208 NATURE STUDY AND AGRICULTURE 



Teachers should look over the lessons carefully in order 

 to plan their work successfully. Many of the experiments, 

 especially in soil physics and in the work of plants, must 

 be started several days, or in some cases weeks before 

 giving the lesson. 



A list of bulletins that contain much helpful informa- 

 tion is placed at the close of each chapter. No. 195, en- 

 titled Some Exercises Illustrating Some Applications of 

 Chemistry to Agriculture will be found especially helpful in 

 working out the lessons in soil chemistry, and No. 186, 

 Exercises in Elementary Agriculture, will be helpful in the 

 lesson- on soil physics and the work of plants. All the 

 bulletins listed may be obtained free by applying to United 

 States Department of Agriculture. 



A few pieces of apparatus are indispensable in con- 

 ducting the lessons in physical experiments in the seventh 

 grade, and in soil studies in the eighth. The following 

 list of necessary articles may be obtained at a very little 

 cost. 



Alcohol lamp. This may be made from a vaseline 

 bottle. Get the tinner to make you a small tin tube about 

 an inch and a half long. Push this through the middle of 

 the cork and punch out the cork inside the tube. Twist 

 some soft string into a wick and pull it through the tube. 

 Fill the bottle a little over half full of alcohol. Wood 

 alcohol will serve as well as grain. Turn a small vial or 

 thimble over the wick to prevent evaporation. 



A test tube. A small glass flask having a rubber 

 stopper with a hole in it. A measuring cup; a glass one 

 may be purchased for ten cents at any crockery store. A 

 thermometer. A long iron nail, a heavy piece of iron wire, 



