E-pistle #18/10 – The Art of Blending Prune Wine & Whisky

By Lawrence Graham, Canada

Before legislation that guaranteed the quality of Scotch whisky, adulteration was quite common, often with a detrimental effect to the unsuspecting consumer. The fascinating book by Edward Burns, “It’s a bad thing whisky; especially BAD WHISKY”(1) neatly describes the lengths unscrupulous producers and publicans went to sell immature whisky as a mature and wholesome product.  Fusel Oil(2), to use the term of the day, was the main culprit and producers, eager to rush immature spirits (often directly off the still) to market without the costly prospect of lengthy maturation in wood, added many adulterations to the whisky in an attempt to mask the foul taste of Fusel Oil.  Fusel Oil is initially noxious and completely ruins the taste of the spirit. To counter act the practice of selling immature spirit and to improve the taste, various products were added to the whisky including sherry wine, tartaric and acetic acids, sugar, pineapple, fruit essences, tincture of prunes, acetic ether, oil of wine, spirit of nitrous ether, glycerine, green tea and other repugnant substances.

The absolute best description of Fusel Oil that I came across was from J. Emerson Reynolds, Esq., M.D., Professor of Chemistry, Trinity College; “I have always attached great importance to the practical freedom of Whisky from Fusel Oil, as the latter is an organic mixture which exerts a distinct poisonous action on the animal organism; and I am well aware that New Whisky too often contains this noxious body in comparatively considerable quantities.”

During the 1870’s ‘blending’ in reference to whisky meant the addition of non whisky ingredients rather then the mixing of malt and grain whisky as we are familiar with the term today. Prune Wine was the best of the ‘adulterations’ and was marketed as a quality product (in some cases it was a better quality product than the whisky it was destined to be ‘blended’ with). Manufactured in Ireland from prunes imported primarily from Portugal the manufacturer conducted a brisk trade not only with whisky distilleries in the UK but also those worldwide, consequently Prune Wine was an important constituent of early malt whisky.

The Whisky Trade Review commented on the state of the industry: “Distillers and Blenders of Whisky- Irish, Scotch, English or Welsh, for each country is now making whisky – use their best endeavors to supply the trade with an article which is palatable or which will be palatable after a little time. But it should be remembered that both the distiller and the blender uses his own idea almost entirely as to what he considers a palatable flavour. The public, whilst approving of nearly every honest whisky-by honest we mean whisky made of sound and wholesome cereals-invariably say that it lacks something; it wants a finish. No one has a right to shudder or pull a wry face after taking a glass if whisky; yet how often is this so, perhaps nine cases out of ten, yes, and this is in London, Dublin and Edinburgh.”

The Wine and Spirit Trade Record, in referring to the foregoing, says, in its issue of May, 1900; “How to meet this want-to supply this lack of finish-was obviously a matter of first importance to the Whisky Trade. This lead to numerous articles being, from time to time, offered on the market. Among these, Patent Prune Wine has obtained a position so exceptionally high, that there can be no hesitation in saying that it has successfully supplied the need. Those closely connected with home trade are aware that Prune Wine-having stood the severest of all tests, the tests of time-at present commands an enormous sale, whilst the Customs statistics of it exportation abroad furnish incontestable evidence that its merit is fully recognised in almost all foreign markets of importance.”

In the 1870’s WM. & P. Thompson, Ltd of Dublin, Ireland manufactured ‘prune wine’ in what can only be described as a grand fashion, “The factory in Dublin is situated in Mabbot Lane, and compromises as extensive range of buildings, beneath which are spacious wine vaults. Steam power is employed in the manufacturing process, and the mills for grinding the prunes, the fermenting apparatus, the huge vats and other appliances, are all on a scale of magnitude commensurate with extensive business operations of the Firm.  Adjoining the Factory is a large Bonded Warehouse built by the Firm expressly for the storage of their own wines. Here Prune Wine remains until fully matured, previous to shipment to all parts of Europe, the United States, Canada, the West Indies, South America, etc..”

