Then the weight of 10000 grams of potatoes of like nature in water would be found from the equation 159: 10000 = 14.8: x.
Whence x = 931 nearly.
In the table the nearest figure to 931 is 930, corresponding to 24.6 per cent of dry matter and 18.8 per cent of starch. When the number found is half way between the numbers given in the table the mean of the data above and below can be taken. In other positions a proper interpolation can be made if desired but for practical purposes the data corresponding to the nearest number can be used.
Table for Calculating Starch in Potatoes
from Specific Gravity.
| 10000 grams of potatoes weigh in water. Grams. | Per cent dry matter. | Per cent starch. |
|---|---|---|
| 750 | 19.9 | 14.1 |
| 760 | 20.1 | 14.3 |
| 770 | 20.3 | 14.5 |
| 780 | 20.7 | 14.9 |
| 790 | 20.9 | 15.1 |
| 800 | 21.2 | 15.4 |
| 810 | 21.4 | 15.6 |
| 820 | 21.6 | 15.8 |
| 830 | 22.0 | 16.2 |
| 840 | 22.2 | 16.4 |
| 850 | 22.4 | 16.6 |
| 860 | 22.7 | 16.9 |
| 870 | 22.9 | 17.1 |
| 880 | 23.1 | 17.3 |
| 890 | 23.5 | 17.7 |
| 900 | 23.7 | 17.9 |
| 910 | 24.0 | 18.2 |
| 920 | 24.2 | 18.4 |
| 930 | 24.6 | 18.8 |
| 940 | 24.8 | 19.0 |
| 950 | 25.0 | 19.2 |
| 960 | 25.2 | 19.4 |
| 970 | 25.5 | 19.7 |
| 980 | 25.9 | 20.1 |
| 990 | 26.1 | 20.3 |
| 1000 | 26.3 | 20.5 |
| 1010 | 26.5 | 20.7 |
| 1020 | 26.9 | 21.1 |
| 1030 | 27.2 | 21.4 |
| 1040 | 27.4 | 21.6 |
| 1050 | 27.6 | 21.8 |
| 1060 | 28.0 | 22.2 |
| 1070 | 28.3 | 22.5 |
| 1080 | 28.5 | 22.7 |
| 1090 | 28.7 | 22.9 |
| 1100 | 29.1 | 23.3 |
| 1110 | 29.3 | 23.5 |
| 1120 | 29.5 | 23.7 |
| 1130 | 29.8 | 24.0 |
| 1140 | 30.2 | 24.4 |
| 1150 | 30.4 | 24.6 |
| 1160 | 30.6 | 24.8 |
| 1170 | 31.0 | 25.0 |
| 1180 | 31.3 | 25.5 |
| 1190 | 31.5 | 25.7 |
| 1200 | 31.7 | 25.9 |
| 1210 | 32.1 | 26.3 |
| 1220 | 32.3 | 26.5 |
| 1230 | 32.5 | 26.7 |
| 1240 | 33.0 | 27.2 |
| 1250 | 33.2 | 27.4 |
| 1260 | 33.4 | 27.6 |
| 1270 | 33.6 | 27.8 |
| 1280 | 34.1 | 28.3 |
| 1290 | 34.3 | 28.5 |
| 1300 | 34.5 | 28.7 |
| 1310 | 34.9 | 29.1 |
| 1320 | 35.1 | 29.3 |
| 1330 | 35.4 | 29.6 |
| 1340 | 35.8 | 30.0 |
| 1350 | 36.0 | 30.2 |
| 1360 | 36.2 | 30.4 |
| 1370 | 36.6 | 30.8 |
270. Constitution of Cellulose.—The group of bodies known as cellulose comprises many members of essentially the same chemical constitution but of varying properties. The centesimal composition of pure cellulose is shown by the following numbers:
| Carbon, | 44.2 | per | cent |
| Hydrogen, | 6.3 | ” | ” |
| Oxygen, | 49.5 | ” | ” |
corresponding to the formula C₆H₁₀H₅.
According to the view of Cross and Bevan, cellulose conforms in respect of its ultimate constitutional groups to the general features of the simple carbohydrates, but differs from them by reason of a special molecular configuration resulting in a suppression of the activity of constituent groups in certain respects, and an increase in activity of others.[221]
271. Fiber and Cellulose.—The carbohydrates of a plant insoluble in water are not composed exclusively of starch. There are, in addition to starch, pentosan fibers yielding pentose sugars on hydrolysis and furfuraldehyd on distillation with a strong acid. The quantitive methods for estimating the pentosan bodies are given in paragraphs [150-157]. The method to be preferred is that of Krug ([155]).