247 



with this acid an insoluble compound, it will 

 always occasion in any such fluid a^visible tur- 

 bidncss, and consequent precipitation. The ni- 

 trous solution (nitrat of silver) boiled or evapo- 

 rated to a solid state, forms lunar caustic. 



A solution of nitrat of silver stains animal 

 substances of a deep black. Hence it has been 

 applied to alter the colour of red hair. On ac- 

 count of its corrosive quality, however, much 

 caution must be observed in this application, and 

 particular care taken that the solution shall be 

 sufficiently weak. 



The nitrat of silver is decomposed by other 

 metals, which precipitate it from the acid. Thus 

 if a little of a solution of the nitrate is applied to 

 a bright plate of copper, it will become plated 

 with silver. 



Upon the same principle the beautiful experi- 

 ment called Diana's tree is made. If into a 

 bottle containing a solution of nitrat of silver a 

 small quantity of mercury is poured, the sil- 

 ver will be precipitated; but as the particles 

 have still an attraction for each other, the pre- 

 cipitation will assume the form of the branches 

 of a tree. 



4-th. ^Mercury is distinguished from every 

 other metal, by having so strong an attraction 

 for caloric, that it remains fluid in the ordinary 

 temperature of our atmosphere. If our climate 

 was cold enough, it would become solid like the 

 rest of the metals. It has, indeed, been some- 



