Page:Popular Science Monthly Volume 25.djvu/74

66, perhaps, that the amount of water associated with the actual starch varies, producing some small differences of density or other physical variations.

Taking arrowroot as an example. To the chemist arrowroot is starch in as pure a form as can be found in nature, and he applies this description to all kinds of arrowroot; but, looking at the "price current" in the "Grocer" of the current week (February 16th), I find, under the first item, which is "Arrowroot," the following: "Bermuda, per pound. 1s. to 2s."; "St. Vincent and Natal, 2d. to 8d."; and this is a fair example of the usual differences of price of this commodity. Nine farthings to ninety-six farthings is a wide range, and should express a wide difference of quality. I have on several occasions, at long intervals apart, obtained samples of the highest-priced Bermuda, and even "missionary" arrowroot, supposed to be perfect, brought home by immaculate missionaries themselves, and therefore worth three and sixpence per pound, and have compared this with the twopenny or threepenny "St. Vincent and Natal." I find that the only difference is that, on boiling in a given quantity of water, the Bermuda produces a somewhat stiffer jelly, the which additional tenacity is easily obtainable by using a little more twopenny (or I will say fourpenny, to allow a good profit on retailing) to the same quantity of water. Putting it commercially, the Natal, as retailed at fourpence per pound, and the Bermuda at its usual retail price of three shillings, I may safely say that nine ounces of Natal, costing twopence farthing, is equal to eight ounces of Bermuda, costing eighteen-pence. Both are starch, and starch is neither more nor less than starch, unless it be that the best Bermuda at three shillings per pound is starch plus humbug.

The ultimate chemical composition of starch is the same as that of cellulose—carbon and the elements of water, and in the same proportions; but the difference of chemical and physical properties indicates some difference in the arrangement of these elements. It would be quite out of place here to discuss the theories of molecular constitution which such differences have suggested, especially as they are all rather cloudy. The percentage is: Carbon, 44·4; oxygen, 49·4; and hydrogen, 6·2. The difference between starch and cellulose that most closely affects my present subject, that of digestibility, is considerable. The ordinary food-forms of starch, such as arrowroot, tapioca, rice, etc., are among the most easily digestible kinds of food, while cellulose is peculiarly difficult of digestion; in its crude and compact forms, it is quite indigestible by human digestive apparatus.

Neither of them is capable of sustaining life alone; they contain none of the nitrogenous material required for building-up muscle, nerve, and other animal tissue. They may be converted into fat, and may supply fuel for maintaining animal heat, and may supply some of the energies demanded for organic work.