HOUSEHOLD CHEMICALS 



vinegar, sulphuric acid, and oxalic acid; and the second, by 

 ammonia, lye, and limewater. 



Acids. We know that vinegar and lemon juice have a sour 

 taste, ami it is easy to show that most acids are characterized 

 by a soui taste. If a clean glass rod is dipped into very 

 dilute acid, such as acetic, sulphuric, or nitric acid, and then 

 lightly touched to the tongue, it will taste sour. But the best 

 test of an acid is by sight rather than by taste, because a minute 

 trace of acid is able to discolor a plant substance called litmus. 

 If paper is soaked in a litmus solution until it acquires the 

 characteristic blue hue of the plant substance, and is then dried 

 thoroughly, it can be used to detect acids. If a drop of acid 

 substance is put upon blue litmus paper, it will change the color 

 of the paper to red. The litmus paper test shows that many 

 of our common foods, such as fruit, buttermilk, sour bread, and 

 vinegar, contain acid of some kind. The acid in lemon juice 

 is mostly citric acid ; in buttermilk, lactic acid ; and in vinegar, 

 acetic acid. 



Acids are usually in liquid form. Sometimes, however, they 

 are solid. Oxalic acid, which is so useful in the removal of ink 

 stains, is a solid. But it dissolves readily in water, and an acid 

 solution of oxalic acid is always obtainable. Tartaric acid, an 

 ingredient of some baking powders, is a solid acid. 



The damage that can be done by strong acids is well known. 

 If a jar of sulphuric acid is overturned, and some of it falls on 

 the skin, it eats its way into the flesh and leaves an ugly sore ; 

 if it falls on carpet or coat, it eats its way into the material and 

 leaves an unsightly hole. The evil results of an accident can 

 be lessened if we know just what to do and do it quickly, but 

 for this we must have a knowledge of bases, the second group 

 of chemicals. 



Bases. Substances belonging to this group usually have a 

 bitter taste and a slimy, soapy feeling. For our present purposes, 



