But a closer analysis will bring us to the same conclusion. There are only three purposes for which a metallic currency is absolutely requisite--the payment of small amounts, the discharge of foreign liabilities, and the protection of the convertibility of the paper issues. The first of these is provided for by the silver and copper coin in the hands of the public. The second item is the more important of the remaining two. For the foreign reserve must clearly contain as much gold as is ever likely to be withdrawn from the country in one continuous drain. This has been estimated by Mr. Tooke, a very eminent practical authority, as about £12,000,000; but we think he must have overlooked the possible concurrence of a failure in some staple article of food, with the maintenance of a very heavy military expenditure abroad. Should such a combination ever arise, it would not be impossible that the drain might even exceed the limit of £12,000,000. It is more prudent therefore to err on the safe side, and assign £20,000,000 as the reserve to be maintained for such a contingency. But when these £20,000,000 have been set apart as a foreign reserve, there still remain at least a second £20,000,000 in the hands of the public; and the question arises, what proportion of these £20,000,000 is really required for securing the convertibility of the paper issues. To this enquiry the answer given by eminent bankers is, that £5,000,000 in gold would be more than sufficient to act as a basis for the present average circulation of £15,000,000, and that if that average were increased to £30,000,000, a gold basis of £10,000,000 would still be sufficient to secure the convertibility of the whole. And in confirmation of the truth of this view, the cases of Ireland and Scotland may be referred to, as in both, the paper circulation is considered to exceed the gold currency in about a three-fold ratio. When this domestic reserve of £10,000,000, therefore, is added to the foreign reserve of £20,000,000 there still remain at least £10,000,000 of gold that serve no necessary purpose as currency, and which it would be profitable to replace by paper.