312 Domestic Scieiice 



(d) Pour a little sodium hydroxide solution into 

 the solution of the salt. 



(e) Pour a small quantity of sulphuric acid into 

 the solution. 



Tabulate your results and note that the behaviour 

 of salts is less uniform than that of acids or of alkalis. 



In general, salts in solution will give a neutral 

 reaction with litmus, but some salts, such as the sodium 

 carbonate in the last experiment, have an alkaline 

 reaction, while others, e.g. copper sulphate, produce the 

 opposite effect. These exceptions are known as " salts 

 with an alkaline reaction " and " salts with an acid 

 reaction " respectively. They must not be confounded 

 with " acid " salts and " basic " salts (see later portion 

 of this chapter). 



Exercise for Student. 



Test the reaction of as many salt solutions as you can, classifying 

 them as of neutral, acid, or alkaline reaction, according to the 

 results of your tests. 



216. We have previously discussed the suitability 

 of Lavoisier's name for the element oxygen, and it 

 should be noted that all acids formed by the combina- 

 tion of an acidic oxide with the elements of water 

 do contain this element. They are known as the 

 " oxy-acids ". Sulphuric, nitric, and carbonic acids fall 

 into this group. Such an acid as hydrochloric acid 

 does not contain oxygen, being formed by dissolving 

 a compound of the elements hydrogen and chlorine- 

 hydrogen chloride in water (see Part II). The water 

 does not combine with the hydrogen chloride, as may 

 be shown by merely boiling the solution. According 

 as this be strong or weak, hydrogen chloride will be 

 evolved, making the strong solution weaker, or water 



