CHEMISTRY FOR AGRICULTURAL STUDENTS 



IX. COMPOSITION OF WATER 



Is water an element or a compound, and if the latter, what are 

 its constituents? To answer this question an attempt must 

 be made to decompose it. The effect of heat, however, which 

 has been found to decompose certain chemical compounds, is 

 simply to change its state from water to steam. No chemical 

 change occurs similar to that which resulted from heating oxide 

 of mercury, for in this, and in all the other chemical changes 

 studied, substances have been formed having entirely different 

 properties from the original substances, and the changes are 

 permanent and not simply changes of state. Possibly, however, 

 steam, like air, can act chemically on iron, charcoal, etc., 

 especially if these be heated to promote the chemical change; 



Fit up the apparatus figured, and place in the wide tube, 

 which must be constructed of hard glass, some iron fihngs 



r> 



Fig. 20 



(or, better, some iron turnings). Heat the filings to a low 

 red heat; pass steam from the flask of boiling water 

 very slowly through the tube, and lead the escaping gas or 



