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IX. 77jf Conditions of the Evolution of Gases from Homogeneous Liquids. 

 By V. H. VELKY, M.A., University College, Oxford. 



Communicated by A. VERNON HARCOURT, M.A., F.ff.S., Lee's Reader in Chemistry, 



Christ Church, Oxford. 



Received May 5, Read May 31, 1888. 



I. Introduction. 



THE evolution of a gas, as a product of a chemical change, from a homogeneous liquid is 

 among the earliest and most common experiences presented to a student of chemistry. 

 Thus, oxygen and nitrogen, among the elementary gases, and nitrous oxide, nitric oxide, 

 carbonic oxide, and hydrogen sulphide, among the compound gases, can be readily 

 prepared either from certain salts in a state of fusion, or from aqueous or acid 

 solutions of certain compounds. The effects produced on the rate and magnitude of 

 these changes by varying the conditions of mass, temperature, pressure, and material 

 of the containing vessel have not, hitherto, attracted the attention of investigators. 

 In preference, similar dynamical problems have been studied of chemical changes 

 occurring either between two or more gases, forming a gaseous product, or between 

 homogeneous liquids, or between solutions of solids. 



In all these instances the reagents and their products are in the same physical 

 condition, gaseous or liquid, as the case may be. Of such a character are the 

 investigations of BUNSEN, v. MEYER, HORSTMANN, and the more elaborate researches 

 of DIXON on the conditions of chemical change occurring between hydrogen and 

 certain combustible gases. While among changes between homogeneous liquids or 

 solutions of solids, should be mentioned the experiments of BERTHELOT and PEAN 

 DE SAINT GILLES, and of MENSCHUTKIN, on the formation of ethereal salts from 

 organic acids and alcohols, of HARCOURT and ESSON on the reactions between oxalic 

 and permanganic acids, and between hydrogen iodide and hydrogen peroxide, and 

 of GLADSTONE on the reaction between ferric salts and sulphocyanides. 



Experience thus far has shown that a chemical change from which a gas results is 

 often complicated in itself, or is accompanied and modified by other changes yielding 

 products not susceptible of convenient estimation. Sometimes, also, some portion of 

 the compound whose rate of decomposition is being measured is vaporised unchanged. 

 In the present paper I have the honour of laying before the Royal Society an account 



MDCCCLXXXVITI. A. 2 L 23.8.88 



