70 



Phosphorus and Oxygen* 



Phosphorus unites with oxygen in two proper* 

 tions, forming phosphorous acid, which contains the 

 lowest proportion of oxygen ; and phosphoric acid, 

 which contains the greatest proportion. 



Phosphoric acid may be made by the rapid com- 

 bustion of phosphorus in oxygen j but it is usually 

 obtained from calcined bones, by decomposing 

 them with sulphuric acid. 



Phosphorus has the property of de-oxidizing se- 

 veral metallic solutions, as those of gold, silver, 

 copper, mercury, lead, tin. If a stick of phospho- 

 rus be left in a concentrated solution of nitrate of 

 copper, the copper wall be precipitated upon the 

 phosphorus in a metallic state. 



It also combines with lime, forming phosphu- 

 ret of lime. When pieces of phosphuret of lime 

 are dropt into water, flashes of fire are seen 

 to rise out of the water, which is occasioned 

 by the phosphuret decomposing the water, and 

 part of the phosphorus uniting to the hydrogen 

 gas, forming phosphuretted hydrogen gas, de- 

 scribed before. 



The phosphurets of barytes and strontia have 

 similar properties. 



J^hosphorus combines with chlorine and with io- 

 dine j and also with sulphur and the metals. Its 

 union with hydrogen has been already noticed as 

 phosphuretted hydrogen gas. 



BORAX. 



This elementary substance is known only in 

 the boracic acid, which consists of it united to 

 oxygen. 