Prune Wine, the manufacturers claimed, was used ‘upon young spirits, which have often to put into early consumption to meet the requirements of price, is to neutralize their acrid, fiery, and impure properties, as well as to give the appearance and the qualities of Age-for this purpose it is universally used.’  Prune Wine, they continued to claim, is also extensively used for old Spirit, with the admitted effect of imparting Body, and a character and Finish which cannot be acquired by any other known means. The use of Prune Wine not only effects a great saving, but invariably leads to an increase of business, as Spirit operated upon by it at once attracts the palate of consumers. Storing for years on Sherry Casks will not give that delicious aroma and roundness on the palate which Patent Prune Wine imparts in a few hours. 

Endorsements of Thompson’s Prune Wine by Experts

WM. & P. Thompson, Ltd were quick to make much of endorsements from the scientific community to prove the ‘wholesomeness’ of their Prune Wine. The “Scientific Times” New York, in its issue of Feb 24th, 1883 states: “When added to spirits in proper proportions Patent Prune Wine effectually eliminates Fusel Oil, the presence of which is so objectionable and injurious to health, and imparts a delicious flavour and character.”

Sir Charles Cameron (3) wrote: “The flavour of recently distilled whisky is extremely acrid, owing chiefly to the presence of Fusel Oil; on adding, however, a small quantity of Prune Wine, and allowing the mixture to stand for a day or two, the new Whisky acquires a most agreeable flavour.”  Sir Charles goes on to state that “Unlike flavouring essences, this Wine is perfectly Wholesome per se; and I have no doubt but that its fragrance and pleasant flavour will induce many to make it their beverage, unmixed with other fluids.”

Granville H. Sharpe, F.C.S (4)., wrote: “I find that, when added to a coarse Spirit containing an undue amount of Fusel Oil, and in the proportion recommended by the manufacturers, the objectionable flavour is at once removed, and a liquor of agreeable aroma and bouquet remains.”

Dr. William Wallace (Public Analyst for the City of Glasgow) wrote: “I have made a careful examination of the Prune Wine manufactured by Messrs. Wm & P. Thompson, Dublin and have tested mixtures of with various brands of Scotch Grain Whisky. The liquor is itself very agreeable, and when added to silent or grain spirit it communicates to it a pleasant flavour and odour resembling very closely the taste and bouquet resulting from age. I consider it perfectly wholesome, and see no reason to doubt that it will be largely used in Scotland, as it has been for many in Ireland, as an improver of Grain Whiskey.”

The National Guardian, Glasgow, November 16th, 1900 wrote: “Many attempts have been made to provide a specific capable of making whisky palatable, without interfering with its quality. The best, so far as we have seen, is Thompson’s Patent Prune Wine, which has obtained a high reputation. It is a genuine fermented wine, quite limpid, and of a flavour very pleasant, while not too pronounced. It has a great deal of body, and. On unmatured spirit, has a softening and improving effect which is very remarkable.”

Interestingly the Editor of the Licensed Victuallers’ Guardian wrote that “The article known as Thompson’s Prune Wine has been before the Trade a great number of years, and the steady and large increase of consumption is tangible evidence of its value. At present there is scarcely a part of the world in which it is not largely used and fully appreciated. The new law with regard to adulteration will still further increase the sale of Prune Wine, as worthless and spurious compounds, sold under various names, will be no longer saleable. We have ourselves examined this wine, and must pronounce it an elegant article.”

As further proof of the value of their product, Wm. & P. Thompson quoted from the ‘Scientific Times’ in New York, 24th February, 1883: “Patent Prune Wine was first invented by Mr. Wm. Thompson, of Dublin, head of the firm of W&P Thompson, of that city. From that day to this it is the only article fermented from the Prune, and the above firm is the only one in the world having the right to manufacture and sell it. After a careful examination and scrutiny of its merits, it proved so useful and valuable an adjunct to the trade that the patent rights were granted in England, (this would have included Ireland) and after the expiration of the time a further renewal was granted, which is irrefutable proof that it possessed all the merit at first claimed for it. Patent rights have also been secured for the United States, Germany, and France, and the name is protected in all these countries by Trade Mark.”

