January 13, 190^.] 



SCIENCE. 



53 



to petrography is much the same to-day as 

 it was in regard to alloys a few years ago 

 and we may reasonably expect as satisfac- 

 tory results from rocks as from metals. 

 More and more people are experimenting 

 with fused salts and the new geophysical 

 laboratory at Washington is planning to 

 study igneous rocks in the same thorough 

 way that van't Hoff studied the Stassfurt 

 deposits. The problem is a difficult one 

 experimentally, but it can and will be 

 solved. 



The classification of electrochemistry 

 under the phase rule is a problem of the 

 immediate future. Some work has been 

 done already, but it is confined to the dis- 

 cussion of the electromotive forces of cer- 

 tain reversible cells. What I mean is some- 

 thing vastly wider than this, the applica- 

 tion of the phase rule to all electrolytic and 

 electrothermal processes. Since electro- 

 chemistry is essentially chemistry, a classi- 

 fication which is of fundamental impor- 

 tance in chemistry must be equally neces- 

 sary in electrochemistry. 



The extension of the phase rule to or- 

 ganic chemistry is an achievement about 

 which we like to dream, but the realization 

 of it seems far off. To treat a large por- 

 tion of organic chemistry as a system made 

 up of carbon, hydrogen and oxygen will 

 some day be possible ; but at present we are 

 balked by so-called 'passive resistances to 

 change.' Theoretically methyl ether, 

 (CHJ.O, and ethyl alcohol, C^H-OH, are 

 two modifications of the substance CgHgO 

 and they shovild be mutually convertible. 

 Practically they are not. Only one of the 

 three dibrombenzenes can theoretically be 

 the stable form. Actually, we can not con- 

 vert any one of them directly into either 

 of the other two. 



In spite of all this there is really quite a 

 mass of material waiting to be worked up. 

 Reversible equilibrium between hydrogen 

 and oxygen can be realized at all tempera- 



tures. Reversible equilibrium between car- 

 bon, carbon monoxide and carbon dioxide 

 is possible above 200°, while reversible 

 equilibrium between carbon, methane, 

 acetylene, ethane and hydrogen can be ob- 

 served above 1200° without catalytic 

 agents. Carbon monoxide and w^ater re- 

 act at 430° in presence of copper. Methane 

 can be made from carbon monoxide and 

 hydrogen at 250° in presence of nickel, 

 w'hile methyl alcohol can be changed to 

 carbon monoxide and hydrogen by zinc 

 dust. The decomposition of alcohols into 

 aldehydes, or ketones, and hydrogen is re- 

 versible. Aldehydes can be changed into 

 carbon monoxide and paraffines, though the 

 reverse reaction has not been accomplished 

 satisfactorily. Methylal and acetal are 

 formed by a reversible reaction, while the 

 ester formation has been studied for years. 

 Formic acid decomposes into carbon mon- 

 oxide and water when heated by itself, and 

 into carbon dioxide and hydrogen when 

 heated in presence of rhodium. Starting 

 from carbon monoxide and caustic soda we 

 can make sodium formate, carbonate and 

 oxalate. 



As yet only a few of these reactions have 

 been studied with care and we do not know 

 how many of them are reversible or what 

 are the temperature limits. We do not 

 even know whether colloidal metals act 

 more effectively than the pulverulent 

 metals, although it is very probable that 

 they do. While we can not yet tell how 

 far we may be able to go, it is clear that 

 the attempt to apply the phase rule to 

 organic chemistry opens up a most inter- 

 esting field of research both as regards or- 

 ganic chemistry and as regards the theory 

 of catalytic agents. 



The usefulness of the phase rule in study- 

 ing basic and double salts is being realized 

 more and more by our friends the inor- 

 ganic chemists. The recent work on the 

 changing solubility of the hydroxides of 



