ACIDS, BASES, AND SALTS 175 



positions, as if it consisted of two distinct radicals, but it can be 

 shown to possess two independent sets of properties, one referring 

 to each radical. Thus a solution of cupric chloride in water 

 exhibits one set of properties which can be referred directly to the 

 cupric radical, and which is accordingly not peculiar to cupric 

 chloride, but is common to all cupric salts in aqueous solution. 

 To mention only two of these; (1) the color of the solution when 

 diluted with water, is blue, and (2) the addition of a base gives a 

 pale blue, gelatinous precipitate of cupric hydroxide (see equation 

 3 above). The same solution exhibits a second set of properties 

 which can be referred directly to the chloride radical and which is 

 consequently common to all chlorides. To mention only two of 

 these again; (1) when the solution is heated with concentrated 

 sulphuric acid, HC1 is evolved (see p. 126), and (2) the addition of 

 a silver salt gives a precipitate of silver chloride. 



The properties of acids (p. 131) are properties of the hydrogen 

 radical. The properties of bases (p. 167) are properties of the 

 hydroxyl radical OH. 



f A radical, then, is an atom, or group of atoms, which behaves as 



s a distinct unit in double decompositions, and which confers a defi~ 



J nite independent set of properties upon solutions of all acids, bases 



n or salts of which it forms one constituent. Simple radicals also 



V behave as separate units in displacements. 



3. Conductivity. Solutions of acids, bases, and salts in 

 water are all conductors of electricity. Acids, bases and salts 

 are therefore called " electrolytes." In all cases the solution 

 is decomposed by the passage of the current. The positive and 

 negative radicals of which the solute is composed are attracted 

 to the opposite electrodes. There, unless special circumstances 

 prohibit (see for example, the electrolysis of sodium chloride, 

 p. 139), they are liberated. Thus, all acids give hydrogen at the 

 negative pole, the other radical passing to the positive pole. 



Of all the properties they have in common, this one of being 



