Normal Institute 1589 



color tlio soil shows acidity. The more quickly the paper changes 

 and the deeper the pink color becomes, the more acid is the soil. 

 In order to make sure that the materials used — the blotting paper 

 and water — are not acid or alkaline, pnt in the bottom of the 

 tnmbler a piece of bine litmns paper and also a piece of red litmns 

 paper. Then on this j^lace the blotting- paper as before. Ponr on 

 some water, the same as is used in moistening the soil. If either 

 of the litmns papers is changed at all in color, then the paper or 

 the water cannot be used ; if the blue paper changes to red then the 

 water or the paper is acid — if the red paper becomes blue, the 

 paper or water is alkaline. Only paper and water which are neither 

 acid nor alkaline can be used. 



VARIOUS FORMS OF PLANT FOOD 



There are three general sources of artificial nitrogen. Calcium 

 nitrate or lime nitrate represents one class; ammonia represents 

 the second ; and cyanamide represents the third. 



The nitrogen in fertilizers from waste materials such as leather 

 scraps, hair, rags, etc., is, by modern methods, made available. 



* Artificial nitric acid is being manufactured in increasingly 

 large quantities from the air. The nitrogen of the air and oxygen 

 are brought together by electric energy at a high temperature and 

 the nitric acid is formed. It is believed that this will be an im- 

 portant source of commercial nitrate within five or ten years. It 

 is combined with lime instead of sodium. 



* Ammonia. A factory is now being built in Germany for the 

 commercial production of ammonia. The method is to take the 

 gases nitrogen and hydrogen and bring them into contact with 

 iron which is heated to a certain temperature. The result is liquid 

 ammonia. The materials are all very cheap. This manufacture 

 can be carried on independent of cheap water power. One ad- 

 vantage of the production of ammonia is that, when ammonia can 

 be produced almndantly and nitric acid is already available, the 

 two can be combined to make ammonium nitrate. In this com- 

 pound half of the nitrogen is in the form of ammonia and half in 

 the form of nitric acid. It would mean 35 pounds in every 100 

 pounds of material instead of 10 to 15. 



* Note. — Tliis matte- for benefit of workers but not necessary to use unloss the 

 point is brought up. 



