DISCUSSION OF CHEMICAL DATA. 63 



bv this method the thermometer must be accurate and must be held 

 in the boiling liquid so that it does not touch the sides of the metal 

 evaporator or pan. A good rule for the maker to follow when using 

 a thermometer is to test it in boiling water and note the temperature ; 

 the sirup should boil at a temperature 7 higher than that of boiling 

 water if it contains 35 per cent of water, or 9 higher if 32 per cent 

 of water is present. 



A hydrometer or Baume spindle should never be placed in boiling 

 sirup as this destroys the accuracy of the instrument. Only cold 

 sirup should be tested by this method, especially when the ordinary 

 glass hydrometer is used; a metal one is not so much affected by 

 heating. The diameter of the vessel containing the sirup should be 

 at least 2 inches, so that the spindle does not come in contact with 

 the sides. For 35 per cent of moisture, the Baume reading is 35.6 

 and for 32 per cent of moisture 37.1 B. In Canada the imperial 

 gallon (277.274 cubic inches) is the standard and hence maple sirup 

 there must weigh 13 pounds and 2 ounces for a water content of 35 

 per cent. 



SUCROSE. 



The average figures for the sucrose determination in the United 

 States samples is 62.64 per cent, in the Canadian samples 62.24 per 

 cent, the average of all being 62.57 per cent. Reducing these figures 

 to the dry basis it is seen that sucrose constitutes about 95 per cent 

 of the solid matter, amounting approximately to 95.2, 94.8, and 95.1 

 per cent for the three groups mentioned. The variations in the 

 sucrose content range from 47.20 to 70.46 per cent for the United 

 States samples alone. Generally a low sucrose content is accompanied 

 by a high reducing sugar content, indicating that the sirup has 

 fermented or lias been prepared from sour sap. 



INVERT SUGAR. 



The method followed for making this determination takes into con- 

 sideration the reducing action of sucrose on the alkaline copper 

 solution, otherwise the quantity of reducing sugars as determined 

 would contain a large positive error. The extreme figures for this 

 determination are zero and 11.01 per cent, the latter representing 

 a fermented sirup. The average was 1.47 per cent of invert sugar. 

 About 53 per cent of the sirup samples contained less than 1 per cent 

 of invert sugar, as shown in the following table: 



