Treatise on general and industrial inorganic chemistry / by Etore Molinari ; third revised and amplified Italian edition translated by Ernest Feilman.
- Ettore Molinari
- Date:
- 1912
Licence: In copyright
Credit: Treatise on general and industrial inorganic chemistry / by Etore Molinari ; third revised and amplified Italian edition translated by Ernest Feilman. Source: Wellcome Collection.
93/734
![and that each componcnt of thè mixture is absorbed in 'proportion io thè mlio in which il is prcsent in thè mixture, or, in other words, in thè proportion in which it would be alh'^orbcd' if thè other components of thè ìnixture were not present, and it were present alone in unaltered’ quantity occupyinq thè ivhole of thè volume, in which case it woiild (hus be present at a reduced pressure. If, for cxainplc, in 100 litrcs of a gascoiis niixturc at a ])rc,ssurc of ono atjìiosphcrc, we bave 20 litrcs of carbon dioxide, tlic pressure due to tlic carbon dioxide (partial pressure) is that is, I of au atinospliere, and thè quantity of carbon dioxide dissolved in tho water jìresent in thè sanie vcssel as thè gas is tlie sanie as woidd be dissolved if tho other gascs did not exist, and tho volunio of 1(X) litros woro occupied exclusively by tho 20 litres of carbon dioxide, in which caso this would be present at a pressure of ‘ of an atinosphero. If in thè 100 litres of thè gascous mixture, 50 litres of carbon dioxide woro present at a total pressure of ono atmosphcrc, tho pressure of thè carbon dioxide would be that is, of an atmospherc, that is, that of thè total gascous pressure. In this case thè quantity of carbon dioxide absorbed is thè sanie as would be absorbed if thè carbon dioxide only were present tlu’oughout thè sanie volume at a pressure of atmosphore. In every case then thè quantity of carbon dioxide absorbed depends upon thè partial pressure exer- cised by this gas in thè mixture and its partial pressure is in tho sanie ratio to tho total pressure as thè volume of thè carbon dioxide is to thè total volume of thè gaseous mixture. Practical illustrations of this law wdll be found in thè chapters on thè industries of liquid carbon dioxide, and catalytic siihihur trioxide, &c. Dalton believed that thè absorption of gases occiirred because their particles entered into thè intermolecular spaces of thè liquid, and tliis was in harniony with thè fact that thè absorption is proportional to thè pressure, biit in this case thè various gases should be absorbed to thè same amomit by thè sanie liquid, which is not thè case ; but thè hypothesis becomes stili more absurd when one remembers that thè absorption becomes less with elevation of thè temperature, wliich increases thè intermolecular spaces. To-day, on thè other hand, it is admitted that a certain attraction takes place between thè molecules of a gas and those of a liquid by means of which thè particles of gas are at first partially drawn into thè liquid, but that these attracted gas particles are in turn detached from thè liquid surface and that equilibriiim and satiiration are established when thè number of gas molecules attracted by thè liquid is equal to thè number which are detached in thè same period of time in virtue of thè kinetic energy wliich they possess, that is, when thè gas in thè liquid and above it is at thè same pressure. The law of Henry is more rigorously explained by means of thè phase rule and of mathematica! expressions of tho equilibrium of various Chemical Systems, as will be explained later. Bunsen determined thè coefficient of absorption of gases by liquids, that is, thè volumes of gas reduced to 0° and to norinal pressure absorbed byunit volume of thè liquid under normal pressure. All thè gases dissolve with more or less evolution of heat and thè solu- bility for a given gas is diminished when a solid substance is dissolved in thè liquid. Certain irregularities shown by certain gases at low temperatures disappear at high temperatures. It has also been observed that on diminishing thè pressure on thè gas above thè liquid, thè total quantity of thè gas corresponding to Henry’s law^ is not immediately liberated, but that a kind of supersaturation continues for some time, and is only removed by agitating thè liquid or by introducing a porous body which carries down air in its pores. The question whether thè gas absorbed by a liquid is present as sudi or in thè liquid state has not been settled, and although thè gas and thè licpiid form a homogeneous mixture, thè particles of gas appear to retain their gaseous character, provided that one does not descend below thè criticai temperature of any individuai gas, in which case one vould have to adiiiit that thè gas must be liquefied. SOLUBILITY OF GASES IN SALT SOLUTIONS. This pheuomenon has been studied from a biological standpoint in order to see in what manner carbon dioxide and oxygen are absorbed by thè blood, which may be considered](https://iiif.wellcomecollection.org/image/b28134187_0095.jp2/full/800%2C/0/default.jpg)
