METAL SURFACES AND LIQUIDS IN CONTACT WITH THEM. 
75 
from the copper pipe a wronght-iron pipe is screwed into the casting, which is also 
surrounded by a water-jacket as shown. 
]’ig. 5. 
a 
During a set of experiments, \va,ter at a constant teinpeiuture is circulated up 
throug’h the inner pipe passing into the jacket tnrough the holes shown at the top, 
and then down the jacket. In this waj^, the length of the wrought-iron pipe remains 
L 2 
