8 12 THE POPULAR SCIENCE MONTHLY. 



interest awakened of late in electricity, have given rise to numer- 

 ous researches aiming at a representation of chemical reactions 

 as mere transformations of heat-energy or electricity. And, 

 finally, most skillful investigations are being made, and most sug- 

 gestive hypotheses advanced as regards the possible distribution 

 of atoms within the molecules, under the supposition of their 

 remaining in a state of equilibrium ; and thus the way is pre- 

 pared for a higher conception of the atoms not motionless and 

 mutually equilibrated, but involved, like the planets of our solar 

 system, in complicated movements within the molecules. Works 

 of importance have appeared of late in each of these directions. 

 But no other domain has lately been explored with such a feverish 

 activity as the vast domain of solutions ; and to these researches 

 we must now turn our attention. 



In former times it was supposed that if some table-salt or 

 sugar (or any other solid, liquid, or gas) is dissolved in water or 

 in any other liquid, the particles of the dissolved body will simply 

 spread, or glide, between the particles of the solvent, and simply 

 be mixed together just as if we had made a mixture of two 

 different powders or two gases. But on a closer study a succes- 

 sion of most complicated and unexpected phenomena was revealed, 

 even in so simple a fact as the solution of a pinch of salt in a 

 tumbler of water. The solutions proved to be the arena upon 

 which phenomena cease to be purely physical, and become chem- 

 ical, and they were studied accordingly with the hope that they 

 might give a physical cue to chemical reactions. Hundreds of 

 researches are contributed every year to this subject ; * and al- 

 though there is yet no final result to record, we are bound never- 

 theless to examine the present state of investigations which so 

 much interest and excite chemists, f 



* The committee appointed by the British Association for reporting on the bibliography 

 of solutions had catalogued no less than 255 papers, which appeared in 1890, in a few 

 periodicals only. The total was at that time 930 papers. 



\ We know no general review of this extremely complicated question which we might 

 recommend to the general reader. The address delivered by Prof. Orme Masson before the 

 Australasian Association for the Advancement of Science, in January, 1891; Prof. S. U. 

 Pickering's Report to the British Association, in 1890, on the hydrate theory of solution, 

 followed by a most interesting discussion between Profs. Gladstone, Arrhenius, Armstrong, 

 Fitzgerald, Van 't Hoff, Lodge, Ostwald, and Ramsay, and the elaborate report, by W. N. 

 Shaw, on electrolysis (British Association Reports, 1890, Leeds), are excellent sources of 

 general information. Ostwald's work, Solutions (English translation in 1891), as well as his 

 Lehrbuch der allgemeinen Chemie (Leipsic, 1885 ; new edition of first volume in 1892), and 

 the review, Zeitschrift flir physikalische Chemie, which he publishes since 188V, unhappily 

 take but little notice of the chemical aspects of the question. Mendeleeff's foot-notes in 

 his most remarkable Principles of Chemistry (London, 1891) are perhaps, on the whole, the 

 best means for gaining a general and impartial insight into the whole question. Though 

 himself one of the earliest promoters of the hydrate or chemical theory of solutions, he 



