Introduction to the study of inorganic chemistry / by William Allen Miller.

  • Miller, William Allen, 1817-1870.
Date:
1871
Catalogue details

Licence: Public Domain Mark

Credit: Introduction to the study of inorganic chemistry / by William Allen Miller. Source: Wellcome Collection.

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    Freezing and Boiling of Water. 45 . an elasticity sufficient to balance the pressure of a column of r mercury of 760 millimetres, i cubic inch of water producing r nearly a cubic foot of steam. Pure water has neither taste nor smell, and it is generally i supposed to be colourless, though when seen through a depth of 5 or 6 metres it has a delicate and faint tinge of blue. UVhen cooled sufficiently, it becomes converted into the t transparent solid form of ice. The point at which pure ice rmelts, or the freezing point, as it is usually called, always coccurs at e.xactly the same temperature, if the ice is no. r.-e.\pcscd to ])ressure. Hence the melting point of ice has ■been made die starting point or 0°, the zero, as it is termed, lof the centigrade thennometric scale.* Again, if the tem- ;perature of water be raised sufficiently high’ the liquid assumes the form of gas, while bubbles of steam rise throuo^h the heated liquid and break upon its surflice, passing off as invisible vapour. The water is said to boil, and its vapour 'S then of an elastic force just sufficient to balance the pre.s- >ureoftheair upon its surflice, whatever that pressure may oe. The temperature at which pure water boils under eciual uiessures is found to be quite as uniform as its freezing oomt. Ihis boding point of water serves, therefore, as a eecond fixed point upon the thennometric scale, and it has oeen agreed to call the point at which the mercury stands nn boiling water 100° on the centigrade scale; the observa- tion being always made when the pressure of the air upon I he surface of the boiling water, as indicated by the baro- Meter, is equal to that of a mercurial column 760 mm lono- ■hen measured at 0° C. One degree of the centigrade scale ppresents the looth part of the apparent expansion of the mercury m the thermometer between the freezing and the Oiling points of water.f ' L^cvI^ruJ-n’ ’’r''' in ih 'l,c freezing point is lowerc.l .+ If '‘‘-■P‘-''i'hng on the qu.intity and kind of salt vera nay l^e rai.^ed kind