SATURATED SOLUTIONS. 61 



3. Changes of State due to Solution not accompanied by 

 Chemical Action. 



CHAPTER V. 



SOLUTION OF SOLIDS IN LIQUID SOLVENTS AND SEPARATION OF 

 SOLIDS FROM SOLUTION. 



If common salt or sugar be shaken up with water it gradually 

 disappears, becoming dissolved in the water, which becomes con- 

 verted into brine or syrup (as the case may be), acquiring the 

 saline taste of the salt or the sweet taste of the sugar ; the fluids 

 thus obtained are solutions of sugar or salt, or more strictly 

 speaking, " watery " or " aqueous " solutions, for other fluids besides 

 water may be used as "solvents," or menstrua, i.e., means to dis- 

 solve solids ; thus " camphorated spirits " is a solution of camphor 

 in alcohol, obtained by putting a little camphor into a bottle, half 

 filling with strong spirit, and allowing to stand with occasional 

 shaking. Similarly a bit of butter may be dissolved in ether, 

 chloroform, or turpentine, or a few grains of tallow may be dis- 

 solved in benzene or benzoline; or sulphur, or phosphorus in 

 carbon disulphide (Expts. 19 and 237). 



As a general rule, a given quantity of water or other solvent 

 will dissolve more of a particular substance when hot than when 

 cold. If you boil some water in a flask, and gradually keep 

 adding to it little by little alum, sugar, or other soluble matter 

 (preferably in tolerably fine powder), you will at first see that the 

 powder dissolves rapidly, but by and by it ceases to disappear 

 so quickly, and the liquid must be boiled awhile before the last 

 portion added will dissolve ; finally a point is reached when the 

 liquid cannot dissolve any more, when it is said to form a 

 saturated solution. 



Expt. 55. To obtain Crystals from a Saturated Solution by 

 further Evaporation. Dissolve 

 common salt in boiling water little 

 by little until the water will not take 

 up any more. Now pour the hot 

 liquid into an evaporating basin, that 

 is, a round-bottomed circular dish (fig. 

 35), made of porcelain, so as to stand F 'g- 35 - Evaporating-Dish. 

 heat, obtainable at the instrument dealers. Place it on a tripod 

 stand and heat it; the water now gradually evaporates, and as, 



