SPIRITS. In the chemical sense the word is sometimes applied to acids having a volatile character, as "spirits of salts" or hydro chloric acid. The name is generally restricted to distilled liquors. The Spiritus Rectificatus of the British Pharmacopoeia is a mix ture of ethyl alcohol and water in the volume proportions of 90 to 1o. There are also four standard diluted alcohols recognized by the same authority containing respectively 7o, 6o, 45 and 20% of ethyl alcohol by volume. The spirits of the British Pharmacopoeia (e.g., Sp. aetheris nitrosi; sp. chloroformi; sp. camphorae) are solutions of various substances obtained either by distilling them with, or dissolving them in, rectified spirit.
According to the British Spirits Act of 188o "spirits" means spirits of any description and includes all liquors mixed with spirits, and all mixtures, compounds, or preparations made with spirits. The same enactment defines "plain spirits" as "British spirits (except low wines and feints) which have not had any flavour communicated thereto or ingredient or material mixed therewith," and "spirits of wine" as "rectified spirits of the strength of not less than 43 degrees above proof," i.e., 75.36% of alcohol by weight or 81.59% by volume.
In its popular use "spirits" is generally understood to mean alcoholic beverages, e.g., brandy, rum, whisky, distilled from liquids which have undergone a process of fermentation.
While "spirit" has never been a popular term in the United States it does have the same connotation as in Great Britain. But the Federal Government has defined "spirit" to mean an alcoholic distillate of over 190 degrees proof. Alcoholic distillates of lesser proof are termed whisky with qualifying adjectives which identify the proof and type of whisky.
Thus a strong spirit 1 oo volumes of which would, on the addition of water, give 166 volumes of proof spirit, is described as having a strength of 166% proof, or 66 degrees over proof, whilst one which contains, in too volumes, sufficient alcohol to give 45 volumes of proof spirit has a strength of 45% proof, or 55 degrees under proof. The proof gallon equivalent of a mixture, the strength and volume of which have been determined, can be ascertained by multiplying the volume in gallons by the strength and dividing by 1 oo. Absolute alcohol has a strength of 75.35 degrees over proof.
This method of assessment of alcoholic strength depends upon the difference in the respective specific gravities of alcohol and water, and the determination of the specific gravities appropriate to mixtures of these two sub stances is therefore of great im portance.
At the request of the Brit ish Government the Royal So ciety undertook an investigation of this problem towards the close of the i8th 'century.
The work was entrusted to Sir Charles Blagden, the secretary, and George Gilpin, the clerk to the Royal Society.
Results of their experiments were published in the Philo sophical Transactions 179o-94 and were of such great merit that they are incorporated in many of the official tables of the present day, including those legalized in Britain in 1915. Tralles in 1911 conducted a similar investigation for the Prussian Government, whilst Gay Lussac (Paris, 1824), McCulloch (Washington, 1848), Baumhauer (Amsterdam, 186o), Mendeleeff (St. Petersburg, 1865), the Kaiserliche Normal Eichungs Kommission (Berlin, 1889), and Bureau of Standards (Washington, 1913 and 1929) were also responsible for considerable work under the auspices of their respective Governments. In the United States a "proof" standard is adopted; Section 3249 of the Revised Statutes pro vides that "proof spirit shall be held to be that alcoholic liquor which contains one-half its volume of alcohol of a specific gravity of 0.7939 at sixty degrees Fahrenheit." In Holland also a "proof" spirit forms the basis of the revenue charge, the standard being 5o% by volume of anhydrous alcohol at 15° C.