Januaey 14, 1910] 



SCIENCE 



49 



ents of the new substance formed tends 

 to retain its original characteristics as 

 far as the new conditions to which it 

 has ieen subjected permit. In reality 

 every chemist is well aware of this, though 

 as far as I know the idea has never before 

 been stated in so many words. The degree 

 to which an element loses its original prop- 

 erties on entering into combination with 

 other elements depends very largely upon 

 whether the chemical change involved is 

 a drastic or a mild one, which in turn is 

 principally determined by the energy ac- 

 companiments of the reaction. In the 

 study of solutions, which in general repre- 

 sent rather compounds formed by rela- 

 tively mild changes as compared with 

 many of the stereotyped chemical reac- 

 tions, the thought just expressed is particu- 

 larly helpful. So, for instance, sodium 

 has a great affinity for the elements of 

 water, upon which the solubility of sodium 

 compounds in water largely depends. On 

 the other hand, sodium is inert toward 

 hydrocarbons, which fact is at the basis of 

 the insolubility of sodium salts in hydro- 

 carbons. An element with pronounced 

 chemical characteristics like sodium, for 

 example, will retain to a high degree its 

 chemical predilections even after it has 

 entered into combination with other ele- 

 ments. Thus if we take sodium oleate, in 

 which the metal is combined with the 

 large fatty oleic radical, we nevertheless 

 find that this soap dissolves in water. 

 Here again the great affinity of sodium for 

 water manifests itself, and though the 

 metal is chained to the fatty radical which 

 of itself exhibits no inclination to unite 

 with water, yet this radical is dragged 

 along into solution as it were by the great 

 chemical attraction which sodium still has 

 for water. But the combination which 

 water and sodium oleate form is after all 

 but a loose one, as one would naturally 



expect from what has been stated. The 

 fact that a solution of sodium oleate boils 

 but slightly higher than pure water shows 

 that there is but little affinity between 

 water and the soap. Again, the insolubil- 

 ity of sodium oleate in hydrocarbons shows 

 that the oleic radical, though it is known to 

 have affinity for hydrocarbons and fats, is 

 yet unable to drag the sodium with it into 

 solution. On the other hand, however, the 

 affinity of the oleic radical for fatty sub- 

 stances does manifest itself when a strong 

 aqueous soap solution is brought into eon- 

 tact with greasy matter on clothes, etc., for 

 by virtue of this affinity the grease is 

 loosened from the fabrics, and though not 

 dissolved, it is nevertheless emulsified so 

 that it can be removed mechanically with 

 the soap solution. Numerous other ex- 

 amples illustrating the principles stated 

 might here be mentioned. I am at present 

 engaged in the work of collecting these. 

 Before the advent of the physical theories 

 of solutions considerable work was done in 

 ascertaining the chemical relation.ships 

 that must exist between solvent and solute 

 in order that solution may take place; 

 but during the last two decades this work 

 has been practically discontinued, which is 

 particularly unfortunate. It clearly indi- 

 cates, however, how our so-called modern 

 conceptions of solutions, which have been 

 pressed upon the scientific public by a 

 species of propagandism that is, and it is 

 to be hoped will remain, quite unrivaled 

 in the history of chemi.stry, have really 

 stood in the way of progress. 



In some quarters the idea is still preva- 

 lent that electrolytes are essentially dif- 

 ferent from non-electrolytes in their chem- 

 ical behavior. This is thoroughly fallaci- 

 ous, for all chemical changes that occur in 

 electrolytes can mow be reproduced as to 

 type and as to rapidity in the best of insu- 

 lators. An electrolytic solution behaves 



