Suggestions and Course of Study 137 



Take a spoonful of water from the surface and taste. 

 Is it sweet ? The sugar, in dissolving, has been broken 

 up into minute particles that become suspended 

 between the molecules of water. The sugar particles 

 do not remain at the bottom, but spread throughout 

 all the water till all parts are equally sweetened. 

 Would this be possible if the sugar did not dissolve ? 



IV. On Evaporation, (a) Put a strip of filter paper 

 into water; leave it exposed to the air. It dries. 

 What has happened? (6) Hold a spoon containing 

 water over an alcohol flame. The water boils and 

 disappears; what has happened? (c) Hold a mois- 

 tened strip of filter-paper near the flame and another 

 farther from the flame. The former dries more 

 quickly. What difference in the condition of the two 

 strips may account for the difference in effect ? Would 

 the sun shining on one of the strips and not on the 

 other have a similar effect? (d) Dissolve some salt 

 in a tumbler one- fourth full of water; allow the water 

 to evaporate. Has the salt evaporated? Examine 

 the crystals remaining. 



V. On the Effects of Heat, (a) Fill a tin cup with 

 snow; determine the temperature of the snow by 

 means of a thermometer. Take a spoonful of this 

 snow and hold it over the alcohol lamp. Why does 

 this snow melt while that remaining in the- cup does 

 not? (6) Stir a considerable quantity of salt into the 

 snow remaining in the cup. Does the temperature 

 remain the same? (c) Place the tin cup over the 

 alcohol flame till the snow melts. What is the tem- 

 perature of the water resulting from the melting snow ? 

 Continue to heat the water. Does the temperature 

 rise at once? (d) Determine the temperature of boil- 

 ing water, (e) Why do bubbles gather at the bottom 

 of the cup and finally begin to ascend? As the 

 bubbles burst at the surface they give rise to steam. 

 (/) Fill a little vial with water and cork tightly. 



