Not the least of their advantages is that they contain a very large proportion of water; and this, though diminishing their fuel value, supplies the body with a naturally filtered and often distilled supply of this necessary element of life. One of the best ways of avoiding that burning summer thirst, which leads you to flood your unfortunate stomach with melted icebergs, in the form of ice water, ice cold lemonade, or soda water, is to take an abundance of fresh fruits and green vegetables. Many of the vegetables contain small amounts of starch, but few of them enough to count upon as fuel, except potatoes, which we have already classed with the Coal foods. Most fruits contain a certain amount of sugar--how much can usually be estimated from their taste, and how little can be gathered from the statement that even the sweetest of fruits, like ripe pears or ripe peaches, contain only about eight per cent of sugar. They are all chiefly useful as flavors for the less interesting staple foods, particularly the starches. In fact, our instinctive use of them to help down bread and butter, or rice, or puddings of various sorts, is a natural and proper one. Like the vegetables, they contain various salts which are useful in neutralizing certain acid substances formed in the body. Soldiers in war, or sailors upon long voyages, who are fed upon a diet consisting chiefly of salted or preserved meat, with bread or hard biscuit and sugar, but without either fruits or fresh vegetables, are likely to develop a disease called scurvy. Little more than a century ago, hundreds of deaths occurred every year in the British and French navies from this disease, and the crews of many a long exploring voyage--like Captain Cook's--or of searchers for the North Pole, have been completely disabled or even destroyed entirely by scurvy. It was discovered that by adding to the diet fruit, or fresh vegetables like cabbage or potatoes, scurvy could be entirely prevented, or cured.[10] Their Low Fuel Value. How little real fuel value fruits and vegetables have, may be easily seen from the following table. In order to get the nourishment contained in a pound loaf of bread, or a pound of roast beef, you would have to eat: 12 large apples or pears (5 lbs.); 4-1/2 qts. of strawberries; a dozen bananas (3-1/2 lbs.); 7 lbs. of onions; 2 doz. large cucumbers (18 lbs.); 10 lbs. of cabbage; 1/2 bushel of lettuce or celery.