offered at a price which, together with that of the gas, repays the expenses with the ordinary rate of profit. Suppose, too, that at the price put upon the gas and coke respectively, the whole of the gas finds an easy market, without either surplus or deficiency, but that purchasers cannot be found for all the coke corresponding to it. The coke will be offered at a lower price in order to force a market. But this lower price, together with the price of the gas, will not be remunerating: the manufacture, as a whole, will not pay its expenses with the ordinary profit, and will not, on these terms, continue to be carried on. The gas, therefore, must be sold at a higher price, to make up for the deficiency on the coke. The demand consequently contracting, the production will be somewhat reduced; and prices will become stationary when, by the joint effect of the rise of gas and the fall of coke, so much less of the first is sold, and so much more of the second, that there is now a market for all the coke which results from the existing extent of the gas manufacture.
Or suppose the reverse case; that more coke is wanted at the present prices, than can be supplied by the operations required by the existing demand for gas. Coke, being now in deficiency, will rise in price. The whole operation will yield more than the usual rate of profit, and additional capital will be attracted to the manufacture. The unsatisfied demand for coke will be supplied; but this cannot be done without increasing the supply of gas too; and as the existing demand was fully supplied already, an increased quantity can only find a market by lowering the price. The result will be that the two together will yield the return required by their joint cost of production, but that more of this return than before will be furnished by the coke, and less by the gas. Equilibrium will be attained when the demand for each article fits so well with the demand for the other, that the quantity required of each is exactly as much as is generated in producing the quantity required of the other. If there is any surplus or deficiency on either side; if there is a demand for coke, and not a demand
