“Volumetric Liquid Dosing”, Psychonaut Wiki (, , ; backlinks; similar)⁠:

Volumetric dosing is the process of dissolving a compound in a liquid to make it easier to measure. In the interest of harm reduction, it is important to use volumetric dosing with certain compounds that are too potent to measure with traditional weighing scales. This technique makes it possible to use a cheap $40.68$302013 scale and still measure accurately to a few milligrams.

Many psychoactive substances, including benzodiazepines and certain psychedelics, are active at less than a single milligram. Such small quantities cannot be accurately measured with common digital scales, so the drug must instead be dosed volumetrically by weighing out larger amounts of the compound and dissolving it in a calculated volume of a suitable liquid.