But to return to the history of the foreign trade. As was mentioned above, the Chinese Commissioners of their own accord fixed the tariff duty upon opium at thirty taels. But, though bound, as they were by their own act, to admit opium at this rate, as soon as it passed into native hands they had power to tax it as they pleased, and they did not fail to profit by their power, though this likin tax varied considerably at the different ports[30] in accordance with the necessities of the provincial governments. It is difficult to estimate the revenue obtained by China from the foreign opium trade, but it is probably close upon two millions sterling. That the Chinese Government were not satisfied with this amount, compared with the profits gained by India, is quite clear; and we find accordingly that various efforts were made by them, subsequent to 1869, to have the tariff agreed upon in the Treaty of Tientsin revised. But it was not till 1876 that any definite agreement was come to between the two Governments. In September of that year Sir Thomas Wade, Secretary Li, and Prince Kung concluded a convention, by which China opened four new ports[31] and six places of call on the great river, while Sir Thomas Wade agreed to recommend to his own Government, and through it to all the Treaty Powers, the limitation of the area, within which imports should be exempt from likin, to the actual space occupied by the foreign settlements. As the treaty regulations then stood, imports, except opium, after paying their regular import duty, were not liable to likin or transit dues till they reached a certain barrier at some distance inland. Opium could be taxed as soon as it left the importer's hands. But this right, which applied to opium only, had been used by the Chinese against all imports, a clear infraction of treaty which the German Consul, among others, had protested against. But as some doubt existed as to where the first inland barrier really stood, Sir Thomas Wade proposed to make the circuit of the foreign settlement the limit of exemption from duty. But foreseeing that, if the likin Collectorate were banished from the port-areas, opium would evade paying the likin tax, he proposed also to recommend that the likin, as well as the import duty, on opium should be collected by the foreign Inspectorate, and that for this purpose the opium should be bonded in a warehouse or receiving hulk till such time as the importer had paid the import due and the purchaser had paid the likin. He further proposed as a fair likin tax forty taels per picul (though certain that the Chinese did not get more than 30) on all Indian opium, that brought to Hongkong included. Thus the whole duty (import and likin) on opium would be seventy taels a picul, which would yield 6,117,930 taels, or a million more than under the old system. But the Chinese Commissioner, Prince Kung, objected to a uniform duty of forty taels, as too low, and