Sugar and molasses from the grape, were also shown from Spain, Tunis and the Zollverein.

Sugar, or sugar candy, has been made in China from very remote antiquity, and large quantities have been exported from India, in all ages, whence it is most probable that it found its way to Rome.

The principal impurities to be sought for in cane sugar are inorganic matter, water, molasses, farina, and grape, or starch sugar.  The latter substance is occasionally, for adulterating purposes, added in Europe to cane sugar; it may be detected by the action of concentrated sulphuric acid and of a solution of caustic potassa; the former blackens cane sugar, but does not affect the starch sugar, while potassa darkens the color of starch sugar, but does not alter that of cane sugar.  But the copper test is far more delicate.  Add to the solution to be tested, a few drops of blue vitriol, and then a quantity of potassa solution, and apply heat; if the cane sugar is pure, the liquor will remain blue, while, if it be adulterated with starch sugar, it will assume a reddish yellow color.

Inorganic matter is determined by incineration, farina by the iodine test, water by drying at 210 deg., and molasses by getting rid of it by re-crystalization from alcohol, as also by the color and moisture of the article.

The natural impurities of sugar are gum and tannin; gum is detected by giving a white precipitate with diacetate of lead, and tannin by giving a black coloration or precipitate with persulphate of iron.

An experienced sugar dealer easily judges of the value of sugar by the taste, smell, specific gravity, moisture and general appearance.

The value of molasses may be determined by drying at 220 degs., and by the taste.

The commercial demand for sugar is mainly supplied from the juice of the cane, which contains it in greater quantity and purity than any other plant, and offers the greatest facilities for its extraction.

Although sugar, identical in its character, exists in the maple, the coco-nut, maize, the beet root, and mango, and is economically obtained from these to a considerable extent, yet it is not sufficiently pure to admit of ready separation from the foreign matter combined with it, at least by the simple mechanical means, the ordinary producers usually have at command; unless carried onto a large extent, and with suitable machinery and chemical knowledge and appliances.

The different species of commercial sugar usually met with in this country, are four, viz:—­brown, or muscovado sugar (commonly called moist sugar); clayed sugar, refined or loaf sugar, and sugar candy; these varieties are altogether dependent on the difference in the methods employed in their manufacture.