Further Proof of Quality from Warrenheip Distillery, Australia

William Strachan, Secretary of the Warrenheip Distillery in Australia, wrote to Wm. & P. Thompson in a letter dated Melbourne, 21st November, 1866 that he had experimented with Prune Wine on two samples of Warrenheip whisky, ‘with very satisfactory results’. The first sample fresh from the still and he remarked that “the improvement was very marked; the acrid, fiery taste entirely disappeared, the flavour became mellow and pleasant, and I should have no difficulty in placing spirits so treated at once on the market.  In the other instance the whisky had been about three years in bond, and although the alteration was not so decided, the spirit was considerably improved. I intend bringing this subject under the notice of the Directors, as the advantage of converting raw Spirits into a merchantable commodity is obvious enough.”

Further evidence of the success of the Warrenheip Distillery in eyes of the public was available in the trade papers of the day. An extract from the “The Wine Trade Review” from January 15th, 1868 is evidence of how much the Warrenheip Whisky was enhanced in the public estimation between the years 1866 and 1868;

“At the Ballarat Agricultural and Pastoral Society’s Show, the
following prizes were awarded for Whisky manufactured in the Colony:
12 Bottles Whisky, made in the Colony.
1st Prize-Warrenheip Distillery Co.”

Not unsurprisingly, the Australian agents for WM. & P. Thompson, Ltd also endorsed Prune Wine as follows; “We wrote to you on the 27th ultimo, as per duplicate enclosed. Since then the Chief Inspector of Distilleries (Now, that would be an acceptable form of employment!) has tried some of your Prune Wine with spirits recently distilled, and he reports that it takes away the raw flavour, and imparts to the mixture a mellowness which only Old Spirits possess. With such a satisfactorily trial we think you ought to send out a shipment, as recommended in our last. We are, dear Sirs, yours truly, Lorimer, Marwood & Rome.”

Fining of Whisky

Further, Prune Wine was used by distillers, blenders and spirit merchants for Fining(5) after the spirit had been reduced (with water) ‘it will make its way through the whole body of the blend, and fine it, carrying down all impurities, and will leave the spirit brilliant, and finished for almost immediate use.’ When much Fusel Oil was present the addition of Prune Wine in some cases could cause the spirit to become cloudy and if hard water, which contained lime and was not boiled, was used in reducing the spirit then the addition of Prune Wine could make the spirit appear to have a bluish discoloration. In this case WM. & P Thompson recommended ‘to get some Spanish Earth at a Druggist’s, make it into a past with hot water, then into a liquid with a gallon or two of the Spirit; throw all into the cask, rousing well wit a stick or brush. About one pound of Spanish Earth per 100 gallons of whisky is the quantity to be used.’

The End of an Era

It is always seductive to apply the standards of today to the past and the past generally looses. However one should keep in mind that whisky or whiskey was not the product that we are familiar with and the addition of flavorings and other adulterations was common practice all in an attempt to avoid the costly practice of lengthy & expensive maturation in wood. 

Wm. & P. Thompson must have been horrified at the introduction of the Immature Spirits Act (1915) and the resulting destruction of their business in the home market. Internet searches reveal some interesting historical notes on Wm. & P. Thompson; the records of the Irish Dail show a debate the subject being the 1930 Treaty of Commerce and Navigation with Portugal. More interestingly is the discussion of the importation of prunes in March, 1944 and opposition claims that the Company was receiving special treatment due to the fact that the Secretary of the Minister of Supplies had a controlling interest in the Company.  

