Vegetable Substances. 277 



collect it in large quantities from the flowers of 

 plants. Honey, however, differs iu some re- 

 spects from pure sugar ; for besides sugar it con- 

 tains mucilage and an acid. The sugar obtained 

 in the usual way, and from honey, produces, 

 when treated with the nitric acid, the oxalic acid, 

 or acid of sorrel, which is composed of 



77 parts oxygen. 



13 carbon. 



10 hydrogen. 



100 



Thus we see that the same ingredients enter 

 into the composition of this acid as into that of 

 sugar itself, but in different proportions. In the 

 oxalic acid it appears that the oxygen is in suf- 

 ficient abundance to give it the acid character. 

 This it probably in part obtains from the nitric 

 acid used in the process. 



2. Gum is a substance too well known to re- 

 quire any description. It is produced by several 

 fruit-trees, even in this country ; but that which 

 is most plentiful in commerce, under the name 

 of gum arabic, is the product of a species of mi- 

 mosa. 



Gum is found to consist of five ingredients : 

 oxygen, hydrogen, carbon, nitrogen, and lime j 

 but these may be supposed to vary in different 

 kinds. The species of gum at present known 

 are four: gum arabic, gum tragacanth, cherry- 



