418 On the State of the Manufacture 
deep, till it is one-third full, and is then heated to ebuilition, 
which is kept up to the end of the operation. If it chance to 
burn, it is perceived by puffs of white simoke, which come from 
the bottom of the boiler, and burst through the surface of the 
liqnid, spreading a pungent smell; the fire must be slackened, 
the liquor stirred, aud the operation more carefully attended to. 
This accident was common three years ago, but by following the 
aforesaid process it is now become very rare. If the boiling 
mass swells, rises, and froths, it may be moderated by putting 
into it a small piece of butter, or by slackening the fire. The 
means of judging that the operation is going on well are, first, 
when it boils dry and with noise; secoudly, when the syrup de- 
taches itself from the skimmer without drawing into threads, and 
without adhesion ; thirdly, when on striking the boiling mass with 
the back of the skimmer, the blow sounds dry, as ifit struck upon 
silk ; fourthly, when it produces very little skim; fifthly, when 
on taking up some of the froth or the bubbles out of the boil 
with the skimmer, the bubbles disappear directly and resolve into 
liquid: this latter character distinguishes the bubbles of the boil 
from those of the scum; lastly, we may be satisfied that the 
operation has proceeded well, if no traces of black can be per- 
ceived at the bottom of the boiler, and the surface appears 
clean. 
The time proper to terminate the boiling of the syrup may be 
known by the following indications: first, by dipping the skim- 
mer into the syrup, and on taking it out again pass the thumb 
rapidly over the edge, in order to take up a little of the syrup; 
work this drop of syrup between the fore finger and thumb, 
till it has acquired the temperature of the skin; then separate 
the finger and thumb rapidly: when it does not draw into a 
‘thread between the fingers the operation is far from being con- 
cluded ; when it begins to form a thread the operation is far 
advanced, and then the experiment must be frequently repeated. 
The boiling must be discontinued the moment that the thread 
breaks dry; in this case the upper part of the broken thread 
shrinks towards the fore finger, ferming a screw, and is never 
entirely lost in the mass that adheres to the finger. As soon 
‘as it is ascertained by this fes¢ that the operation of boiling the 
syrup is completed, the fire is smothered, and a few minutes af- 
terwards it is poured into the cooler, taking care to pour it high, 
that it may be mixed with air, for it is observed that this facili- 
tates the crystallization. 
Into the vessel called the cooler is poured the whole of the 
successive products obtained by the different boilings completed 
in one day. 
In the evening, when the whole is thus collected in the cooler, 
the 
