Near Sunderland, it is found in flexible slabs. The principal range of hills composing this geological formation in England, extends from Sunderland on the northeast coast to Nottingham, and its beds are described as being about 300 feet thick on the east of the coal field in Derbyshire, which is near its southern extremity. On the western side of the Cumberland mountains magnesian limestone overlies the coal measures near Whitehaven. The stratification of this rock is very distinct, the individual courses of stone not exceeding in general the thickness of a common brick.
The lime resulting from the calcination of magnesian limestone appears to have an injurious action on vegetation, unless applied in quantities considerably less than common lime, when it is found to fertilize the soil. After two years, its hurtful influence on the ground seems to become exhausted, even when used in undue quantity. Great quantities of it are annually brought from Sunderland to Scotland by the Fifeshire farmers, and employed beneficially by them, as a manure, in preference to other kinds of lime. It has been unfairly denounced by Mr. Tennent and Sir H. Davy, as a sterilizer.
This rock is used in many places for building; indeed our most splendid monument of Gothic architecture, York Minster, is constructed of magnesian limestone.
MAGNESIA, NATIVE (Brucite; Guhr magnésien, Fr.; Wassertalk, Germ.), is a white, lamellar, pearly-looking mineral, soft to the touch. Spec. grav. 2·336; tender; scratched by calc-spar; affording water by calcination; leaving a white substance which browns turmeric paper; and, by calcination with nitrate of cobalt, becoming of a lilac hue. It consists of 69·75 magnesia, and 30·25 water. It occurs in veins in the serpentine at Hoboken, in New Jersey, as also at Swinaness, in the island of Unst, Shetland.
MAGNESITE, Giobertite; native carbonate of magnesia, occurs in white, hard, stony masses, in the presidency of Madras, and in a few other localities. It dissolves very slowly in muriatic acid, and gives out carbonic acid in the proportion of 22 parts by weight to 42 of the mineral, according to my experiments, and is therefore an atomic carbonate. It forms an excellent and beautiful mortar cement for terraces; a purpose to which it has been beneficially applied in India by Dr. Macleod.
MAGNET, NATIVE, is a mineral consisting of the protoxide and peroxide of iron combined in equivalent proportions. See [Iron].
MAHALEB. The fruit of this shrub affords a violet dye, as well as a fermented liquor like [Kirschwasser]. It is a species of cherry cultivated in our gardens.
MALACHITE, or mountain green, is native carbonate of copper of a beautiful green colour, with variegated radiations and zones; spec. grav. 3·5; it scratches calc-spar, but not fluor; by calcination it affords water and turns black. Its solution in the acids, deposits copper upon a plate of iron plunged into it. It consists of carbonic acid 18·5; deutoxide of copper 72·2; water 9·3.
MALATES, are saline compounds of the bases, with
MALIC ACID. (Acide malique, Fr.; Aepfelsäure, Germ.) This acid exists in the juices of many fruits and plants, alone, or associated with the citric, tartaric, and oxalic acids; and occasionally combined with potash or lime. Unripe apples, sloes, barberries, the berries of the mountain ash, elder berries, currants, gooseberries, strawberries, raspberries, bilberries, brambleberries, whortleberries, cherries, ananas, afford malic acid; the house-leek and purslane contain the malate of lime.