Soda is chiefly employed in glass and soap manufactories. See the uses of minerals, Vol. i. No. 200. 83. _ELMS are forest-trees well known in almost every part of England. There are several species, of which, however, only three, the_ COMMON ELM (Ulmus campestris, Fig. 61,) WYCH HAZEL, _or_ BROAD-LEAVED ELM (Ulmus montana, Fig. 62,) _and_ DUTCH ELM (Ulmus suberosa), _grow in this country without cultivation_. _They are easily distinguishable from most other forest-trees, by their leaves being rough, and doubly serrated at the edge._ _Of these trees the flowers of the first are four-cleft, and have each four stamens, and the fruit is oblong: those of the second are five or six cleft, and have each five or six stamens, the fruit is roundish, and the leaves are broad; those of the third are four-cleft, and have four stamens, and the bark of the branches has a corky appearance._ The Dutch elm is grown in most parts of England. The common elm, though plentiful in Worcestershire, Middlesex, and some other southern counties, is said to be rare further north than Grantham or Stamford. The wych hazel is common in woods and hedges throughout the whole of South Britain. The use of the elm as _timber_ is chiefly confined to rough and inferior work. Implements of husbandry are almost wholly made of it; and it is employed for waggons, carts, mill-wheels, water-pipes, low-priced chairs, blocks for hat-makers, and various other purposes; and among the lower and middling classes, almost exclusively, for coffins. The preference which it has obtained for the latter purpose, is supposed to have originated in its peculiar durability in moist situations. Some of the northern writers state that, from the _inner bark_ of the elm, if stripped off in the spring, and boiled in water, a very palatable kind of beer may be brewed; and that this bark, dried and ground to powder, has, in times of scarcity, been mixed with meal to make bread. It is occasionally administered as a decoction for obstinate cutaneous complaints; and it has been proposed for use in rheumatism, dropsy, and other diseases. The young _leaves_ may be used for the feeding of silk-worms. Few trees are better adapted than the elm for planting in hedge rows, along the sides of roads, and along shady walks; but in the latter case the numerous suckers which grow up from its roots give much trouble to keep the ground clear. 84. _GENTIAN is a bitter drug, the dried root of a plant_ (Gentiana lutea) _which grows wild amongst the Alps, and in other mountainous parts of the Continent._