Abstract
Sale of things determined by weight, number or measure was regarded as a specific kind in Roman law. In order to establish an obligation, the object of sale had to be physically measured out, weighed or pointed out by counting.
Still, it was debated among classical lawyers when exactly does such a contract become perfect and thus binding for both contractual parties. The article attempts to pinpoint the moment of perficio emptionis of generic things using the example of a sale of wine.
Due to the character of such a thing the sources mention a special set of rules for this kind of sale that require measuring out the wine sold (mensura) and contain an option to taste the wine (degustatio) as well as to spill out the wine sold (effundere vinum). All of these may be used in the analysis of the perficio emptionis as an indication of legal effects that take place at the moment of mensura and degustatio.