470 Canadian Record of Science. 
animal charcoal or by sulphurous acid gas. This will pro- 
duce brighter sugar, but we do not value this much, as the 
refiner, to whom the raw product is sold, buys it by its 
analysis and does not care much about a small difference in 
color. 
The pan is an iron or copper cylinder, furnished with a 
great number of steam coils and an air pump and con. 
denser. It may be any size almost, but usually is about 
nine feet in diameter and ten feet high. 
It is not an easy matter to boil sugar well if it be of a low 
grade, and long experience is valuable. In refineries, good 
boilers get high wages, for the yield depends much on them ; 
but they are commoner now than they used to be. The 
general operation is this. The pan is partially filled with 
liquor, and the steam turned on the lower coils so that 
the liquor is gradually boiled down till quite thick. Then 
the boiler opens the valve suddenly and takes in a small 
charge, shutting again quickly. The result is usually that 
crystals began to form in the pan, and after a little he takes 
in another charge. Sometimes, however, there is great 
trouble in forming the grain as we say, and charge after 
charge is taken in, and the amount carefully varied until at 
last wedo get some grain. Then the panman proceeds cau- 
tiously to nourish the grain which is at first very small, by 
carefully regulated charges. This done, the operation pro- 
ceeds more rapidly and all the panman has to do, usually, is 
to watch his vacuum guage and thermometer, and keep 
taking regular charges till the pan is sufficiently full. Then 
it is concentrated a little more and the work is done. The 
liquor has now become a thick sticky mass of syrup and 
sugar crystals of the consistency of putty, and brown 
in color. Had the syrup been boiled in the open air, it 
~would have been nearly black, but by reason of the vacuum, 
the temperature has been kept down to 150°, and may be 
kept as low as 110°, and it has merely got browned a little. 
The panman tests his pan by taking out little samples, and 
examining them on a piece of glass, or by feeling them and 
as soon as he is satisfied, he shuts off the steam, lets in the 
