266 Chemistry. [Lecture S3. 



the volatile alkali not possessing the power of 

 taking away the whole of the acid from the mer- 

 cury. The fixed alkali requires some time to 

 precipitate the mercury. 



Copper, or the calx of copper, is another cri- 

 terion of the presence of the volatile alkali, 

 which produces with it a blue solution ; but this 

 does not answer if the quantity of alkali is ex- 

 ceedingly small. Verdigris added alone does 

 not tinge water, but falls to the bottom in a 

 subtile powder ; yet if the water contains any 

 quantity of volatile alkali, it dissolves the ver- 

 digris, and tinges the water a beautiful blue 

 colour. 



There are some solutions of lime which con- 

 tain the muriatic acid, as the liquid shell which 

 is made by adding to oyster-shells one-half their 

 weight of muriate of ammonia, and then ex- 

 posing them in a crucible to a strong heat. 

 This forms the fixed ammonia, the muriatic acid 

 joining with the lime, but uniting with more 

 than it can retain in solution : therefore, when 

 dissolved, it parts with some quick-lime, which 

 gives the water the properties of lime-water ; 

 and it is no wonder if it gives a green to the 

 syrup of violets. No other solution has this 

 effect. 



We cannot conceive any earth to be contained 

 in any water in a separate state, unless it is 

 suspended in the form of quick-lime. A nice 

 test of this is the solution of lead in the nitric 



