A similar piece is illustrated in Li Yi-hua et al, Qing Porcelain of Kangxi, Yongzheng and Qianlong Periods from the Palace Museum Collection, Hong Kong, 1989, p.365.

The inscription may be translated as follows:
Standing on Cold Spring Pavilion and Composing a Song on Gathering Tea Leaves Before drying, the tea leaves are fine and tender; when dried, the tea is of sophisticated quality Longjing tea from the West Lake has an excellent reputation; when one looks at it and tries some, its superb 'way' (dao) becomes clear immediately After work, the villagers heel down the mountain slope Undried, the tea leaves looked like sparrows' tongues - dried, they look like eagles' claws The fire in the stove burns on and on, without the firing material ever running out; the leaves are being stirred continuously, and, starting with low heat, there are different grades of heat This kind of skill is rare indeed; and so for example, not many know the great Luonu Tea of Wang Su Lu Yu's Tea Classic is very detailed and often discussed Even I, who does not look for the finest sorts of tea, also treat it with great respect, as if being afraid of opening something especially wonderful Looking at the villagers picking tea-leaves, I realize just how difficult it (the process of making tea) is Inscribed by Imperial command of the Qianlong Emperor.
Two seals, qian and long