The profits of stock vary with the price of the commodities in which it is employed. As the price of any commodity rises above the ordinary or average rate, the profits of at least some part of the stock that is employed in bringing it to market, rise above their proper level, and as it falls they sink below it. All commodities are more or less liable to variations of price, but some are much more so than others. In all commodities which are produced by human industry, the quantity of industry annually employed is necessarily regulated by the annual demand, in such a manner that the average annual produce may, as nearly as possible, be equal to the average annual consumption. In some employments, it has already been observed, the same quantity of industry will always produce the same, or very nearly the same quantity of commodities. In the linen or woollen manufactures, for example, the same number of hands will annually work up very nearly the same quantity of linen and woollen cloth. The variations in the market price of such commodities, therefore, can arise only from some accidental variation in the demand. A public mourning raises the price of black cloth. But as the demand for most sorts of plain linen and woollen cloth is pretty uniform, so is likewise the price. But there are other employments in which the same quantity of industry will not always produce the same quantity of commodities. The same quantity of industry, for example, will, in different years, produce very different quantities of corn, wine, hops, sugar tobacco, etc. The price of such commodities, therefore, varies not only with the variations of demand, but with the much greater and more frequent variations of quantity, and is consequently extremely fluctuating; but the profit of some of the dealers must necessarily fluctuate with the price of the commodities. The operations of the speculative merchant are principally employed about such commodities. He endeavours to buy them up when he foresees that their price is likely to rise, and to sell them when it is likely to fall.