6 Dr. E. J. Mills on the First Principles of Chemistry* 



though thus foreseen by Berthollet, was not placed by him on 

 a complete experimental basis ; and the idea that botli he and 

 Bergman perhaps possessed, that each substance has a mass 

 of its own, has probably been investigated but by a single 

 chemist. Later researches have, however, placed the law in a 

 clearer light. Gladstone, for example, in 1855 *, showed that, 

 in a certain group of reactions, " There is nowhere any sudden 



increase If the partition of the bases and acids in the 



mixture really take place at first in atomic proportions, it is 

 evident that, being at full liberty to act and react, the salts 

 arrange themselves according to their respective mass, without 

 reference to their respective atomic weights"!. 



It is, however, more especially to Harcourt & Esson and 

 Guldberg & Waage that we are indebted for the investiga- 

 tion of this subject. Thus, for example, the former chemists 

 examined the deportment of mixtures of potassic permanganate, 

 hydric oxalate, hydric sulphate, and manganous sulphate in 

 presence of a quantity of water which may be regarded as con- 

 stant, the effect particularly traced being the oxidation of the 

 oxalate by the permanganate present. The authors invariably 

 regard the entire weight of a reagent present as active ; and 

 they prove that the amount of oxidation that takes place is 

 directly proportional to the total amount of permanganate re- 

 maining in solution at a given time. In a second inquiry into 

 the reduction of hydric or a similar peroxide by hydric iodide 

 in an aqueous solution of varied content, they show % that 

 " whether the solution contains in each cubic centim. 746 mil- 

 lionths of a gramme of hydric sulphate, or 150 times that quan- 

 tity, 604 millionths of a gramme of potassic iodide or 9 times 

 that quantity, or whether hydric chloride or hydrosodic car- 

 bonate be substituted for hydric sulphate, whether the tempe- 

 rature be 0° or 50° C, and whether the portion of change 

 require for its accomplishment intervals of one or two minutes, 

 or intervals of half an hour or an hour, this reaction still con- 

 forms to the law that the amount of change is at each moment 

 proportional to the total amount of changing substance." The 

 processes above referred to, as well as others confirmatory of 

 them, are represented by Esson as continuous lines ; and where 

 then the case is not too complicated to treat, the law of action 

 is figured graphically as a hyperbola or, ordinarily, a logarith- 

 mic curve. 



* A reduction of all the most important of Gladstone's numerical results 

 has been given by myself in this Journal [IV.], October 1874, where they 

 are shown to agree with the formulae of certain logarithmic curves, the 

 use of which was first introduced into chemistry by Esson. 



t Phil. Trans. 1855, p. 189. % Phil. Trans. 1866, pp. 127, 128. 



