92 Mr. M. Carey Lea on the 



by additional evidence. As bases, the alkaloids vary very 

 greatly in strength. A few which contain no oxygen are 

 bases approximating to ammonia in strength. Snch are nicotia 

 and conia. Among those which contain oxygen there is much 

 difference in strength : morphia and codeia are strong bases, 

 and are known to precipitate iron, copper, cobalt, and nickel 

 salts. The weaker alkaloids do not seem to have been examined 

 in this respect, and one therefore was selected for exa- 

 mination, 



Brucia is one of the weaker alkaloids. It is precipitated 

 from its saline solutions by morphia, strychnia, &c. It forms 

 a neutral and an acid sulphate, both crystallizing well The 

 alkaloid itself is very sparingly soluble in cold water ; it is 

 therefore convenient to operate with solutions raised to a tem- 

 perature of 50° or 60° C. The sulphates of zinc, cadmium, 

 copper, manganese, nickel, and cobalt proved to be readily 

 precipitated by brucia. The reaction is always easily obtained 

 and well marked. It is particularly so in the case of cobalt, 

 the rose-red solution of which becomes quickly filled with blue 

 flocks of oxide. 



That weak bases, such as the oxides of zinc, cadmium, and 

 copper, should be precipitated by a weak alkaloid like brucia 

 is not surprising ; but the case is somewhat different with 

 stronger bases like manganous oxide and the oxides of nickel 

 and cobalt. These two last are classed by Mendeleef as " fairly 

 energetic " bases. This, however, can be understood only by 

 comparison ; no base can be considered as a strong one whose 

 neutral salts redden litmus. 



AVhen brucia is added to a solution' of magnesium sulphate, 

 there is no precipitation. Magnesia is a stronger base and 

 its salts are neutral to litmus, not because the acids are more 

 fully saturated by it, but because the potash of the litmus is 

 unable to detach the acids from the base. 



2. Sesquisulphates. 



Chromic sulphate. — The violet salt was obtained free from 

 green salt by acting on the nitrate with sulphuric acid. It 

 was freed from excess of acid by repeated precipitation with 

 alcohol and thorough washing. It had a pale violet colour 

 and satiny lustre. In solution it always gave, when examined 

 with the test liquid, marked indications of the presence of 

 free sulphuric acid. 



Aluminium sulphate. — This was purified from excess of 

 acid in the same manner as the preceding, and gave a similar 

 reaction. 



