461. Chemical science may, in many instances, be of great importance to the manufacturer, as well as to the merchant. The quantity of Peruvian bark which is imported into Europe is very considerable; but chemistry has recently proved that a large portion of the bark itself is useless. The alkali Quinia which has been extracted from it, possesses all the properties for which the bark is valuable, and only forty ounces of this substance, when in combination with sulphuric acid, can be extracted from a hundred pounds of the bark. In this instance then, with every ton of useful matter, thirty-nine tons of rubbish are transported across the Atlantic. The greatest part of the sulphate of quinia now used in this country is imported from France, where the low price of the alcohol, by which it is extracted from the bark, renders the process cheap; but it cannot be doubted, that when more settled forms of government shall have given security to capital, and when advancing civilization shall have spread itself over the states of Southern America, the alkaline medicine will be extracted from the woody matter by which its efficacy is impaired, and that it will be exported in its most condensed form. 462. The aid of chemistry, in extracting and in concentrating substances used for human food, is of great use in distant voyages, where the space occupied by the stores must be economized with the greatest care. Thus the essential oils supply the voyager with flavour; the concentrated and crystallized vegetable acids preserve his health; and alcohol, when sufficiently diluted, supplies the spirit necessary for his daily consumption.