nitrogen, free extract, 21.24; fat, 1.71.
The acid of the apple is usually considered to be malic acid, but really there are several acids mixed together. It is a mild and agreeable vegetable acid, and its presence adds much to the flavor of the fruit. The pectous and albuminous substances are those that assist in the formation of fruit jellies. Some of these substances are liquid when hot, and gelatinize on cooling; by too long boiling they lose this property of gelatinizing; hence the precaution that is taken in the making of fruit jellies not to boil the juice too long.
The subject of the ripening of fruits like the apple has been extensively studied, as has also that of the subsequent decay. According to recent researches, early varieties of apples contain little starch when picked, and do not keep well. The season, soil, and age of the tree affect the composition of the fruit. It has been shown that sugar is sure to be formed from the starch in the process of ripening, after the fruit is taken from the tree, and during the winter the cane sugar is gradually, and finally almost entirely, changed to directly-reducing sugar. The maximum sugar content is reached earlier the earlier in the season the apple ripens. Late winter varieties reach this point as late as November. There is much starch in the latter when picked, which gradually changes to sugar on keeping. This process is analogous to the ripening of the banana. This fruit is picked while green, and from it is made by the natives of South America a flour which is a good farinaceous food, and readily answers the place of the starchy grains. We are familiar with the fact that as the fruit ripens it contains large quantities of sugar, and is edible uncooked, which fact is usually not true of starchy foods.
The subject of the decay of the apple has been discussed in a very interesting way in the Popular Science Monthly for May, 1893, by Byron D. Halsted. Though chemical changes take place here, also, and the apple is finally resolved mostly into carbonic-acid gas, water, and mineral salts, yet these changes are brought about by the action of various fungi which find a soil favorable to their growth in the apple pulp.
Though apples are considered digestible and wholesome, their digestibility is much increased by cooking. This is especially true if some of the starch is not converted to sugar, for, as noted above, starch, to be readily assimilated in the system, should be cooked. There is probably no fruit that is so uniformly wholesome and so deservedly popular with all classes as the apple. The apple and pear were known in England before the conquest, and, indeed, probably before the Saxon invasion. They have been gradually "improved" from the wild crab-apple of Europe. It is stated on good authority that there is no country on the globe so well adapted to the growth of this fruit as the temperate regions of North America, and this seems to be demonstrated by the fact that the apples of the United States are superseding the native fruit in most of the civilized countries.
ANALYSES OF THE ASH OF THE APPLE.
| Sap-wood. | Heart-wood. | |
| Potash | 16.19 | 6.620 |
| Soda | 3.11 | 7.935 |
| Chloride of sodium | .42 | .210 |
| Sulphate of lime | .05 | .526 |
| Phosphate of peroxide iron | .80 | .500 |
| Phosphate of lime | 17.50 | 5.210 |
| Phosphate of magnesia | .20 | .190 |
| Carbonic acid | 29.10 | 34.275 |
| Lime | 18.63 | 35.019 |
| Magnesia | 8.40 | 6.900 |
| Silica | 1.65 | .700 |
| Organic matter | 4.60 | 2.450 |
| Totals | 100.65 | 100.535 |
ANALYSES OF APPLES.
One hundred pounds of average apples contain the following:
No. 1.
| Fiber | 3.2 | lbs. |
| Gluten, fat, and wax | .2 | " |
| Casein | .16 | " |
| Albumen | 1.4 | " |
| Dextrine | .7 | " |
| Sugar | 8.3 | " |
| Malic acid | .3 | " |
| Water | 82.66 | " |
| Error | .08 | " |
| 100 | lbs. |
No. 2.
| Nitrates | 5 | lbs. |
| Carbonates | 10 | " |
| Phosphate | 1 | " |
| Water | 84 | " |
| 100 |