No. 2 (1921) REMARKS ON CANNmO II9 



by a second operative as soon as opened, so that the can is now 

 practically exhausted of air. 



The exhausted cans are now finally processed at 15 lb. pressure, 

 i.e., 250 F., the process continuing for about i hour in the case of 

 I lb. cans. The cans are subsequently tested either by striking 

 them with a piece of iron like a spike nail, or by striking them 

 against an anvil ; the sound given by a perfect can and that of one 

 with the slightest perforation are readily distinguishable by a 

 trained ear. In Japan the completed tins were kept for a week or 

 two in a warm store, by which time any imperfect can discloses 

 itself. This concludes all essential operations and it will be 

 noticed that nothing but wholesome fresh fish has been placed in 

 the cans, and that preservation is effected by sterilization and 

 hermetical closure. It remains merely to clean, varnish, and 

 decorate the cans with some suitable and attractive label. 



183. Prawns. (Called 'shrimp' in the United States of 

 America). — These are easy to can but not so easy to preserve in good 

 condition when canned, as may be judged from the fact that the first 

 American canner of prawns began experiments in 1867 but did not 

 meet with success till 1875, an excellent commentary on canning 

 difficulties and on the arm-chair criticisms of canning experiments 

 and results ; compare the similar experience in the canning of 

 sardines in the United States of America when first introduced 

 by their canners 



184. The method adopted in the Government Cannery (where 

 prawns were first canned in India, since they were never previously 

 canned at Mahe) is as follows, and is based on the method of semi- 

 drying prawns at Tanur. 



The fish must of course be fresh and if possible alive when 

 brought to the cannery; though Indian — non-European — taste 

 seems ordinarily to prefer the ' white ' variety they do not can so 

 well as the ' red ' ones, being less tasty, besides presenting a 

 pallid, ugly appearance in the tins as contrasted with the bril- 

 liance of red prawns. They are at once dipped for a minute or so 

 in boiling wa.ier, the precaution being taken of dipping only small 

 quantities of prawns at a time ; for instance, a large iron boiler 

 about 48 inches long, 20 inches wide, and 14 inches deep, is set 

 over a furnace burning wood and provided with a small chimney ; 

 into this are poured about 40 gallons of water which are brought 

 by a sharp fire to the full boiling point ; when boiling, two wire 



