IO2 r i^;' Bi'olOgkal Chemistry. 



(In this case a mixture of acetamide and ammonium acetate 

 is obtained.) 



CH 3 -CO 



The substance obtained in these reactions is known as 

 acetamide, and may be regarded as a derivative of 

 ammonia, NH 3 , in which one hydrogen is replaced by the 

 acetyl group, CH 3 CO (see p. 100). Acetamide can also be 

 obtained by the distillation of ammonium acetate 



CH 3 .COONH 4 = CH 3 .CO NH 2 



The acid amides, of which acetamide is the type, are 

 decomposed on heating with mineral acids and alkalis, 

 with evolution of ammonia (which, when an acid has been 

 employed for hydrolysis, combines with it to form an 

 ammonium salt) yielding the acid from which they are 

 derived 



Acetamide, CH 3 CO NH 2 , forms colourless crystals, 

 melting point 82, boiling point 222, with a character- 

 istic mouse-like odour. It is readily soluble in water and 

 alcohol. The amides of the higher acids are not so readily 

 soluble in water. 



ADDENDUM TO PART VIII. UREA. 



Closely allied to the acid amides is a substance of 

 great importance in physiology, namely, urea or carbamide. 

 In this form mammals excrete the greater part of their 

 waste nitrogen in the urine. It is also a substance of 

 considerable interest in the history of chemistry, for its 

 synthesis by Wohler in 1828 forms the first example of 

 the artificial preparation of an animal product. 



Wohler found that when an aqueous solution of 

 ammonium cyanate, NH 4 CNO, was evaporated, the 

 atoms in the molecule underwent a rearrangement, and 



