CANE SUGAE. 



Undetermined Losses. Sucrose per 100 cane, per 100 sucrose in cane and 

 per 100 sucrose in juice. 



The exact way in which the forms are scheduled is so largely a personal 

 matter, that the writer does not offer a scheme, but thinks it best to leave 

 this to each individual interested. 



Notes for Untrained Polarizers. The following notes on 

 laboratory work are intended for the use of factories where a resident chemist 

 is not employed. 



The Balance. A chemical balance differs in no wise except in extreme 

 sensibility from any commercial balance ; but owing to the delicacy of its 

 construction, it must be treated with extreme care ; a few minutes use by a 

 careless operator being sufficient to destroy its accuracy. Chemical balances 

 are enclosed in tightly fitting cases with glass sides, access to the interior 

 being given by a sliding door in front ; the object of this is to protect the 

 balance from damp and dust, and during weighing from draughts and other 

 disturbing causes. As a further protection from damp, it is advisable to place in 

 the balance a dish containing strong sulphuric acid or calcium chloride, which 

 will absorb moisture and keep the inside of the case dry. A chemical balance 

 consists essentially of an upright pillar, usually of brass, in which moves a 

 second pillar which can be raised or lowered by turning a milled head screw ; 

 the top of the moving pillar is a plane surface of agate or highly polished 

 steel ; on this plane surface rests the beam which carries the pans ; the beam 

 is supported on the plane surface by a knife edge of steel or agate ; the pans 

 also hang on knife edges at the ends of the beams ; when not in use the pans 

 rest on the balance case, and by turning the milled head screw the beam and 

 pans are raised, leaving the beam free to swing ; from the centre of the beam 

 passes vertically downwards a pointer, the end of which moves over a scale, 

 and by observing the swing of the pointer the operator can tell when the beam 

 itself swings evenly. 



When weighing on a chemical balance, determinations as to whether 

 exact balance is obtained are not made by letting the beam come to rest, but 

 by observing if the pointer swings through equal angles ; with a properly 

 sensitive balance it would take too long a time to let the beam come to 

 rest. 



The weights used in the laboratory are always gram decimal weights ; a 

 set will contain one 50 gram, one 20 gram, two 10 gram, one 5 gram, one 

 2 gram, two 1 gram weights, and so on down to '01 gram ; weights smaller 

 than this are so minute as not to be conveniently handled, and the following 

 device is used: The beam is divided into 100 equal parts, and a piece of wire, 

 called a rider, weighing exactly '01 gram, is arranged to be moved at will 

 along the beam, its effect being proportional to its distance from the fulcrum. 



512 



