60 PEACTICAL FARM CHEMISTRY. 



3 H2 O represents two such molecules, and is equiv- 

 alent to 4H+20. 



The following is a list of formulas of those com- 

 pounds which chiefly interest the soil worker, viz. : 



H Cl stands for muriactic (hydrochloric) acid. 



Na CI " " common salt. 



Na CO3 " " carbonate of soda. 



Na HO " " hydrate of soda or caustic soda. 



Na2 SO4 -f-lOHg O stands for sulphate of soda (Glauber salts). 



Na NO3 stands for nitrate of soda or Chili saltpetre. 



KHO " " hydrate of potassium (caustic potash) . 



Kg CO3 " " carbonate of potash. 



K NO3 " •' nitre or saltpetre (nitrate of potash). 



K2 SO4 " " sulphate of potash. 



K2 O " " potassium oxide. 



H3 N " " ammonia. 



NO2 ** " nitrous acid 



NO3 " " nitric acid. 



NH4 Cl " " sal-ammoniac. 



NHsO " " aqua ammonia. 



CasPgOg " " phosphate of lime. 



AsgOs " " arsenious acid. 



P2 Os " " phosphoric oxide (acid). 



H2 O " " water. 



H« 8 " " sulphuretted hydrogen. 



SO2 " " sulphurous oxide. 



SO 3 " " sulphuric oxide. 



H2 SOs " " sulphurous acid. 



H2 SO4 " " sulphuric acid. 



Cu SO4 + 5H2 O stands for sulphate of copper (blue vitriol). 



Ca O stands for lime (caustic or burnt lime, quick lime). 



Ca H2 O2 " " slacked lime. 



Ca SO4 *• " sulphate of lime (plaster of Paris). 



Ca SO4 4-3H2 O stands for gypsum (land plaster). 



Ca CO3 stands for carbonate of lime. 



Mg O " " magnesia (magnesium oxide). 



Mg SO4 -\- 7H2 O stands for Epsom salts (sulphate of magnesia). 



Fe SO4 -f- 7H2 O stands for sulphate of iron (copperas). 



Si O2 stands for silica. 



CO2 " " carbonic acid. 



CH4 " "marsh gas. 



The reader may ask me: What good to us is there 



