PEESERVATION AND STOEAGE. 



271 



side. The movable lids are fitted with an air-tight packing 

 ring. 



Hop presses are supphed by many engineering firms at 

 prices ranging from about £45 to £300, according to size 

 and strength ; and the drums cost about £2 to £3 apiece. 

 Other forms of drums made of wood or prepared millboard, 

 and collapsible drums, are often recommended, but are not 

 very widely used, being of insufficient strength, though their 

 lightness and cheapness are favourable points. The usual 

 size of hop drums is about 50 by 24 inches, to- hold 8 cwt. 



Fig. 77. 

 Drum for light pressing, with 

 movable bottom and lid. 



Fig. 78. 

 Drum with movable bottom and 

 lid, and lateral flanged joint for 

 opening. 



According to Thausing the cost of packing amounts to 

 about 4s. lOd. per cwt. in canvas pockets, 6s. in drums and 

 9s. 6d. in metal-lined cases, the latter being only suitable 

 for use once. 



Hops that have been sulphured, pressed and well packed 

 will keep for two years and more, in good condition, fit for 

 use, as has been proved by many instances in practice. 



That careful drying and cool storage out of contact with 

 air preserve hops is beyond all doubt, and there only remains 

 the question what part is played in this connection by sul- 

 phurous acid. Before going into this matter it may be 

 remarked that the small quantity of this acid introduced 



