126 HOW NATURE STUDY SHOULD BE TAUGHT 



Epsom salts (Magnesium sulphate, MgS0 4), 



2 grains. .162 grams. 

 Phosphate of lime, nearly the same as burned bones. 

 (Calcium phosphate, Ca3 (P04)2, 



2 grains. .162 grams. 

 East India saltpetre — Nitre (Potassium nitrate, KNO3), 



5 grains. .325 grams. 

 Compound of iron and chlorine (Ferric chloride, FeCl3), 



nearly i-io grain. 

 To make the food solution, two tablets are required for 

 each pint (500 ccm nearly) of water. Crush them, and be 

 sure that they are entirely dissolved, and always shake the 

 solution before using it. Keep the plants thoroughly moist- 

 ened with this, and it will supply them with both food and 

 drink. 



This is well known in all botanical laboratories. 

 It makes an ideal food for our common plants, 

 and the device solves the problem of school gar- 

 dens in which little soil can be used. Let the 

 seeds germinate in warm, moist air supplied in any 

 convenient manner, the most convenient perhaps 

 being wet cotton batting. Let the plant grow on 

 mosquito netting stretched across the top of a 

 tumbler, or other receptacle full of the solution, 

 or in sawdust, pebbles, or in almost any convenient 

 material kept wet with it. A luxurious crop may 

 be grown in brick-dust, or in an old tomato can, 

 or in a bowl filled with sand or with pulverized 

 stone from a macadamized road. All you need 

 is a receptacle for the material through which the 



