EvaroratED M1i.K—SEALING 135 
oblong trough, filled with hot water and through which the cans 
pass on an endless chain. In the case of leaky cans, the heat of 
the hot water bath expands the air in the cans and causes it to 
escape throuch the leak in the seal and percolate upward in the 
water. in the form of air bubbles. The operator standing over 
the test trough picks the cans which expel air bubbles out so 
that the defective seals can be mended. 
Most condenseries manulacturing evaporated milk are now 
using a hot water 
bath for testing the 
sealed cans. But ex- 
perience has shown 
that the hot water 
baths built on the 
continuous chain 
principle often — fail 
to give the desired 
efficiency. This is not 
the fault of the ma- 
chine, but it is due 
to the fact that it 
becomes very tiresome for the inspector to wateh the moving 
Fig. 57. Chapman automatic can tester 
Courtesy of Schaefer Mfg. Co. 
line of cans in the water bath and he soon becomes careless and 
his work inefficient. It has been found that baths constructec 
and operated on the principle of submerging a whole tray full 
of cans, (usually 24+ cans) at a time, give more satisfactory re- 
sults, relieving the monotony and preserving more successfully 
the keenness of observation of the inspector. 
The venthole filler is simple in construction, economical in 
operation and easily cleaned and kept in sanitary condition. The 
milk, from the time it comes within the range of the filler, 1s no 
longer exposed to contaminating influences, such as the hands 
of emploves, insects, ete. ‘The cans are uniformly filled to within 
one gram of the guaranteed weight and the vents or pin holes 
are automatically sealed with the minimum amount of solder. 
While the quantity of solder must necessarily vary with oper- 
ating conditions, it is possible to limit the average amount of 
solder, under proper conditions, to 5 ounces per 1000 cans, The 
