Spirits for industrial and domestic use are freed from the ordinary spirit duty on condition that they are denatured. Denatured alcohol pays a small statistical tax, and also an impost to cover the expense of examining samples and supervising the denaturing operations. The alcohol for denaturing must be of not less than 90 per cent. strength, and contain not more than 1 per cent. of fusel oil.

The denaturing may be "general" or "special." The " general ' denaturant is wood spirit of not less than 90° strength, and containing 25 per cent. of acetone with 2 5 per cent. of pyroligneous impurities. Ten litres of this are used for each 100 litres of the alcohol to be denatured.

Spirit denatured by this reagent is divided into two classes: -

(1) That used for general manufactures such as making varnishes, extracts, soap, and so on.

(2) That used for lighting, heating, and making " finish." - This spirit must contain, in addition to the general denaturing reagent,

05 per cent, of heavy benzine, distilling between 150° and 200°, when used for lighting and heating; and 4 per cent. of gum resin when used for "finish."

The "special" denaturing is to meet the requirements of those industries where alcohol mixed with wood spirit cannot be used. Authorised procedures1 are: -

(1) Ethers And Esters

The alcohol is mixed with 10 per cent. of the residue from a previous operation, and 10 per cent. of sulphuric acid at 66° Be., or 20 per cent. at 54° Be. The mixture is heated to a temperature of 80° for some time.

(2) Ethyl Bromide

-Seven and a-half litres of alcohol at 93° are mixed with 8 1/2 litres of sulphuric acid and 15 grams of bromine.

(3) Ethyl Iodide

Six litres of alcohol at 96°, with 4 kilograms of iodine, and 800 grams of amorphous phosphorus.

(4) Sodium Ethylate

Eight litres of absolute alcohol with 500 grams of sodium.

(5) Nitric Ester

One part by weight of nitric acid at 36° mixed with 4 parts of alcohol at 96°.

(6) Ethyl Chloride

Equal weights of alcohol at 96° and hydrochloric acid at 21° Be.

(7) Aldehyde

Mix the alcohol with 10 per cent. of sulphuric acid at 66° Be. or with 20 per cent. at 54° Be., and heat the mixture to a temperature of 80°. After the mixture has cooled, pour it on to potassium bichromate.

(8) Chloroform

The alcohol is mixed with chloride of lime in solution, as part of the process of manufacture.

(9) Collodion

Mix equal volumes of alcohol and ether, and add

6 grams of gun-cotton per litre.

(10) Chloral And Chloral Hydrate

A current of chlorine gas is passed into the alcohol. Each litre of alcohol at 95° should produce 780 grams of chloral hydrate.

Medicaments which contain alcohol after their manufacture pay the ordinary spirit duty.