The Spirits Regulations 1991

Ascertainment of original gravity after fermentation has commenced (1st method)

15.  When fermentation has commenced in any wash so that the original gravity of the wort from which the wash is made cannot be ascertained by an approved means, the original gravity may be determined in the following manner—

(a) a sample is to be taken from any part of such wash and, after first being cleared of insoluble matter in an approved manner, a definite quantity thereof by measure at the temperature of 20 degrees Celsius shall be distilled;

(b) the distillate and residue shall each be made up at the temperature of 20 degrees Celsius with distilled water to the original measure of the quantity before distillation, and the gravity of each shall be ascertained at 20 degrees Celsius;

(c) the number of degrees by which the gravity of the distillate is less than the gravity of distilled water at 20 degrees Celsius shall be deemed the spirit indication of the distillate;

(d) the degrees of gravity standing opposite to such spirit indication in the table in Schedule 2 to these Regulations added to the gravity of the residue expressed in degrees, shall be deemed to be the original gravity of the wort; and

(e) the degrees of the original gravity ascertained in accordance with paragraph (d) above shall be subject to such adjustment for volatile acidity as the Commissioners may allow.