1880.] NEW YORK ACADEMY OF SCIENCES. 187 



violently uttacks plutinuni at low teini)eratures, it is witliout 

 action upon tlie metal between 300° and 1,300°, and begins to act 

 ii])on the platinum above the latter temperature, the action be- 

 coming violent at 1,600° to 1,700° C. 



Liquefied ammonia at — G5° 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 hister in 

 liquid chloririe at —8')°, and quite recently Prof, Dewar demon- 

 strated that liquid oxygen is without action on sodium, potassium, 

 phosphorus, solid su]j[)huretted hydrogen, and solid hydriodic 

 acid. He further experimented with other substances normally 

 active, and found their affinity at very low temperatures de- 

 stroyed. =" 



(10.) Attempts have been made to solve the problem of ci gen- 

 eral theory of chemical action by means of the data of electroly- 

 sis and of thermo-chemistry. The subject is further complicated 

 by the phenomena of induction, of i)redisposing affinity, and of 

 influence of mass. Lastly, but not least, the term affinity is 

 itself used in a vague way, expressing different ideas at different 

 times and by different authors, some writers doubting the expe- 

 diency of employing the word at all. and favoring the more 

 general expression chemical action. The true nature of chemi- 

 cal action has yet to be satisfactorily explained ; only the most 

 general conclusions are fairly deduciblo from the data in hand, 

 namely : " that each chemical substance which forms a member 

 of any changing system exerts a specific action on the course of 

 the changes which that system undergoes." ^' 



Chemists are beginning to realize that many phenomena re- 

 garded as simple in character are in reality quite complex. A 

 single example must suffice. From Lavoisier's day until a few 

 years ago the combustion of carbon monoxide in the air, or in 

 oxygen was regarded as a very simple phenomenon, satisfactorily 

 explained by the equation : 



200 -f 0, = 2C0, 

 in which two molecules of the gas unite directly with one of 

 oxygen, producing two molecules of carbon dioxide. In 1880, 

 however, Mr. H. B. Dixon ^- demonstrated that this reaction 

 takes place only in the presence of aqueous vapor; this necessi- 

 tates an entirely different explanation, as indicated in the follow- 

 ing equations : 



(1.) CO -f- H„0 = CO, -t- H, 

 (2.) 2H, 4- 0, = 2H,0, 

 that is to say, the carbon monoxide decomposes the water, form- 

 ing carbon dioxide and setting hydrogen free, Avhicli latter gas 

 unites with the free oxygen and thus reconstructs the water. 



Within a twelvemonth, however, Traube " has shown that 



