26 THE ELEMENTS OF PLANT FOOD 



Sulphuric acid, H 2 SO 4 , uniting with the bases pro- 

 duces the salts called sulphates. Write the reaction 

 for forming the following salts : potassium sulphate 

 (K 2 SO 4 ), sodium sulphate (Na 2 SO 4 ), and calcium sul- 

 phate (CaSO 4 ). 



Hydrochloric acid (HC1) will produce salts, called 

 chlorides, when combined with bases. 



Write reactions and give names for NH 4 C1, KC1, 

 NaCl, and CaCl 2 . 



Note. The following word endings and prefixes may aid stu- 

 dents in understanding some chemical terms : 



The ending ic means ordinary or common, as PC1 S is phosphor/V 

 chloride and HNO 3 is nitr/V acid. 



The ending ous means less, PC1 3 , phosphorous chloride, means less 

 of the chlorine than in phosphor/V chloride, and HNO 2 , mtrous acid, 

 less of the oxygen than in nitr/V acid. 



The prefix hydro means hydrogen and no oxygen, as in HC1, hydro- 

 chloric acid. 



The ending ide is used for compounds made up of but two elements 

 or one element and a radical, as in NaCl, sodium chloride, and KOH, 

 potassium hydroxide. Hydro-ic acids yield salts ending in ide, other 

 ic acids yield ate salts, and ous acids yield ite salts. 



Protein 



Crude Protein. - - The nitrogenous organic com- 

 pounds of plant and animal life are very complex, and 

 the terms used in describing them have been very 

 loosely applied. Crude protein is the term used to in- 

 clude all the nitrogenous matter in foods; of these sub- 

 stances the proteins are the most valuable. 



Proteins are compounds of nitrogen with carbon, 

 hydrogen, oxygen, and sulphur. The exact formula has 

 not been determined in every case. The proteins con- 

 tain about 16 per cent of N and less than 2 per cent 



