NITROGEN AND ITS OXIDES. 69 



phtiric, nitric, or any other acid, and you find the blue paper 

 will turn red. This is a characteristic property of acids. 

 Another and important distinction is this : all acids contain 

 hydrogen. Nitric anhydride, which has just been men- 

 tioned, contains no hydrogen, as its very name indicates ; 

 when, however, it comes in contact with water, a new body 

 is formed containing hydrogen, and this is nitric acid. The 

 hydrogen in acids may be replaced, as it is termed, by 

 metals forming new bodies called salts, as you will further 

 learn in 80. All the non- metallic elements, except hy- 

 drogen and fluorine, unite with oxygen, forming anhydrides, 

 which, dissolved in water, yield acids. 



79. Names given to Acids. Just as we have ous and ic 

 compounds of oxygen, so we have ous and ic acids named 

 in like manner from the proportion of oxygen in them (see 

 62). Thus nitric anhydride gives us nitric acid, while 

 nitrous anhydride gives us nitrous acid. The compounds 

 of sulphur and oxygen are similar ; sulphurous anhydride 

 yields sulphurous acid, and sulphuric anhydride yields sul- 

 phuric acid. The prefix hypo is used to name certain acids 

 having less oxygen than the ic or ous acid as hypophos- 

 phorus acid. 



When the acids combine with the metals with elimina- 

 tion of hydrogen, we have bodies whose names correspond 

 in a certain way to the acids whence they are derived. 

 The rule is as follows : Compounds of acids ending in ic are 

 indicated by names ending in ate, and compounds of acids 

 ending in ous are distinguished by names terminating in 

 ite. More concisely stated : ic acids form ates, ous acids 

 form ites. Examples are abundant : nitric acid forms ni- 

 trates, nitrcws acid forms nitrites; chloric acid forms chlo- 

 rates, chlorous acid forms chlorates. The termination ite 

 must never be confounded with the ending ide, as sulphide, 

 chloride, etc. ; these bodies contain no oxygen. 



