THE PROPERTIES OF OXYGEN. 





CHAPTER IV. 

 OXYGEN. ITS PROPERTIES AND RELATIONS TO LIFE. 



Oxygen is the most remarkable and important of all the 

 elementary substances. It is a gas. This term gas was 

 first used in the seventeenth century and is a reminder not 

 only of the origin of a great part of our present chemical 

 knowledge, but of the superstitions of the early periods of 

 chemical investigation; and of the recent emancipation of 

 chemistry from those superstitions. The early chemists, 

 known as alchemists, who believed in such notions, as the 

 existence of an "elixir" or fluid, which would make man 

 immortal ; and of a substance which could transmute all 

 the base metals to gold, and which they termed the "phil- 

 osophers stone," were surprised and alarmed by the sudden 

 explosions of their retorts, often accompanied by the violent 

 death of the experimenters, or of the sulphurous exhalation 

 and fumes which produced suffocation. They were led to 

 believe in their ignorance that these disasters were due to 

 the agency of spirits which refused to be imprisoned and 

 brought under the power of their tormentors, and burst the 

 vessels and slew the operators in revenge. The alchemists 

 therefore began their work with prayers and marked their 

 vessels with the holy cross from which we have had brought 

 down to us the word "crucible;" a vessel in which substan- 

 ces are subjected to great heat for the purpose of procuring 

 their decomposition. Hence we have the origin of the 

 terms spirits ; as spirits of wine, spirits of nitre, etc., and al- 

 so the term gas ; which was derived from the German gahst , 

 a ghost or spirit. 



Oxygen is a recent discovery, having been first discovered 

 in 1774 by Dr. Priestly. Its discovery was claimed by the 

 French chemist Lavoisier; but the honor is generally ac- 

 corded to Priestly. Its discovery, like all others of that and 



