WATER. 231 



It is a valuable article in medicine, and is employed by 

 tinmen in soldering to prevent the oxidation of copper sur- 

 faces ; also in a variety of metallurgical operations. 



Mascagnite. A hydrous ammonium sulphate. In mealy crusts, 

 of a yellowish-gray or lemon-yellow color ; translucent ; taste pungent 

 and bitter. Composition (N H 4 ) 2 4 S + Hj 0= Sulphur trioxide 53 '3, 

 ammonia 22 "8, water 23 9. Easily soluble in water. Occurs at Etna, 

 Vesuvius, and the Lipari Islands. It is one of the products from the 

 combustion of anthracite coal. 



Lecontite is hydrous ammonium-sodium sulphate. Boussingaultite 

 is a hydrous ammonium-magnesium sulphate, from Tuscany. 



Struvite. A hydrous ammonium-magnesium phosphate ; occurring 

 in yellowish crystals, slightly soluble in water ; found on the site 

 of an old church in Hamburg, where there had been quantities of cat- 

 tle dung. 



Tschermigite. An ammonia alum from Tschermig, Bohemia, and 

 Utah County, Utah. 



Larderellite. A white tasteless ammonium borate, from the Tuscan 

 lagoons. 



Hydrous ammonium phosphate and Ammonium oicaroonatc (Tesche- 

 macherite) have been detected in guano ; also, Hydrous sodium-am- 

 monium phosphate, called Stercorite. 



HYDROGEN. 

 Hydrogen is the basic constituent in hydrochloric acid, 

 and in water. 



Hydrochloric Acid. — Muriatic Acid. 



A gas, consisting of Chlorine 97*26, hydrogen 2*74=100 

 =H CI. It has a pungent odor, and is acrid to the skin. 



It is rapidly dissolved by water. If passed into a solution 

 of nitrate of silver, it produces a white precipitate which 

 soon blackens on exposure. It is given out whenever com- 

 mon salt is acted on by sulphuric acid, and occasionally by 

 volcanoes. 



WATER. 



Water (hydrogen oxide) is the well-known liquid of 

 streams and wells. The purest natural water is obtained by 

 melting snow, or receiving rain in a clean glass vessel ; but it 

 is absolutely pure only when procured by distillation. It 

 consists of hydrogen 1 part by weight, and oxygen 8 parts, 

 or hydrogen 11*11, oxygen 88'89 = 100. It becomes solid at 

 32° Fahrenheit (or 0° Centigrade), and then crystallizes, 

 and constitutes ice or snow. The crystals are of the hex- 

 agonal system. Flakes of snow consist of a congeries of 



