of destroying the offensive smell of other substances, by means of the caromel formed. Sugar, also, when mixed with various bodies, and struck with a hammer, will produce detonations. Sugar, when used in compositions of fire, should be pure; and it may be known to be so, by producing invariably a phosphorescence in the dark, when two pieces are rubbed together. At a red heat, it bursts into flame with a kind of explosion. This flame is white, with blue edges. Sugar is obtained from the sugar-cane; from the sap of the sugar-maple; from beets and grapes; and from various other saccharine bodies. It is formed also artificially, by the action of sulphuric acid on starch. Mr. Kirchoff, a Russian chemist, accidentally discovered that starch may be changed into sugar by diluted sulphuric acid. One hundred parts of starch yield one hundred and ten of sugar. It appears, that, by the abstraction of a little hydrogen and carbon, starch will be converted into sugar. Potatoes, digested with diluted sulphuric acid, Dr. Ure found, would also form sugar, and very abundantly. The sulphuric acid may be removed by the addition of chalk, and, as the sulphate of lime is but slightly soluble, the pure saccharine fluid may be obtained by filtration. The sugar is procured in a solid state by evaporation, and may be clarified like other sugar. Dr. Ure observes, that good beer has been made from starch-sugar, but recommends potato-sugar. To obtain the latter, the potatoes are washed, grated down, and treated with the dilute acid for a day or two, at a temperature of 212°. The observations of Braconnot are interesting. He has succeeded in converting a variety of vegetable substances into gum and sugar. The conversion of wood into sugar, however remarkable it may seem, has been effected; and a pound weight of rags will, by the same process, make more than a pound weight of sugar. Rice, as it contains a large quantity of fecula, may, we have no doubt, be converted, in the same manner, into saccharine matter. When sugar is first obtained, it is impure, containing a variety of foreign substances, and more or less brown, as the Muscovado of the West India islands. It is refined, and formed into loaves, by treating its solution in water with bullocks' blood, the serum of which coagulates by heat; and, finally, by pouring the sugar, when sufficiently boiled, into conical earthen moulds, where it concretes. It is clayed, by putting a mixture of white clay and water on the sugar in each of the cones; the water from which passes through, and renders it beautifully white. The same process may be repeated; hence the single and double refined sugar. The molasses passes out from the sugar at the apex of the cone, and is received in vessels.