136. (1) For the purpose of this Act the strength, weight or volume of spirits shall be ascertained in accordance with the provisions of this section.

(2) Spirits shall be deemed to be at proof if the volume of the ethyl alcohol contained therein made up to the volume of the spirits with distilled water has a weight equal to that of twelve-thirteenths of a volume of distilled water equal to the volume of the spirits, the volume of each liquid being computed as at 10.55 degrees Centigrade.

(3) The expressions "degree of proof", "degree over proof" and "degree under proof" shall be construed by reference to a scale on which one hundred degrees denotes the strength of spirits at proof, and -

(a) one hundred and one degrees, or one degree over proof, denotes the strength of spirits which would be at proof if there were added thereto such quantity of distilled water as would increase by one per cent the volume of the spirits computed as at ten degrees Centigrade;

(b) ninety-nine degrees, or one degree, under proof, denotes the strength of spirits which would be at proof if there were removed therefrom such quantity of distilled water as would reduce by one per cent the volume of the spirits computed as at ten degrees Centigrade,

and so in proportion for any other number of degrees.

(4) The equivalent at proof of spirits not at proof shall for the purposes of this Act be deemed to be their volume -

(a) multiplied by the number of degrees of proof representing their strength; and

(b) divided by one hundred.

(5) The Commissioner may make regulations prescribing the means to be used for ascertaining for any purpose the strength, weight or volume of spirits, and any such regulations may provide that in ascertaining for any purpose the strength of spirits any substance contained therein which is not ethyl alcohol or distilled water may be treated as if it were, and different regulations may be made for different purposes.

(6) This section shall apply to denatured spirits and fermented liquor as it applies to spirits.