These are obtained in a similar manner to the oils, with a high narrow-necked still, and differ from them by the oil being retained or united with the water. Plants for this purpose should be gathered fresh on a dry day, as the water drawn from them in this state is more aromatic when they are dry; for the oil is mixed with an aqueous fluid in the plant, which concretes and separates in drying.

Herbs should be bruised and steeped for a day in about three times their quantity of water when green, but considerably more when dry; but at all times sufficient water should be added that some may be left to prevent the herbs or flowers being burnt to the bottom of the still. After all the water is drawn, the distillation should continue so long as any taste or smell of the ingredients comes over; and the fire should be so regulated that the water may run in a small continued stream.

. If a superior article is required, it must be re-distilled by a gentle heat, with the addition of a little pure spirit (about one-twentieth part) which has not got any bad smell.