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IOWA ACADEMY OF SCIENCE 



The residue is changed to barium chloride with hydrochloric acid 

 and added to the first hydrochloric acid filtrate. These are heated 

 to boiling and the barium precipitated in the usual way with a 

 few drops of sulphuric acid. We treated the stems in the same 

 way. 



As the ash is chiefly carbonates, we found difficulty in getting 

 a constant weight, as the C0 2 would be driven off by the heat. 

 The per cent of the ash represents the mean of two or more deter- 

 minations. 



*Grown under canvas tents. 



Kind of leaf 



Per cent of 

 BaS0 4 



