POTASSIUM AND SODIUM. 221 



307. Ammonium Salts. This hypothetical metal forms a 

 whole series of important salts. Thus we have ammonium 

 sulphate, ammonium nitrate, which was used in the prepa- 

 ration of laughing-gas, ammonium phosphate, ammonium 

 carbonate, etc. This last-named salt is the common sal vol- 

 atile of the pharmaceutist, used as smelling-salts. It is so 

 volatile that it slowly passes away in the air in the form of 

 vapor. It is evolved in the decay of all animal and vegeta- 

 ble substances that contain nitrogen, and gives the peculiar 

 pungent odor to the stable and the manure heap. As pro- 

 duced in manures and brought down from the air in the 

 rain, it is a valuable agent in vegetation, and will be consid- 

 ered in this light in another part of this book. 



QUESTIONS. 



282. Why does potassium never occur native ? 283. How is potassium 

 obtained ? Write the equation showing the reaction. 281. What are the 

 properties of potassium ? Under what liquid is it kept ? 285. What hap- 

 pens when potassium is thrown into water ? Explain. 286. What is the 

 composition of caustic potash ? 287. How is it obtained ? 288. How is 

 potassium carbonate made ? What are its properties ? 289. How does 

 acetic acid act on potassium carbonate ? 290. What is saleratus ? What 

 raises bread and cake? 291. Where does saltpetre occur? How is it 

 made ? 292. Of what is gunpowder made ? Explain the chemistry of the 

 explosion. 293. Whence comes the power when gunpowder is burned? 

 Whence the noise ? 291. Mention the properties of sodium. 295. De- 

 scribe the decomposition of water by sodium. 29G. What is the most abun- 

 dant and useful compound of sodium ? What is said of it ? 297. What 

 would happen if salt were easily decomposed ? 298. Mention the principal 

 localities of salt deposits. 299. Describe the modes of obtaining salt. 300. 

 What is said of the amount of salt in different kinds of salt water? 301. 

 Name the three steps in the manufacture of carbonate of sodium. How 

 much water of crystallization does it contain ? 302. What is hydro-sodium 

 carbonate? 303. What is Glauder's-salt ? 301. What is borax, and whence 

 comes it ? What is the philosophy of its use by blacksmiths ? 305. What 

 is said of sodium nitrate ? 30G. Explain what is said of the ammonium 

 theory. 307. Name some ammonium salts. 



