SALTS. 



to have recourse to the atomic weights themselves 

 than to the proportions of the constituents con- 

 tained in 100 parts of the salt. To give an ex- 

 ample : 



Atom of sulphuric acid 5 



Atom of protoxide of lead 14 



Of sulphate of lead 19 



Now, the constituents of sulphate of lead per 

 cent, are 



Sulphuric acid 26-3158 



Protoxide of lead 7-3-6842 



100-0000 



Suppose I have 86 grains of sulphate of lead, 

 and that I wish to know how much sulphuric 

 acid it contains : it is easier to use the propor- 

 tion 



19 : 5 : : 86* : 22-63 = oxide of lead required, 



than the proportion 



100 : 26-3158 : : 86 : 22-63 = oxide of lead. 



or if the second process be sometimes as short as 

 the former, the former has the advantage of al- 

 ways giving a precise result, whereas the latter 

 in general is only an approximation. This has 

 induced me for sometime to abandon the old 

 mode of stating the constituents of salts in the 

 proportions contained in 100 parts of the salt, 



