SCIENCE AND PRACTICE. 



277 



taken as 100 millions, those of some of the concentrated 

 solutions are as follows : 



1. Concentrated solution of sulphate copper, specific gravity 



= 1-1707 at 9 C 



2. Concentrated solution of sulphate zinc, specific gravity = 



1-441, at 14-4 C ; 



3. Concentrated solution of chloride sodium, at 9 '5 C 



4. Concentrated solution of chloride copper, specific gravity 



= 1-4308, at 9-25C , 10*35 



5. Concentrated solution of nitrate copper, specific gravity, 



=1-5790, at 10 C 8-40 



A striking property of sulphuric acid is that when diluted 

 to a certain point it attains its maximum conducting power ; 

 this point is when the solution has a specific gravity of about 

 1-215, or when 100 parts, by weight, of the solution contain 

 29 -6 parts of acid, after which its conducting power again 

 diminishes, as appears by the following table of some of 

 Saweljev's determinations given by Wiedemann in his 

 elaborate treatise : 



5-42 



5-77 

 31-52 



