American Milk- Condensing- Factories, 
123 
G by overflow g. The condensing water enters the condenser 
at E*, falls over the sieve-plates e e^, and comes in direct 
contact with the vapours, which have to pass also through the 
openings in the sieve-plates e^ e^, by which arrangement 
the greatest condensation is produced with the least amount of 
water. At E^, the vacuum-pipe, in this case a dry one, is 
connected. 
To prevent the condensing water from being drawn along 
with the vapours to the pump, the opening E^ is guarded by an 
apron. H is the pipe through which the liquor enters the pan. 
I is the drop-valve, composed of a rubber-disk i, between two 
plates on the end of the lever — a simple and most effective 
construction, the pressure of the outside air holding the valve 
perfectly tight ; i^ is a semi-globular casing, which prevents the 
liquor from spreading too much when it is discharged. On 
the end of the valve-stem is fastened a scraper J, intended to 
break any crust of crystallised sugar that may have formed, as 
any such crust, unless removed, would, of course, obstruct the 
exit of the liquid. 
The regular mountings of the pan consist of a man-hole ; a 
thermometer L, the tube of which is enclosed in a pipe 7, and 
reaches to the centre of the boiling liquor ; a vacuum gauge M ; 
a glass gauge K, by means of which the quantity of liquor in the 
pan is observed ; a butter-cup N — butter quieting the liquor if it 
shows a tendency to boil over ; an eye-glass O, opposite to which 
is another similar glass, through which a lamp gives light to the 
interior of the pan. Q is a light glass on the top of the pan, 
through which the entire surface of the boiling liquor may be 
illuminated, and R is the tester, by means of which proofs are 
drawn to see how far the process has advanced. 
Heat is applied in the following manner : — the botton of the 
pan is double, and steam is admitted thereto by the pipe P, 
the upper shell, which forms the heating surface, being generally 
of copper. The steam also passes through one, two, three, or 
even four coils, according to the size of the pan, and the amount 
of water to be evaporated in a specified time. P is the steam 
branch. The pipe S leads to the bottom, to the lowest coil, 
to the middle coil, and to the upper one. As fast as the 
steam is condensed the water is led by the pipes U U from 
the bottom, and coils to a steam trap. 
It might, at first, be supposed that cast iron would fail to 
resist the corroding action of solutions, but the results of practice 
show that the scale, which in every case covers the metal, pro- 
tects the pans completely. And as the liquor is in all cases 
charged to some extent with lime, the pan speedily becomes 
covered with a fine scale or fur, which effectually prevents all 
