ANIMAL BASES. 



Urea is not precipitated from its solutions by any metallic salt 

 nor by tannin. 



Urea was subjected to an ultimate analysis by Berard and by 

 Prevost and Dumas, but the proportion of hydrogen obtained by 

 these chemists was greatly in excess. It was analyzed by Dr 

 Prout in 1818,* with great precision. He obtained 

 Carbon, . 19-99 

 Hydrogen, . 6-66 

 Azote, . 46-66 



Oxygen, . 26-66 



100- 



In Dobereiner's supplement it is stated that Wohler and Lie- 

 big made two analyses of urea with the following results : 

 Carbon, 20-02 20-20 



Hydrogen, . 6-71 6-60 



Azote, . 46-73 46-76 



Oxygen, . 26-54 26-44 



100-00 100-00 



I do not know where these analyses were published. But it is 

 obvious at a glance that they coincide most satisfactorily with 

 the results previously obtained by Dr Prout. 



Some idea of the atomic weight of urea may be formed from 

 the constitution of nitrate of urea and oxalate of urea. The 

 former gives 7*45, and the latter 7-52, the mean of which is 

 7-485. Now, if its atomic weight be 7*5, its constitution must 

 be 



2 atoms carbon, . = 1-5 or per cent. 20*00 



4 atoms hydrogen, . = 0'5 ... 6-66 



2 atoms azote, . =3-5 ... 46-66 



2 atoms oxygen, . =2-0 ... 26-66 



7-5 100- 



which corresponds exactly with the analysis of Dr Prout. 



Wohler discovered that when a solution of sal-ammoniac is 

 poured upon cyanate of silver recently precipitated, chloride of 

 silver is formed, and instead of cyanate of ammonia, which ought 

 to be formed, if we evaporate the solution we get white crystals, 



* Annals of Philosophy, first series, xi. 353. 



