126 BACTERIA IN RELATION TO PLANT DISEASES. 
is good, but when it is feeble or when the steam pressure is high the water becomes 
too hot and steam sometimes escapes into the reservoir. The water therefore must 
be hurried through the tank by the use of a steam pump, or else less steam must 
be allowed to enter the copper pipe. If the writer were to build another similar 
apparatus he would make the condensing tank 2 feet higher and add ro feet to the 
length of the coil of tin pipe. The condensing tank is provided at the bottom 
with a 1-inch inflow pipe for the cold water (it should be 1%-inch), and at the top 
with a 14-inch outflow pipe (it should 
be 2-inch), for the exit of the warmed 
water. There is also a 1-inch flush 
pipe at the bottom for the occasional 
removal of sediment. 
The size of the outflow pipe, which 
must be somewhat larger than the in- 
flow pipe, prevents any possibility of 
clogging and overflow. ~All the metal 
parts which come into contact with the 
distilled water are tinned or nickel- 
plated. Connected with the lower end 
of the block-tin coil (by tin solder, 
which must not contain lead or zinc) 
is a smaller (%-inch) block-tin pipe 
(11), which leads the distilled water into 
(15) the storage tank (34-inch pipe 
would be better, and without any joint). 
The reservoir in this case is a white- 
enameled bath-tub, on the top of which 
is clamped down a cover of thin sheet 
copper (‘)-inch), the inner face of 
which has been carefully tinned. Plate 
glass ground to fit would be better, and 
the tub itself is likely to be discarded 
in the near future, z e, when some 
more satisfactory storage tank can be 
found. The problem of the proper 
storage of distilled water in quantity is 
the hardest one, the solvent power of the 
water is so great. From the bottom of 
this bath-tub several hundred feet of %-inch block-tin piping lead to various rooms 
in the building. In addition to the terminal faucets there is a general cut-off just 
above 18, which is necessary in case of an accident to any faucet or part of the 
piping. ‘There is also an overflow pipe (17), which does not enter the sewer, but 
*Fic. 118.—Early stage of stomatal infection in angular leaf-spot of Rivers cotton. Hothouse 
infection produced by spraying Bacterium malvacearum upon the surface of the leaves. For a much 
later stage see fig. 80. 
