190 OUTLINE OF CHEMICAL STUDY 



Experiment 117. Dissolve the following substance^ in equal 

 volumes of water : common salt, sugar, sal ammoniac, ammonium 

 nitrate, magnesium sulphate, and calcium sulphate. Note how 

 much of each can be dissolved in the water. Which are the more 

 soluble ? 



Which of these substances are soluble in water: HC1, oil, 

 alcohol, kerosene, molasses, mercury, and NH 4 OH ? 



Experiment 118. Into two equal volumes of water put equal 

 quantities of sugar. Stir one and allow the other to stand quietly. 

 Which dissolves more rapidly ? 



Again try to dissolve two equal quantities of sugar in equal 

 volumes of water, one cold and the other heated. Try to dissolve 



some lead chloride (PbCl 2 ) in 

 cold water in a test tube ; now 

 heat the water (Fig. 129) and 

 note the result. Does heating 

 help in dissolving solids ? 



Some substances are 

 much more soluble than 

 others, when put into the 

 FIG. 129 ^ /|f/ same liquid ; and many 

 that will not mix with one 



solvent will dissolve in another. Of the solvents, water 

 is the most common and important. Many salts, acids, 

 and bases are soluble in it, besides some other substances. 

 For this reason water is widely used as a cleansing agent. 

 Alcohol is also a common solvent ; tinctures and essences 

 are solutions of different things in alcohol, and its use 

 in medicines is important. Many of the fats and oils 

 are soluble in the alkalis, such as NH 4 OH, NaOH, and 

 KOH. Mercury dissolves several of the metals, forming 

 amalgams. Ether, turpentine, and carbon disulphide are 

 also used as solvents for certain substances. 



