PREPARATION OF ALCOHOLIC DRINKS. 475 



and succinic acid (0'6-0'7 per cent.). Yeast is either added intentionally or it 

 reaches the mixture from the air, which always contains its spores. When yeast 

 is completely excluded, or if it be killed by boiling, [or if its action be prevented 

 by the presence of some germicide], the fermentation does not occur. The 

 alcoholic fermentation is due to the vital activity of a low organism (Schwann, 

 Mitscherlich, Pasteur). 



In the preparation of brandy, the starch of the grain or potatoes is first 

 changed into sugar by the action of , diastase or maltin. Yeast is added, and fer- 

 mentation thereby produced ; the mixture is distilled at 78'3C. The fusel oil is 

 prevented from mixing with the alcohol by passing the vapour through heated 

 charcoal. The distillate contains 50-55 per cent, of alcohol. 



In the preparation of wine, the saccharine juice of the grape the must after 

 being expressed from the grapes is exposed to the air at 10-15C., and the yeast 

 cells, which are floating about, drop into it and excite fermentation, which lasts 

 10-14 days, when the yeast sinks to the bottom. The clear wine is drawn off 

 into casks, where it becomes turbid by undergoing an after-fermentation, until the 

 sugar is converted into alcohol and COo, which is accompanied by the deposition 

 of some yeast and tartar. If all the sugar is not decomposed which occurs when 

 there is not sufficient nitrogenous matter present to nourish the yeast a sweet 

 wine is obtained. Wine contains 89-90 per cent, water, 7-8 per cent, alcohol, 

 together with sethylic, propylic, and butylic alcohol. The red colour of some 

 wines is due to the colouring matter of the skin of the grapes, but if the skins be 

 removed before fermeutation, red grapes yield white wine. 



When wine is stored it develops a fine flavour or bouquet. The characteristic 

 vinous odour is due to (Knantldc ether. The salts of wine closely resemble the salts 

 of the blood. 



In the preparation of beer the grain is moisten, and allowed to germinate 

 when the temperature rises, and the starch (68 per cent, in barley) is changed 

 into sugar. Thus "malt" is formed, which is dried, and afterwards pulverised, 

 and extracted with water at 70-75, the watery extract being the "wort." 

 Hops are added to the wort, and the whole is evaporated, when the proteids are 

 coagulated. Hops give beer its bitter taste, make it keep, while their tannic acid 

 precipitates any starch that may be present, and clarifies the wort. After being 

 boiled, it is cooled rapidly (12C.); yeast is added, and fermentation goes on 

 rapidly and with considerable effervescence at 10-14. Beer contains 75-95 per 

 cent, water; alcohol, 2-5 percent, (porter and ale, to 8 per cent.); C0 2 , 0'1-0'8 

 per cent.; sugar, 2-8 per cent.; gum, dextrin, 2-10 per cent.; the hops yield 

 traces of protein, fat, lactic acid, ammonia compounds, the salts of the grain and 

 of the hops. 



In the ash, there is a great preponderance of phosphoric acid and potash, both 

 of which are of great importance for the formation of blood. In 100 parts of ash 

 there are 40 '8 potash, 20 '0 phosphorus, magnesium phosphate 20, calcium 

 phosphate 2 - 6, salica 16'6 per cent. The formation of blood, muscle, and other 

 tissues from the consumption of beer is due to the phosphoric acid and potash, 

 while if too much be taken, the potash produces fatigue. 



Condiments are taken with food, partly on account of their taste, and 

 partly because they excite secretion. Common salt, in a certain sense, 

 is a condiment. We may also include many substances of unknown 

 constitution which act upon the gustatory organs, e.g., substances in 

 the crust of bread and in meat which has been roasted. 



