PRESSING THE POMAGE. 57 



tne temperature is favourable, ranging from 60° to 70°, very evident 

 signs of increased action will soon appear. The bubbles of 

 Carbonic Acid Gas begin to rise so quickly that a constant hissing 

 noise is heard. These bubbles carry up with them to the surface 

 many of the lighter particles of the cellular tissues of the fruit that 

 have passed through the press with the juice, and thus a thick scum 

 is formed on the surface, to which the cells of the yeast plants are 

 gradually added in considerable quantity. This scum soon becomes 

 a thick spongy crust, sometimes called the " upper lees," and it is 

 supported on the surface by the Carbonic Acid Gas arising beneath 

 it, so long as this gas is generated in sufficient quantity. At tl:c 

 same time that this action is going on, the more solid particles of 

 tissue that have escaped through the press, sink into the fluid, 

 accompanied with a considerable portion of the mucilage, and an 

 abundance of yeast cells. This deposit forms the "lees." or "lower 

 lees," at the bottom of the barrel. 



As the Fermentation declines the hissing noise moderates, 

 since less Carbonic Acid Gas is generated ; the floating crust gets 

 dry on the surface, cracks, and losing its buoyancy, falls in 

 fragments to increase the amount of the lees below. By this time 

 the liquor will have become moderately clear, or will have 

 " dropped bright " as the phrase goes. It should then be racked 

 off and the temperature kept low. This is the crucial point of the 

 whole process, and requires close observation and care ; for any 

 delay at this stage incurs the risk of injurious secondary fermen- 

 tation. 



The clear liquor should then be racked, or run off from the 

 lees into a fresh cask, perfectly clean and sweet, by means of a 

 syphon, so as to prevent any unnecessary exposure to the air. A 

 considerable " ullage " should be left in the barrel, and the bung 

 is usually left open for some days. It is better to close the cask with 

 a bung through which a glass tube passes, one end being open into 

 the " ullage " space, and the other outside end bent down and up 

 again, so as to hold a tablespoonful or two of water in the lower 

 bend ; or the outer end of the tube may be simply bent down into 

 a shallow cup of water. The advantages of this bent glass tube are, 

 that if an excess of gas is formed in the barrel, its pressure would 



