaches the temperature of 4° C. ; when still further heated, it contracts^ so that at 56° its density is the same as it was at 0°, and at 69° still greater ; beyond this temperature, expansion again takes place ; at Sy'g" the alloy has once more the same density as at 0°, and at 94° the same as at 44°. Liquids, like solids and gases, expand when they are heated and contract when they are cooled ; they expand pro- portionately much more rapidly than solids ; they differ also in expansibility to a much greater extent, the most volatile being generally the most expansible.A public domain book is one that was never subject to copyright or whose legal copyright term has expired. All gases, on account of the absence of any cohesive- ness between their particles, expand alike, the pressure being the same for equal additions of heat; the rate of expansion being equal and uniform at all degrees of temperature ; they expand rather more than one-third their volume on being raised from the temperature at which ice melts to that at which water boils at the ordinary atmospheric pressure.
When the surface is frozen, the tempera- ;0 4'' 32 Fundamental Principles of Chemistry lure of the deep water remains at 4° C.
; when this temperature has been reached the surface water ceases to sink, owing to its becoming of less density than the water underneath ; and the lighter water on the top protects that underneath from a further reduction of temperature owing to its bad heat-conducting power i and when it solidifies by further coo Ung, the ice formed remains on the surface, because its density is less than that of the water underneath.
Whether a book is still in copyright varies from country to country, and we can't offer guidance on whether any specific use of any specific book is allowed. The student will observe, from these illustrations, that heat and cold are merely relative terms. would therefore stand — 30X ^^-^ — , or A°T°A inches or 33'92 feet high. From these facts we learn that the pressure of ' atmosphere is capable of supporting a column of merci about 30 inches in height, and a column of water about feet in height ; or, to state it conversely, the pressure of column of mercury of 30 inches, and a column of water of feel, in height is equal to the pressure of the atmosphere. As the pressure of the atmosphere supports a colut of mercury whose base is a square inch 30 inches in heigh and as a cubic inch of mercury weighs, in round numbers, h a pound, 30 cubic inches of the metal will weigh 15 lbs.
Please do not assume that a book's appearance in Google Book Search means it can be used in any manner anywhere in the world. 86i Our sense of touch cannot be employed to ascer Thermoscopic Agents 35 p correct temperature of substances ; for that will only tell us lether the suhstarice has a higher or a lower temperature at ; time than that part of our body which comes in contact Ji it. ; therefore, follows that the pressure of the atmosphere on ea square inch of surface is equal to 15 lbs., and this pressure 15 lbs.
These facts admit of a very simple explanation, ' As the water in the middle portion of the tube growt!
23), ' tube is filled with water, i its middle is surrounded wit Jt a freezing mixture. 76, ' The lower thern HV meter descends steadily t C, and there remains ! The upper thermo- meter at first undergoes veij little change, but when tl ''"■ '*■ lower one has reached tl fixed temperature, the upper one begins to fall, reaches ll temperature of zero, aud, finally, the water at the surface freeze]^ if the action of the frigorific mixture continues for a sufficient^ long time.Maintain attribution Tht Goog Xt "watermark" you see on each file is essential for in forming people about this project and helping them find additional materials through Google Book Search. Keep it legal Whatever your use, remember that you are responsible for ensuring that what you are doing is legal. This imparting of heat by the one body, and the receiving of it by the other, will only cease when they have both arrived at the same temperature. Although this is the most perfect vacuum that c be obtained, it is, nevertheless, not a perfect one, as 1 apparently empty space of the tube contains a minute quant of mercurial vapour. It need scarcely be remarked that all other liqni would, like mercury, be supported in a tube by the pressure the air, the height of the column varying with the weight the liquid ; water, for example, being 13^ times lighter th mercury, the height of a column of that liquid would be r; times greater than that of mercury : the column of would therefore measure about 34 feet ; in other words, whl any other liquid than mercury is used, the height of I barometric column will be inversely as the specific gravity ; I specific gravity of mercury at 60 F, is 13-568, the sped gravity of water being taken at !Do not assume that just because we believe a book is in the public domain for users in the United States, that the work is also in the public domain for users in other countries. If, therefore, we bring the hand, or any other part of our body, in contact with a substance having a higher temperature, heat is imparted by that substance to the hand, and we experience the sensation we term heat, If, on the contrary, the hand is warmer than the substance, it imparts some of its heat to the substance, and we then experience the sensation we term cold. = 6'1027( Litre, or cubic decimetre, or 1000 cubic centi- mitres .,......= 6i-0Z7C Decalitre, or cenlislere .....— 610-270] Hectolitre, or decistere .....= 6103-7051 Kilolitre, or Efere, 01 cubic mclre. ■□□□ ; the height of a colui of water corresponding to a column of 30 inches of mercury 60° F. The freezing of water in the joints and crevices of cks acts as a disintegrator and pulveriser even of the hardest f them, thus facilitating the chemical action of the carbon ioxide in the air in converting rocks into fruitful soil. In our comparatively mild winters we : made aware of this great expansive force in the bursting Jwater-pipes and breaking of vessels by the freezing of the rater they contain ; the expansion is nearly ^V ^^^ volume of ^e water, The student must, however, note the distinction ween the expansion on freezing, and the expansion as the i Rater cools from 4° C, to the point it begins to freeze ; it is [his latter expansion that is anomalous, for no other substances Rfeesides water expand on solidifying, 74. 75 Several methods have been devised for determining tb maximum density of water ; the one we describe is that devisei by Hope it consists of a deep glass tube-shaped vessel (b lecture experiments it is frequently made of tin as it renders 1 less costly) having two latert openings, one near the top ai the other near the bottom j thermometer is placed in e of these openings (fig.