LABORATORY EXERCISES 151 



15. Complete the following reaction which takes place in the 

 manufacture of acid phosphate: 



Ca 3 (PO 4 ) 2 +2H 2 SO 4 +2H 2 O=? 



The resulting mixture is acid phosphate. About what proportion 

 of it is land plaster or gypsum? 



16. A 2, 8, 10 fertilizer contains what per cent of NH 3 ? Of P? 

 Of K? 



17. Muriate of potash that is 80 per cent pure (80 per cent KC1) 

 would be stated as what per cent potash (K 2 O)? 



18. Nitrate of soda that is 96 per cent pure would contain what 

 per cent of N? 



LABORATORY EXERCISES 



48. Examination of Fertilizers. 



Materials. Small samples of different fertilizing materials. 

 Describe each. Test each with litmus paper, to see which are acid 

 and which are alkaline. 



49. Absorption of Manure by Soils. (For humid regions.) 



Materials. One quart of barnyard manure, can of soil, perforated 

 bottom. 



Let the manure soak in water for a day or two, to get manure-water. 

 Pour this through the soil. Compare with the water that comes out 

 at the bottom. 



50. Losses of Manure. 



Materials. Two hundred pounds or more of manure, scales. 

 Weigh the manure, leave it in a pile outdoors for several months; 

 weigh again. 



61. Mixing Fertilizers. 



Materials. Fifty pounds or more of several fertilizing materials. 

 Mix these in the proper proportions for problem 10 or 11. 



62. Fertilizer Trial. 



Materials. One-fourth acre or more of farm land; separate ingredi- 

 ents for fertilizers. 



Lay off the field into plots one-fortieth, one-twentieth, or ones- 



