163 



CONSTRUCTION OF APPARATUS. 



liquid poured in the vessel ; at most a few drops will escape very 

 slowly, and nothing whatever if the edge of the cylinder be very 

 slightly rubbed over with a drop of oil. Cylinder 3 requires a little 

 more pressure than the others to make it adhere. The cylinders 

 1 and 2 must now be provided at their upper end with metal collars, 

 l cm wide. Cut a strip of sheet zinc or brass, so thin that it may be cut 

 with the scissors, and make it about 3^ times as long as the external 

 diameter of the cylinder at the top. Bend it into a ring which slips 

 easily over the cylinder, and solder the ends together ; if zinc is used 

 take care not to melt it, especially when heating it over a Bunsen's 

 burner. Two holes are drilled in the ring, opposite to one another. 

 The most convenient form of drill for such small holes is shown in 

 fig. 118. To avoid bending the ring out of shape while marking the 

 holes with the centre-punch and drilling them, the ring is placed 



FIG, 118 (real size). 



FIG. 119 (an. proj. g- real size}. 



upon a rounded piece of wood, which is clamped horizontal!} 

 between the cheeks of the vice, so as to project partly, as shown ir 

 fig. 119. The breastplate cannot in this case be pressed agains 

 the chest, but is held with the left hand, while the right move. 1 

 the drill-bow. The holes must be nearer to one edge of the rim 

 than to the other, as seen in fig. 120, which shows the vessels in th<j 

 finished state. The upper rim of each vessel is now heated verjl 

 cautiously over a lamp, turning the cylinder continually whil<| 

 heating, until sealing-wax melts upon it, and the rim is covered witl 

 a layer of it of about l mm in thickness ; when the whole has cooled 

 the ring is also heated to the temperature at which sealing-wax melt: 

 upon it, and pushed while hot over the rim, but only so far as to leav< 

 the holes free ; the wax which has been squeezed out along the edge i 

 scraped off, after it has cooled, with a knife. Handles of brass win 



