184 EXPERIMENT STATION. [Jan. 



contain ordinarily from 80 to 88 per cent, of water, most win- 

 ter varieties when maturing averaging perhaps abont 84 per 

 cent., the remainder of the frnit comprising the total solids. 

 The solids consist of the following substances: first, starch, of 

 which there may be 3 or 4 per cent., in growing apples; second, 

 sugars, of which there may be from 5 to 12 per cent., averaging 

 perhaps 8 or 10 per cent. The total sugars are made up of at 

 least three distinct compounds: sucrose, of which we may find 

 from none to 6 per cent. ; and a mixture of dextrose and levu- 

 lose, of which there may be from 5 to 10 per cent. These two 

 latfer sugars are separated in the laboratory Avith some diffi- 

 cidty, and comparatively few figures are available to show their 

 relative proportions, but it is evident that the levulose in apples 

 is in excess of the dextrose, a condition not usually found in 

 plant substances where these two sugars occur together. Of 

 organic acid we may find from .12 to 1.50 per cent., presumably 

 as some form of malic acid. 



The foregoing solids are all soluljle in water. The insoluble 

 solids are largely of a carbohydrate nature, and consist of cellu- 

 lose and pentosans for the most part. In the chemical work 

 reported in this paper determinations of the total insoluble dry 

 matter have been made and given as insoluble solids, and consist 

 of those portions of the apple not dissolved liy hot water under 

 the conditions prescribed in the method of the Official Associa- 

 tion of Agi'icultural Chemists.^ 



Apples, particularly in the green state, contain small amounts 

 of tannin. In the work here re]:)orted no determinations of this 

 have been made, but a few analyses are available from other 

 sources, giving the percentage present. The characteristic flavor 

 and aroma of apph^'^ are due for the most part to certain esters 

 or flavoring oils. These exist in the apple in very minute quan- 

 tities, and though they are of great importance in determining 

 the value and quality of the fruit, no attempt to determine the 

 amount has ever been made, so far as the knowledge of the 

 v/riter goes. Indeed, it is probable that, owing to the minute 

 quantities present, their determination would be extremely dif- 



* United States Department of Agriculture, Bureau of Chemistry, Bulletin 107, revised. 



