26 EFFECTS OF 



without undergoing any chemical change, 

 they are said to be mixed; but when the 

 natural properties of each are altered by 

 the union, then those ingredients are said 

 to be combined. 



Q. Give me an example. 



A. If different coloured sands be 

 shaken together in a bottle, the various 

 grains will mix together, but not combine : 

 but if water be poured on quick lime, the 

 water will combine with the lime, and not 

 mix with it. 



Q. Why are the different grains of sand said 

 to be MIXED, when they are shaken together ? 



A. Because they are mingled toge- 

 ther, but the property of each grain 

 remains the same as it was before. 



Q. Why is water poured on lime, said to 

 COMBINE with it ? 



A. Because the properties, both of the 

 water and the lime, are altered by the 

 mixture : the lime alters the character of 

 the water, and the water alters the 

 character of the lime. 



Q. Do oxygen and nitrogen COMBINE, or only 

 MIX together, in common atmospheric air ? 



