Minimum 00012 gram per 100 c.c. in No. 1 (calculated as acetic acid); maximum 0 0360 in No. 7. The acid is chiefly volatile acid.

Spirits from pot-still distilleries.

Other particulars of these spirits are: -

The acidity was mainly, and in some cases entirely, due to volatile acid.

A comparison of the foregoing analyses shows very clearly the broad distinction between the "pot-still " and the "patent-still" spirits. There is always a much larger amount of the secondary constituents in the pot-still spirit.

Speaking generally, the proportion of every one of the secondary constituents usually determined is greater in the "pot" than in the "patent" spirit, but the most marked differences are in the higher alcohols and furfural. Patent-still spirit contains no furfural when new, although after storage in wooden casks it is sometimes found to contain traces of this substance, but always in much smaller amount than in pot-still spirit, from which it is never absent. The low proportion of higher alcohols and the absence of all but mere traces of furfural render it a comparatively easy matter to distinguish "patent." from "pot-still" spirit. But the variation in the amounts of the secondary constituents in both classes of spirits makes it less easy to estimate the exact proportion of each kind of spirit present in mixtures.

Comparing the pot-still whiskies among themselves, it will be observed that there are considerable variations in both the total amount and in each constituent of the secondary bodies. The Scotch whiskies generally show a somewhat less total amount than the Irish, and the Speyside, Banffshire, and Highland samples have a rather smaller amount than the Islay and Campbeltown specimens. The latter, as well as the Irish samples, are mainly "blending," as distinguished from "self" whiskies.

The differences between new and old pot-still whiskies, so far as shown by analysis, are mainly in the increased amounts of the volatile acids and aldehydes, and to a less extent of the esters, found in the old spirit when stored in wooden casks. The higher alcohols and furfural show relatively much smaller differences.

Highly rectified (patent-still) spirits of high strength.

Other particulars: -

Alcohol

From 95 to 965 per cent. by volume, = 1666 to 1690 per cent. of proof spirit.

These spirits, it will be seen, are of much higher alcoholic strength than those in the two foregoing series, and contain in general still less of the secondary constituents than do the patent-still whiskies. They are not usually stored in wooden casks, but in metal drums or vats, and are used mainly for technical. and industrial purposes. They are often of very great purity, although generally made from molasses, potatoes, and beetroot-sugar residues, or other materials not employed in making spirits intended for consumption in this country.

Ordinary public-house whisky, as sold in the working-class neighbourhoods of the principal towns in the United Kingdom, is usually either patent-still spirit, or a blend of patent. and pot-still spirits containing not more than one-third of the pot-still variety. Out of 91 samples purchased and examined officially,1

Sixteen were adjudged to be probably entirely patent-still spirits;

Thirty-six were considered to contain not more than 10 per cent. of pot-still spirit; and

Sixteen contained not more than one-third of the pot-still product.

Only nine of the samples were deemed to be probably pure pot. still spirit: these were all obtained from Ireland, and formed 30 per cent. of the total number (30) purchased in that country.

A few of the analyses are appended (p. 449), as regards the secondary constituents.

The average proportions of the chief secondary constituents in various classes of spirits were found by E. A. Mann to be as follows.2 They are deduced from the analyses of 177 samples: -