The outflow of silver became more marked from 1834, after the East India Company lost its monopoly of the China trade, and the foreign free traders, hoping to get rich quickly, joined the lucrative opium trade which the Chinese had made illegal in 1799.

• 清廷早于一七九九年明令禁止输入鸦片，但自一八三四年东印度公司丧失与中国贸易的特权后，外商为图暴利，竟加入鸦片商贩行列，使中国银元外流的情况，更趋严重。