This section is from the book "Manual Of Useful Information", by J. C Thomas. Also available from Amazon: Manual of useful Information.
Potatoes are an agreeable and wholesome food, and yield nearly as much nourishment as any of the roots used in diet. The farinaceous or mealy kind is in general the most easy of digestion, and they are much improved by being roasted or baked. They ought always to be eaten with meat, and never without salt. The salt should be boiled with them. Green peas and beans, boiled in their fresh state, are both agreeable to the taste and wholesome, being neither so flatulent, nor so difficult of digestion, as in their ripe state; in which they resemble the other leguminous vegetables. French beans possess much the same qualities; but yield a more watery juice, and have a greater disposition to produce flatulence. They ought to be eaten with some spice. Salads, being eaten raw, require good digestive powers, especially those of the cooling kind, and the addition of oil and vinagar, though qualified with mustard, hardly renders the free use of them consistent with a weak stomach. Spinach affords a soft lubricating aliment, but contains little nourishment. In weak stomachs it is apt to produce acidity, and frequently a looseness. To obviate these effects, it ought always to be well beaten, and but little butter mixed with it.
Asparagus is a nourishing article in diet, and promotes the secretion of urine; but in common with the vegetable class, disposes a little to flatulence. Artichokes resemble asparagus in their qualities, but seem to be more nutritive, and less diuretic. Cabbages are some of the most conspicuous plants in the garden. They do not afford much nourishment, but are an agreeable addition to animal food, and not quiet so flatulent as the common greens. They are likewise diuretic, and somewhat laxative. Cabbage has a stronger tendency to putrefaction than most other vegetable substances; and, during its putrefying state, sends forth an offensive smell, much resembling that of putrefying animal bodies. So far, however, from promoting a putred disposition in the human body, it is, on the contrary, a wholesome aliment in the true putrid scurvy. Turnips are a nutritious article of vegetable food, but not very easy of digestion, and are flatulent. This effect is in a good measure obviated by pressing the water out of them before they are eaten. Carrots contain a similar quantity of nutritious juice, but are among the most flatulent of vegetable productions. Parsnips are more nourishing and lesss flatulent than carrots, which they also exceed in the sweetness of their mucilage.
By boiling them in two different waters, they are rendered less flatulent, but their other qualities are thereby diminished in proportion. Parsley is of a stimulating and aromatic nature, well calculated to make agreeable sauces. It is also a gentle diuretic, but preferable in all its qualities when boiled. Celery affords a root both wholesome and fragrant, but is difficult of digestion in its raw state. It gives an agreeable taste to soups, as well as renders them diuretic. Onions, garlic and shallots are all of a stimulating nature, by which they assist digestion, dissolve slimy humors, and expel flatulency. They are, however, most suitable to persons of a cold and phlegmatic constitution. Radishes of all kinds, particularly the horse radish, agree with the three preceding articles in powerfully dissolving slimy humors. They excite the discharge of air lodged in the intestines.
 
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