8S4 



Handbook of Nature-Study 



Frost crystals on window-pane. 

 Photo by W. A. Bentley. 



LESSON CCXXI 

 Water Forms 



Leading thought — ^Water occurs 

 as an invisible vapor in the air 

 and also as mist and rain; and 

 when subjected to freezing, it 

 crystaUizes into ice and frost and 

 snow. 



Method — The answers to the 

 questions of this lesson should, as 

 far as possible, be given in the 

 form of a demonstration. All of 

 the experiments suggested should 

 be tried, and the pupils should 

 think the matter out for them- 

 selves. In the study of the snow 

 crystals a compound microscope 

 is a great help, but a hand lens 

 will do. This part of the work 

 must be done out of doors. The 

 most advantageous time for 

 studying the perfect snow cry- 

 stals is when the snow is falling in 

 small, hard flakes; since, when 

 the snow is soft, there are many 

 crystals massed together into 

 great fleecy flakes, and they have 

 lost their original form. The 

 lessons on frost or dew may be 

 given best in the autumn or 

 spring. 



Observations — i. Place a saucer 

 filled with water near a stove or 

 radiator; do not cover it nor 

 disturb it. Place another saucer 

 filled with water near this but 

 cover it with a tight box. From 

 which saucer does the water 

 evaporate most rapidly? Why? 



2 . We hang the clothes, after 

 they are washed, out of doors to 

 dry; what becomes of the water 

 that was in them? Will they 

 dry more rapidly during a clear 

 or during a damp day? Why? 

 Will they dry more rapidly dur- 

 ing a still or during a windy day? 

 Why? Will they dry more 

 rapidly during hot or cold 

 weather? Why? 



3. Watch a teakettle of 



