Elements of chemistry : including the most recent discoveries and applications of the science to medicine and pharmacy, and to the arts / by Robert Kane.

  • Kane, Robert, 1809-1890.
Date:
1842
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Licence: Public Domain Mark

Credit: Elements of chemistry : including the most recent discoveries and applications of the science to medicine and pharmacy, and to the arts / by Robert Kane. Source: Wellcome Collection.

Provider: This material has been provided by the National Library of Medicine (U.S.), through the Medical Heritage Library. The original may be consulted at the National Library of Medicine (U.S.)

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    then first obtained by himself and his illustrious associate Black, he converted it, though still without changing its fundamental prin- ciple, from the machine of Newcomen, which had been rejected from practice for its inefficiency and expense, into the instrument which, after the art of printing, must be considered as the most powerful material agent of human improvement and civilization of which mankind has ever obtained possession. The similarity of constitution of gases and vapours has been already pointed out on many occasions, and particularly*™ page 21, the conversion of gases into liquids by the application of great pressure has been detailed. A liquefied gas so con- tained in a close vessel is precisely in the condition of water heated in a digester, as in the apparatus figured in page 80, far above its boiling point, and generating steam possessed of considerable tension. On this analogy has been founded an in- teresting speculation concerning the temperatures at which the gases would, at or- dinary pressures, assume their liquid form, that is, their boiling points when liquid, thus : At 44 5° the tension of liquid nitrous oxide is 50 atmospheres. At 320° 44 For 125° an increase of tension of ... 6 atmospheres. Steam exerts a pressure of 50 atmospheres at . . . 511-5° and of 44 ... 4975° For six atmospheres the difference is 14 0°, or just the same. Liquid carbonic acid exerts a pressure of 25 atmos. at 32° ) -nifiprpnpp 2n° and of 20 12° $ uinerence> M The tension of steam is 25 atmospheres at .... 4395° ) T1ifrPrpri„,i 9,0 20 . . - . 4185° ] ^merence> < Muriatic acid exerts, when liquid, a tension of 25 atmos. at 25° ) j)jfference 32° and of 20 3° > Steam balances 25 atmospheres at 439 5° ) ■n;ffllr»n_0 91o 20 ........ 4185o ^uierence, ^1 Ammonia liquefies and exerts a pressure of 6-5 atmos. at 50° ) -ni«bron/.o ia° and of 5 32° S umerence> 1B Steam exerts a pressure of 65 atmospheres at . . . 326° I T)iffPrPn(.p 10-50 It is hence evident that, in every case, the rate of increase of elasticity of these gases with the temperature follows the same law as that of steam ; and there is, therefore, good reason to believe that, if the elasticity were diminished to one at- mosphere, the reduction of temperature necessary to effect it should be regulated by the same law as that of watery vapour; the gases should then, under the ordi- nary pressure of 30 inches, become liquid, and when liquid, their boiling points should be: Nitrous oxide = _ 2524° Fahrenheit. Carbonic acid = — 230-8° Muriatic acid — — 2020° Ammonia = — 634° The great increase of elasticity which these liquefied gases acquire by a change of temperature, limited to a very few degrees, has led to sanguine opinions of their advantages as a source of power in machines. No experiments at all sufficiently satisfactory to be decisive upon the question have as yet been made. There are some other properties of gases which, although closely connected with the subject now discussed, I shall postpone, in order to introduce them where they are found to be of the most practical importance. Thus, the manner in which gases spread through each other, in virtue of their diffusive power, will be descri- bed under the head of Atmospheric Air, to the proper constitution of which this law is indispensable. The relation of gases to water, their solubility in that and other liquids, and the various modes of depriving them of moisture for the purpose of chemical experiments, shall enter into the history of the physical and chemical properties of water.