554 
of the reactiiig substaiices. One oan öiibstitute a niti'O (NO,) group in 
a compound by the groiap (NHj on warming it witli a mixture of 
ammonium hydroxide and a ammonium salt and on the other hand, 
NH, is replaced by NO, when the salt is warmed with a nitrite solution. 
(NH,); 
■ (Nh;)/ 
Ci 
Cl, + H,0 
Co 
(H,0) 
Cl, 
This hydrolysis reaction is catalytically accelerated by the presence 
of OH' ions and the velocity is proportional to the concentration of 
hydroxide ions. 
^ (NO,) J (NO,), J 
are strong bases and ean be prepared in solution. The base obtained 
from the purpureo cobalt chloride is the aquopentammine hydroxide 
(NH.), 
Co 
H.0 
(OH), 
Chemical Laboratory, Muir Central College, Allahabad, India. 
