336 



small disc of tin, known as a stud, is then soldered over the hole, 

 with a small vent-hole left open. The tins are then treated like 

 canned fruit, and placed in a hot water bath until the temperature 

 right through the mass reaches over 180 F. (82 C.), so as to 

 make sure that all germs are destroyed. This done, a drop of 

 solder closes the vent-hole. If the operation has been successfully 

 done there is no air^ inside, and on cooling a vacuum is created, 

 which causes a contraction, shown by a compression of the sides 

 and ends. If, on the other hand, the mass has not been thoroughly 

 sterilised; or if germs have got access to it before soldering the 

 cover, fermentations will before long set in, which will be accom- 

 panied by evolutions of gases inside, and the ends as well as the 

 sides of the tin will bulge out. 



Should this happen, the "blown" tins are placed once again 

 into the hot water bath, and the temperature of the whole mass 

 raised once more to 180 F. 



Freshly-filled tins should be kept under observation for a 

 fortnight or so before being encased, and as a further precaution 

 the tins are often tested. 



This is done by immersing them for a few minutes into hot 

 water. The air inside thus expands, and should the least hole 

 exist its presence will be revealed by a stream of small air bubbles. 



It is thus seen that fruit pulp affords a simple and ready 

 means of storing until needed, all the out-of- season fruit we 

 require for jam-making, marketing the balance at a time 

 when the market is not glutted with the particular fruit thus 

 preserved. 



One ton of apricots makes one ton of pulp, the water added 

 making up the weight of the pits removed. 



For converting into jam, about fib. of sugar is added to 

 every pound of the pulp and the mass boiled for about 30 minutes. 



JELLIES. 



Fruit jellies constitute one of the most attractive and tasty 

 forms of utilising fruit ; they keep indefinitely. Apples, quinces, 

 plums, apricots, grapes, strawberries, guavas, Cape gooseberries and 

 a host of other fruit can thus be treated. 



Pectic acid, su^ar and heat combined with fruit juice, cause the 

 mass to set in a jelly. For that reason fruits not quite over-ripe 

 are preferable, as they contain a larger amount of pectic acid, which, 

 on ripening, is gradually converted into pectin, whilst the fruit 

 becomes soft to the touch. When combined with sugar, and boiled 

 for a certain time and then cooled, fruit juices coagulate and set 

 into a jelly. 



The amount of sugar required is approximately equal to that 

 of the fruit juice. In order to impart to the jelly a clearer fracture 

 lemon juice is at times added. 