Incidentally the three year rule for Scotch whisky maturation was introduced by the Immature Spirits Act (1915) and amusingly, two monkeys helped solve the problem. The first monkey was forced to drink new whisky and ‘became quarrelsome no doubt due to the fusel oil (which was well known for making men fighting drunk)’ and the other became acquainted with ‘fine old whisky’ and it soon became ‘markedly hilarious’. Once both beasts had returned to sobriety the experiment was reversed causing the ‘quarrelsome beast to cheer up somewhat and the contented one to become aggressive’. The general conclusion was the new spirit (containing fusel oil) did have an adverse effect, ‘at least on monkeys’. The type of monkeys has not been recorded but the odds are they were chimps, the Volkswagen Beetle of the primate world. Greenlees Brothers, taking advantage of the publicity, later introduced to the market place a blend called ‘The Monkey Special’ and is of no relation to the contemporary Monkey Shoulder I suspect. 

Today Wm. & P. Thompson exists as Thompson’s Prune Wine Export Limited with an address in Nangor Road in Dublin. There is no indication, other than their name, of what business they conduct.

Lawrence Graham

1 – Blavag Books, Glasgow, ISBN 0951202022
2 – A most objectionable contamination of whiskey is the grain oil or fusel oil (amylic alcohol), which is generated during fermentation of the mash. Its boiling point being much above that of water and of ethyl alcohol, the greater part of it remains behind if the distillation be carefully conducted. Still, traces of fusel oil are generally present in whiskey. Amylic alcohol is the substance which imparts to raw spirit its disagreeable odor. By Harvey Wickes Felter, M.D., and John Uri Lloyd, Phr. M., Ph. D., 1898.
3 – The managing director of the Weekly Mail is a son of John Cameron, newspaper proprietor, of Glasgow and Dublin, and was born in the latter city in 1841. He was educated at Madras College, St. Andrews, and Trinity College, Dublin, where he was First Senior Moderator and Gold Medallist in 1862. In the same year he graduated M.B. and C.M., being First Place-man in both instances, and he continued his medical education at the great schools of Paris, Berlin, and Vienna. In 1864, however, he settled to newspaper work, in the editorial chair of the North British Daily Mail. This he continued till 1874, when he was elected M.P. for Glasgow. He represented the city from 1874 to 1885, the College Division from 1885 to 1895, and Bridgeton Division from 1897 to 1900. In the House of Commons he was an active member. Among many other labours, he carried through the resolution which led to the adoption of sixpenny telegrams; he brought in and secured the passing of the Inebriates Acts, as well as the Acts abolishing imprisonment for debt in Scotland, and those conferring the municipal franchise on women. He also secured various reforms in the Scottish Liquor Laws. He was Chairman of the Departmental Committee on Transit of Cattle Coastwise in 1893, and of the Departmental Committee on Habitual Offenders (Scotland), 1894, and he was a member of the Royal Commission on the Liquor Licensing Laws in 1895. At the same time he has been the author of a number of notable pamphlets on medical, social, and political subjects. In 1893 his long journalistic and parliamentary services were recognised with the honour of a baronetcy. Sir Charles has been twice married: first in 1869 to Frances Caroline, daughter of William Macaulay, M.D., who died in 1899, and secondly to Blanche, daughter of the late Arthur Perman. He resides at Glenridge, Virginia Water, and finds active recreation in motoring, riding, and travel. From Who’s Who in Glasgow in 1909.
4 – Granville H. Sharpe, F.C.S. was an Analytical and Consulting Chemist, was the former Principal of the Liverpool College of Chemistry (before 1892), scientific author and respected lecturer.
5 – Fining called collage in French, from the verb coller, to fine. This important cellar operation causes all sediment to fall to the bottom of the cask leaving the spirit bright and WM. & P. Thompson recommend the use of Spanish Earth (A substance obtained from the soil originally found in Spain. It is a complex silicate with the unique property of absorbing colloidal matter, both positive and negative and is extensively used in fining. The main sources of Spanish Earth today are the USA and parts of South America.)