ACTION OF SOME OF THE ALKALINE SALTS. 227 



acid. This is different from what takes place with the citrate, 

 which when boiled upon the lead-salt dissolves it, and no length 

 of ebullition will produce a precipitate. The action of the 

 tartrate is first to dissolve the sulphate, decompose it in part, 

 and form a double tartrate of lead and ammonia, which last 

 salt is subsequently decomposed by continued contact with 

 water, or still more rapidly by its solution being boiled. 



Acetate of ammonia. — This salt also'dissolves to some extent 

 the sulphate of lead, but not so readily as either of the above 

 salts. If the solution be boiled and evaporated to dryness, 

 crystals of sulphate of ammonia are obtained, and an uncrys- 

 tallizable salt of lead, probably an acetate of lead and ammonia; 

 from the difficulty of separating the sulphate of ammonia from 

 it, it is impossible to pronounce positively whether it is a double 

 salt or simply an acetate of lead. We see in this reaction the 

 existence of a soluble salt of lead and the sulphate of ammonia 

 simultaneously in the same solution, without a precipitate being 

 formed. 



Oxalate of ammonia dissolves but slightly the sulphate of 

 lead, owing no doubt to the impossibility of forming a double 

 salt; but it will nevertheless decompose largely, the sulphate 

 furnishing the oxalate of lead. 



Muriate of ammonia, if boiled with the sulphate of lead, will 

 decompose it instantly, furnishing the chloride of lead and sul- 

 phate of ammonia. 



The nitrate of ammonia does the same, forming nitrate of lead 

 and sulphate of ammonia. 



The carbonate and succinate of ammonia produce similar 

 effects. 



The action of most of the corresponding salts of potash and 

 soda was examined, and with very similar results. The fact is 

 it would appear that those alkaline salts which dissolve the 

 sulphate of lead decompose it without reference to the time 

 occupied in the solution, as in the case of the carbonate of am- 

 monia, which decomposes the sulphate at the very instant of its 

 solution; and it is impossible to detect at any one time other 

 than a trace of lead in solution, whereas the quantity of sul- 

 phuric acid is constantly increasing. 



The explanation is clear: the sulphate of lead is a salt with 

 a strong acid and feeble base; the alkaline salts used contain 



