VEGETABLE FOOD. 265 
Various kinds of fruits, leaves, and parts of plants are preserved in 
vinegar and added to food. Some things are used in this way which are 
not otherwise employed. This is the case with the caper, which is the 
fruit of the Capparis spinosa: and the stertion, the fruit of the Indian 
cress (Tropceolum majus). A collection of fruits and plants preserved 
in vinegar will be found on the shelves devoted to the exhibition of 
"acids." 
Sugar may be converted into vinegar by the aid of vegetation. The 
so-called " Vinegar Plant," of which a specimen is exhibited in the 
Museum, is the mycelium of ,a fungus, which, during its growth in sugar 
and water, decomposes the sugar, and the result is the formation of the 
vegetable matter of the plant, and the development of acetic acid. 
The natural order Aurantiacese embraces the orange, the lemon, the 
citron, the shaddock, the pomelot, the lime, and other fruits. All of 
them contain citric acid, and varying proportions of sugar. 
The flowers of the orange yield a delicious perfume known as oil of 
Neroli. 4 ^ 
The juice of these fruits is employed in the Navy for the purpose of 
preventing scurvy amongst sailors. This effect has been attributed 
solely to the citric acid, but it has been found that the acid alone does 
not act so efficaciously as when contained in the juice of the fruit. 
Hence some writers have attributed the effect to a chemical compound 
of the acid with other ingredients of the jnice. 
Citric acid is also found in many fruits, but mixed with other acids, 
as in the berberry, strawberry, &c. 
Tartaric Acid forms with potass an insoluble salt, known by the 
name of argol, and, when purified, cream of tartar. This salt is found 
in the lees of wine. By burning it the tartaric acid is converted into 
carbonic acid, and the salt of tartar (carbonate of potash) is made from 
the tartar of wine. Hence also the name tartaric acid. The dried 
fruits of the grape (Vitis vinifera) are known by the name of " raisins " 
and " currants." 
The tomato is the fruit of the Lycopersicum esculentum, and on 
account of its acid flavour is used as a sauce. 
The edible products of the natural order Kosaceae, comprising the 
fruits of the apple, pear, apricot, nectarine, peach, cherry, plum, rasp- 
berry, strawberry, contain malic acid. They are mostly preserved in 
sugar. Many forms of plums called prunes contain a sufficient quantity 
of sugar to be dried and preserved without further preparation. — ' Guide 
to the Food Collection in the South Kensington Museum.' 
