128 



SCIENCE. 



[Vol. XVI. No. 396 



employed in breweries in Denmark, Germany, and elsewhere 

 in Europe, and there is no scientific reason why the same 

 system should not be carried on in this country to the great 

 improvement of our heers and wines. 



At the old Carlsberg brewery near Copenhagen, Professor 

 Hansen has cultivated two varieties of bottom S. cerevisice, 

 which give different results in practice. One gives a beer 

 well adapted for bottling, and is chiefly employed for home 

 use. The other gives a good draught beer, containing rnore 

 carbonic acid than the former variety; it is not adapted for 

 bottling, but is much preferred by German brewers, and is 

 therefore chiefly cultivated for export. 



Experiments upon an industrial scale are being carried on 

 at Burton-on-Trent, in England, with different species of 

 pure yeast. Several varieties of S. cerevisim have been sep- 

 arated from the yeast generally employed and cultivated, 

 which, when used on a practical scale, give entirely different 

 results, both as to flavor, brightening, attenuation, and 

 mode of separation of the yeast. Experiments have also 

 shown that these characteristics can be maintained unim- 

 paired throughout a very great many successive fermenta- 

 tions in the brewery. Cultivations have been started from 

 a single yeast cell, and with proper care have been main- 

 tained for a long time. 



On a commercial scale the cultivation should be conducted 

 in sufficiently large vessels to yield the necessary amount of 

 yeast used for fermentation. For this purpose two vessels 

 should be employed, one in which the wort or other sugar 

 solution used for cultivation is sterilized by being boiled, 

 then stirred and aerated, excess of pressure being prevented 

 bymeans of air filtered through sterilized cotton; intotheother 

 (the fermenting vessel, previously sterilized bysteam) the ster- 

 ilized wort or sugar solution is forced, and pure yeast from the 

 laboratory added. When the fermentation is at an end, the 

 liquid is run off, the apparatus filled with wort or sugar solu- 

 tion, stirred, and very nearly emptied. The wort so obtained, 

 and containing yeast, is then transferred to the brewing 

 vessels; the residue in the apparatus, with the addition of 

 sterilized wort, serves for the future production of yeast. 

 Pure yeast can thus be continually obtained without fresh 

 inoculation, as the small amount remaining in the ferment- 

 ing vessel serves this purpose. These vessels are jacketed 

 and provided with the necessary safety-valves, ventilators for 

 admitting filtered air, exit tub^s for the escape of steam and 

 carbonic acid, thermometers and manometers for regulating 

 temperature and pressure, and inlets and outlets for wort, 

 beer, and yeast. 



Distillation. — The object of the distiller is to separate 

 the alcohol contained in the fermented wort from the foreign 

 matter with which it is associated. For this purpose he has 

 resort to a still. The alcohol thus produced is not, as has 

 been well known for some time, a single substance, homo- 

 geneous, always the same in its nature, form, and effects; 

 on the contrary, it is an extremely variable body, of diverse 

 chemical composition and physical characteristics; it is not 

 one alcohol, but many, which chemists have divided into 

 several series. 



The distiller commonly divides the pi'oductof his still into 

 three classes: (1) products with a bad taste, the heads; (2) 

 alcohol, properly speaking; and (3) products with a bad 

 taste, the tails. The first and third are kept separate from 



the middle, which is the most valuable portion. Table 

 I., according to Dr. Eabuteau, gives the boiling points of 

 these different products. 



Table I. — Showing the Boiling Point of Different 

 Products. 



Products of Distillation. 



Products with a bad taste, the heads: — 



Aldehyde.. 



Acetic ether 



Alcohol, grain spirits, ethyl alcohol 



Products with a bad taste, the tails: — 



Propyl alcohol 



Butyl alcohol 



Amyl alcohol 



Valerianic ether 



Amyl acetate and other nameless productj 



Aldehyde is a colorless, easily mobile liquid, having a 

 specific gravity of 0.8009 at 0° C. (Eopp). Its vapor density 

 was found by Liebig to be 1.532, who also states, that, when 

 inhaled in large quantities, the vapors, of a peculiar ethereal 

 suffocating odor, produce a cramp, which for a few seconds 

 takes away the power of respiration. (Isidore Pierre com- 

 pares its action to that of sulphurous acid. ) It is miscible 

 with water in all proportions, heat being evolved, and it 

 is likewise soluble in both alcohol and ether. The addition 

 of water raises the boiling point of aldehyde. It absorbs 

 oxygen, and is slowly converted into acetic acid.' 



Ethyl acetate or acetic ether is a mobile liquid possessing 

 a penetrating, refreshing smell and a pleasant burning taste. 

 It has a specific gravity of 0.91046 at 0° C. (Kopp).' Its va- 

 por density was found by BouUay and Dumas to be 3.016. 

 It mixes with alcohol, ether, acetic acid, etc., in all propor- 

 tions, and dissolves a large number of resins, oils, and other 

 organic bodies. Its action in many cases, when used as medi- 

 cine, resembles that of common ether, but it possesses a more 

 agreeable taste and smell. It is also used for addition to the 

 poorer classes of wine, liquors, etc.' According to Professor 

 Dujardin-Beaumetz, the toxic dose of aldehyde is from 1 to 

 1.25 grams, and that of acetic ether 4 grams, per kilogram of 

 the weight of the animal. 



Methyl alcohol is the lowest form of the alcohol series, 

 and when pure is a colorless, mobile liquid, having a vinous 

 smell closely resembling that of ethyl alcohol. It has a 

 specific gravity of 0.8142 at 0° C. (32° F.) (Kopp). The 

 boiling point, as stated by various observers, varies from 

 58.6° to 66.5° C. (137" to 152" F.), owing to the great diffi- 

 culty of obtaining it in a perfectly anhydrous condition. 

 The difference between the densities of mixtures of methyl 

 alcohol and ethyl alcohol with the same proportions of 

 water is so small that the tables ordinarily used for the latter 

 may be employed for most purposes in ascertaining the 

 strength of the former. 



Methyl alcohol is miscible in all proportions with water, 

 ethyl alcohol, and ether. In its solvent and chemical prop- 

 erties it closely resembles ethyl alcohol. 



* Roscoe and Schorlemmer^s Chemistry. 



