RECENT PROGRESS IN CHEMISTRY. 529 



H. B. Baker communicated to the London Chemical Society results of 

 his experiments on the influence of moisture in the combustion of car- 

 bon and of phosphorus in oxygen, his conclusions being that the com- 

 bustion of dry charcoal in dry oxygen is incomplete and slower than 

 in ordinary moist oxygen. In the discussion which followed Mr. Ba- 

 ker's paper, Dr. Armstrong pointed out the importance of these new 

 facts in defining more accurately conceptions of chemical action, and 

 suggested that chemical action is " reversed electrolysis." In his ad- 

 dress as President of the Chemical Section of the British Association 

 for the Advancement of Science (September 10, 1885), Dr. Armstrong 

 further discussed this subject, and stated that the idea conveyed by 

 the expression " reversed electrolysis " is found in the writings of Fara- 

 day, neglect of whose teachings retards the progress of chemistry. 



Liquefied ammonia at 65 does not combine with sulphuric acid, 

 but swims on its surface without mixing with it. Donny and Mareska 

 long ago showed that sodium retains its luster in liquid chlorine at 

 80, and quite recently Professor Dewar demonstrated that liquid 

 oxygen is without action on sodium, potassium, phosphorus, solid sul- 

 phuretted hydrogen, and solid hydriodic acid. He further experi- 

 mented with other substances normally active, and found their affinity 

 at very low temperatures destroyed. 



The speed of chemical reactions is an important factor in chemical 

 theory, the study of which has but recently begun. Wenzel long ago 

 held that the affinity of metals for a common solvent, such as nitric 

 acid, was inversely as the time necessary to dissolve them, and he ex- 

 perimented with small cylinders partly protected by wax. Gladstone 

 and Tribe have made attempts to ascertain the rate at which a metallic 

 plate precipitates another metal from a solution, and they announced 

 a definite law. Professor John W. Langley has since shown that, 

 while their experimental work was correct, their method was faulty, 

 and the results fallacious ; he thinks it probable that the true law of 

 chemical action where one metal precipitates another should be thus 

 stated : The time during which one atom replaces another in a com- 

 pound molecule is constant, and the total rate of chemical action varies 

 directly as the mass of the reacting body in solution. 



In his address before the Chemical Section of the American Asso- 

 ciation for the Advancement of Science, at Philadelphia, Professor 

 Langley discussed the problems of chemical dynamics, and pointed 

 out the rich store of promise in this neglected field. Physics deals with 

 three quantities space, mass, and time. Chemistry has too long been 

 content with studying the changes of matter in terms of space and mass 

 only that is to say, in units of atomic weight and atomic volume. 

 The discovery of a time-rate for the attractions due to affinity is des- 

 tined to throw new light on chemical science, and to render it capable 

 of mathematical treatment. 



A prodigious amount of work has been done in thermo-chemistry, 

 vol. xxix. 34 



