JOIIANN CARL LEUCIIS ON WINE-MAiaNG. 195 



the acetous fermentation. The liquid begins to effervesce, flocu- 

 lent particles swim about in it, heat is generated, oxygen is at- 

 tracted from the atmosphere, and the fluid is changed into vin- 

 egar. 



11. 



IMPLEMENTS USED IN WINE-MAKING. 



The principal implements used in the manufacture of wine 

 are the Thermometer and the Areometer. The former is used to 

 measure the temperature during fermentation ; the latter to meas- 

 ure the saccharine matter of the must and the alcohol of the wine. 

 Besides these, there are other implements used to ascertain the 

 acids and the quantity of carbonic acid forming. 



The Thermometer. 



The thermometer is used to measure the variations of tempera- 

 ture. The principle upon which it is constructed is that matter 

 expands, or increases its volume, when heated, and contracts when 

 cooled. Thus a given quantity of mercury occupies more space 

 when warm than when cold. For many reasons, it is found con- 

 venient to use mercury for the construction of thermometers for 

 common purposes ; though for scientific jDurposes, where extreme 

 accuracy is required, other substances are employed. The mer- 

 curial thermometer, however, is sufficiently accurate for the pur- 

 pose for which it is required in wine-making. There are three 

 kinds of mercurial thermometers used in different parts of the 

 civilized world. The principle of all is the same. They consist 

 of a bulb containing mercury, to which is attached a glass tube 

 with a very small bore. As the mercury in the bulb expands by 

 heat, it rises in the tube, the height to which it reaches at various 

 temperatures being marked on a scale attached to the tube. The 

 only difference between the thermometers in use is the number 

 of degrees by which this expansion is marked on the scale. 



In Keaumur's thermometer the point at which water begins to 

 freeze is marked ; that at which it boils is marked 80 ; and the 

 intervening space is divided into 80 equal degrees, marked from 

 to 80. 



In Celsius's thermometer the freezing point is marked 0, the 

 boiling point 100 ; the intervening space being divided into 100 

 degrees, marked from to 100. 



In Fahrenheit's thermometer, (or zero) indicates a tempera- 

 ture much below the freezing point of water, which is marked 32, 

 while the boiling point is marked 212. The space between the 

 freezing and boiling points is therefore divided into (212—32) 

 180 parts. 



