160 THE NEW WORLD OF SCIENCE 



carbon monoxide would be of great commercial and industrial 

 importance. Because of the peculiar physical and chemical 

 properties of the gas, its removal from the air is very difficult. 



Two mixtures were finally discovered which were satisfactory 

 absorbents. The first of these consisted of fuming sulfuric 

 acid and iodine pentoxide, with pumice as the carrier (Hoola- 

 mite). This mixture is active for 2 hours at room temperature 

 (the gas-air mixture being passed at the rate of 500 cc. per 

 minute per sq. cm. of cross section) and almost as long at o. 

 About 75-8o per cent, of the iodine pentoxide is utilized during 

 this time. The sulfur trioxide which is given off is removed 

 by the use of a layer of active charcoal beyond the carbon 

 monoxide absorbent. But the sulfur dioxide, which is slowly 

 formed as the result of this absorption, gives serious trouble on 

 long continued use of the canister. Another disadvantage 

 arose from the fact that heat was evolved in the reaction of 

 carbon monoxide and the absorbent. This could be overcome 

 by the use of a cooling attachment (a metal box filled with 

 sodium thiosulfate-pentahydrate) though it nearly doubled the 

 size of the canister. Still another disadvantage of this ab- 

 sorbent was the fact that it absorbed enough moisture from the 

 air of average humidity in several hours to destroy its activity. 



Incidentally a simple and inexpensive method for the pro- 

 duction of iodine pentoxide was perfected. It was also shown 

 that the green color resulting from the action of carbon 

 monoxide on Hoolamite could be used as a very sensitive detec- 

 tor for the presence of carbon monoxide in air. 



The second and far superior absorbent consists of a mixture 

 of metallic oxides. This originated from the observation that a 

 specially precipitated copper oxide activated with I per cent, 

 silver oxide was an efficient catalyzer for the oxidation of 

 arsine by the oxygen of the air. This led to the study of other 

 oxides and mixtures and finally it was found that a three- 

 component mixture of cobaltic oxide, manganese dioxide and 

 silver oxide, in the proportion of 20: 34: 46, prepared by the 

 interaction of silver permanganate with moist hydrated cobaltic 



