I. I KKTII.I/.KKS 



137 



■rem wiili chlorine, end ia blow properly called potaa- 



uum chloride. It i> one of the beat known potassium 



fertilisers, and contains about 50 per cent of potash. . 



4. Sulphate of potash ia i compound of potaaaium 



with sulphur and oxygen, and i> alao manufactured 

 from tin- crude potash .-alt-. It contains about the 



saint' amount of potash as the muriates, and is much 

 used as a fertilizer. 



Questions 



1. What are commercial fertilizers? 2. Into what three 

 classes may they be divided? 3. What two inorganic sub- 

 stances supply nitrogen compounds for fertilizers? 4. Why 

 is nitrate of soda called Chile saltpetre? 5. When is nitrate 

 of soda suitable for plant food? 6. Tell what you know 

 about sulphate of ammonia. 7. How is cottonseed-meal 

 obtained from cottonseed? 8. About how much nitrogen 

 does cottonseed-meal contain? 9. With what other valu- 

 able compound does it supply the soil? 10. Name four 

 other organic substances used to supply nitrogen. 1 1 

 what country do most potash salts come? 12. Name 

 two of the crude products, and tell how much potash each 

 contains. 13. What is muriate of potash, and how much 

 potash does It contain? 14. What is sulphate of potash, 

 and how much potash does it contain? 



