What is opium? Why was it valuable for the British?

Opium (or poppy tears, scientific name: Lachryma papaveris) is dried latex obtained from the seed capsules of the opium poppy Papaver somniferum. Approximately 12 percent of opium is made up of the analgesic alkaloid morphine, which is processed chemically to produce heroin and other synthetic opioids for medicinal use and for the illegal drug trade.

Explanation:

keeping a cash reserve because cash flow is the the movement of money through a company and if it just sits there, it wont the movement