Although the domestic supply of hides and skins is quite inadequate to meet the needs of British tanners, a large proportion is exported. American tanners buy large quantities of the best hides and pickled sheep skins. The latter are dewoolled and preserved by a process of pickling with formic or sulphuric acid and salt before exportation. Those preliminary operations are the work of the fellmonger. Nearly all of the horse hides produced in the United Kingdom are, or were before the War, sent to Germany, and British leather-dressers appear to have lost the art of finishing horse hide, or are unable to convert it into leather profitably. The interchange of raw hides between various countries, and even between those where leather manufacture is an important industry, is somewhat remarkable, and only goes to prove that the concentration of a particular industry in one or two centres of the world gives these places a great advantage in regard to labour, organisation, and technical skill, even over those countries where the raw material is plentiful. Theoretically and economically it should be advantageous to establish tanneries close to the supply of raw hides, since the latter, under present conditions of preservation, steadily deteriorate from the time they are removed from the carcase until they reach the tannery. In some countries the methods of preserving hides are actually so bad that the hides have often lost half of their value before the tanner gets them. Two or three of the largest American meat-packing establishments have erected or taken over tanneries to deal with raw hides, one of their by-products. Tanneries have also been erected near some of the large meat works in the Argentine, but the development of the leather trade there is by no means rapid, and at present the United States of America is the largest leather-producing country in the world. Germany, France, and the United Kingdom come next in the order named.