54 CYANAMiD — manu:^acture:^ che:mistry and use:s 



Glass-sand plus 



Cyanamide 



nitrogen 



milligrams Kaolin 



Initial 33.00 



After 15 hours. •• — 



'* 2 days 31.16 



•' 3 " ••-. 30.57 



" 6 " .... 30.28 



I per cent, 

 manganese 

 hj'droxide 



33.00 



5.06 



0.00 



I per cent. 



iron ore 



No. I 



33-00 



25-25 



14.78 



8.62 



4.00 



I per cent. 



iron ore 



No. 2 



33- 00 



30.80 

 26.48 

 22.79 

 17.24 



0,1 per cent, 

 manganese 

 hydroxide 



33-00 



30.18 

 28.33 

 25.25 



It has been shown in the preceding experiment that glass 

 sand has practically no activity. Hence, o.i grams of man- 

 ganese hydroxide is more effective than 100 grams of kaolin. 

 The surface exposed by the kaolin is clearly much greater than 

 that exposed by the smaller quantities of iron and manganese 

 hydroxides, and the catalytic activity of the latter is therefore 

 essentially connected with their chemical properties. 



Another experiment was made to compare the activity of 

 iron hydroxide, aluminium hydroxide and silicic acid. The 

 iron and aluminium hydroxides were prepared by precipita- 

 tion; a sample of each was mixed in the undried condition with 

 4 times its weight of glass sand, the mixture then containing 

 2.6 per cent, iron oxide in the one case and 1.6 per cent, 

 alumina in the other. The aluminium hydroxide and the pre- 

 cipitated silicic acid were dried and applied separately to twice 

 their weight of glass sand. One hundred grams of each of 

 the above mixtures was treated with 20 cc. of cyanamide solu- 

 tion containing 33 mg. of cyanamide nitrogen. The sub- 

 sequent analyses are as follows : 



Silicic acid has a slight ability to convert cyanamide; and 

 aluminium hydroxide has somewhat more. 



