THE ATMOSPHERE. 9 



sugar is formed by the oxigen of the air combining with 

 the substance of. the apple. 



During this change, no spirit or alcohol is formed, and 

 the liquid is of course useless to the distiller, and can do 

 no injury by spreading intemperance. But if it be expos- 

 ed to the air until a second portion of oxigen is added, 

 the sugar is destroyed and alcohol formed. 



Alcohol, or spirits, whenever it exists, whether in beer, 

 cider, wine, gin, brandy, rum, or any other intoxicating 

 liquor, is formed from sugar. 



In the second change, or stage of fermentation, then, 

 sugar is destroyed and alcohol formed. This change is 

 frequently rapid and violent, especially if the liquor be 

 moderately warm, and freely exposed to the atmosphere. 

 When a cask of cider, recently from the press, is placed 

 in a warm situation, and more if it be shaken, so as to 

 bring a great number of particles in contact with the air, 

 a commotion, sometimes violent, arises in the liquid, 

 which is produced wholly by the action of oxigen upon 

 it. If casks be filled with the juice of the apple as soon 

 as it is expressed, and immersed wholly under water, or 

 placed in any other situation so as entirely to exclude the 

 air, the second change will be prevented, and no alcohol 

 formed. 



A third portion of oxigen destroys the alcohol, and 

 forms an acid. This change is always more gradual than 

 the second, and sometimes produced with difficulty ; 

 though it partially takes place, whenever cider, beer, or 

 wine, is exposed for any length of time to a warm atmo- 

 sphere. The change may be wholly produced in the 

 liquids just named, or in alcohol, in almost any other 

 form, if a large surface be exposed to the air, frequent 

 motion given, and yeast or some other fermenter added. 



Not only common vinegar, but most of the stronger 

 acids, are formed by the agency of oxigen. It has al- 

 ready been observed, that it constitutes about three fourths 

 of nitric acid. Sulphuric acid, or oil of vitriol, is formed 

 by burning sulphur in oxigen, or with saltpetre, which 

 contains it in large quantities. Phosphoric acid is formed 

 by burning phosphorus in a similar way. 



For a long time it was supposed, that all acids were 



