190 RESEARCHES UPON THE CHEMICAL PROPERTIES OF OASES. 



Ferricyanide of potassium Unchanged. 



Calcium liypobromite containing excess of lime water. . Unchanged. 



Fuming nitric acid Oxidation to carbon dioxide. 



2. Reactions at High Temperatures. 



Iodic acid in crystals is reduced by carbon monoxide, yielding carbon dioxide 

 and iodine vapors at 90° (De La Harpe, Fres. Zeitschr., 1889, p. 391). De La Harpe 

 recommends this method for the recognition of carbon monoxide in air. As higher 

 olefines reduce iodic acid at about the same temperature as carbon monoxide, it 

 would be necessary to remove them. According to my experiments, it would be 

 necessary also to remove acetylenes, benzol and alcohol vapors, inasmuch as these 

 substances exert an action similar to that of olefines. The lower paraffins are with- 

 out action up to temperatures at which iodic acid dissociates. 



Potassium iodate in crystals is not reduced by carbon monoxide at the melting 

 point of barium nitrate (593°). Carbon monoxide undergoes a decomposition in 

 presence of certain metals at high temperatures, according to the reaction : 



2 CO = CO2 + C. 



Il^'ickel causes such a change to occur at 350°, a very small quantity of the metal 

 serving to decompose a large volume of the gas (Mond. and Quincke, Cliem. News, 

 1891, p. 108). Iron is said to cause a similar decomposition at 227° (Bell, Chemical 

 Phenomena, of Iron Smelting, pp. 80, 81). I have made the following experiment 

 with palladium : 



Palladium asbestos was heated in a porcelain tube in a slow stream of pure 

 carbon monoxide, air having been expelled from the apparatus previous to the heat- 

 ing by means of the carbon monoxide stream. At a moderately high temperature 

 (it was below redness) carbon dioxide was produced in such quantity as to cause a 

 strong reaction in lime water. 



Carbon monoxide reduces oxide of iron at 240°, according to BeH. 



Howe {JEng. and Min. J., L, p. 426) states that incipient reduction of iron 

 oxide by carbon monoxide occurs at 141°. 



The temperature of reduction of oxide of iron by carbon monoxide is unques- 

 tionabl}^ much lower than in the case of methane and ethane. 



Carbonic oxide is absorbed by soda lime at a temperature of 200°-220°, yielding 

 sodium formate. Moisture promotes the reaction (Merz and Weith, Ber., 1880, 

 p. 718). The reaction is as follows: 



NaOH + CO = HCOONa. 



