THEORY OF ELECTROLYTIC DISSOCIATION, ETC. 189 



3. A solution of boric acid, or of a boratc acidulated with dilute 

 hydrochloric acid, colors a strip of t turmeric paper dark red, which 

 becomes more intense on drying. The color is changed to bluish black 

 by dilute ammonia water. 



Sodium perborate, NaBO. 5 .4H. 2 O. When a mixture of 248 grammes of 

 boric acid and 78 grammes of sodium peroxide is gradually added to 2 liters of 

 cold water a crystallized compound is obtained. When the latter in solution is 

 treated with the proper proportion of an acid, sodium perborate separates. It 

 is very stable when dry, but in solution it has all the properties of a solution of 

 hydrogen dioxide. It is a good antiseptic and deodorant, and may be applied 

 as a dusting-powder or in solution. 



15. THEORY OF ELECTROLYTIC DISSOCIATION, OR IONIZATION. 

 ELECTROLYSIS. DISSOCIATION THEORY APPLIED TO ACIDS, 

 BASES, SALTS, AND NEUTRALIZATION. 



Theory of Electrolytic Dissociation. 



It was observed long ago tbat aqueous solutions of certain kinds 

 of substances, of which cane-sugar is a good type, do not conduct an 

 electric current, while aqueous solutions of other substances, of which 

 common salt or hydrochloric acid is a good example, are excellent 

 conductors of electricity. Moreover, it was also observed that sub- 

 stances which conduct electricity in aqueous solution do not conduct 

 when they are dissolved in certain solvents, like benzene, ether, chlo- 

 roform, etc. This fact evidently points to the conclusion that water 

 has some peculiar action on some substances whereby they become 

 possessed of the power to conduct a current. The same kind of 

 effect is also noticed in regard to chemical behavior. For example, 

 dry hydrochloric acid gas dissolved in dry benzene neither conducts 

 electricity nor has an acid reaction on litmus, nor appreciably acts 

 on zinc, whereas an aqueous solution of the gas conducts well, has a 

 marked acid reaction on litmus, and attacks zinc vigorously. It appears, 

 therefore, that hydrochloric acid molecules in aqueous solution must 

 be in a state different from that when they are dissolved in benzene. 

 It should be noted that pure water itself is not a conductor, nor are 

 the other substances when dry, but their solutions in water conduct. 

 There are a few other liquids which show this property, but to a far 

 less extent than water does, to which this discussion will be confined. 



Substances whose aqueous solutions conduct electricity are known 

 as electrolytes, those whose solutions do not are called non-electrolytes. 

 It is found experimentally that acids, bases, and salts are electrolytes, 

 and it is precisely these substances whose aqueous solutions show 



