MAPLE SIRUP PRODUCERS MANUAL 



83 



PN-4794 



Figure 9S. — Checking the density of sirup with a refrac- 

 tometer. Only one drop of sirup is required for this 

 measurement. 



and it is best suited for use by the sirupmaker. 

 All that is required to make precise density 

 measurements is a relatively inexpensive but 

 accurate hydrometer, a thermometer, and a 

 hydrometer tube or jar (fig. 99). Hydrometry is 

 based on the Archimedes principle that the 

 density of a liquid can be measured by the 

 displacement of a floating body. The hydrome- 

 ter, a partly immersed body, displaces a volume 

 of liquid having a mass equal to the weight of 

 the hydrometer. A hydrometric measurement 

 is made by noting the point on the hydrometer 

 stem that is in contact with the surface of the 

 liquid. The hydrometer must be at rest and 

 floating freely in the liquid, as shown in chart 

 19. The density value is read from a scale sealed 

 in the stem. 



The accuracy of a hydrometer measurement 

 depends on the spacing of the markings on the 

 scale in the hydrometer stem, which in turn 

 depends on the diameter of the stem. Thus, the 

 thinner the stem, the farther apart the mark- 

 ings, and the greater the accuracy with which 

 the density measurements can be made. The 

 scale of hydrometers for measuring density of 

 sirup may be marked and calibrated in or on 

 the stem of the hydrometer (chart 20). These 

 scales can be marked by one of three systems or 

 a combination of the systems: (1) Specific grav- 

 ity; (2) Brix scale; or (3) Baume scale. 



HYD ROMETER STEM 



7^ 



READING 

 POINT 



Chart 19. — Hydrometer used for measuring density. The 

 hydrometer can should be filled to the top. It should be 

 held at eye level for reading. 



Both specific gravity and the Baume scale 

 relate the weight of a unit volume of maple 

 sirup (the solution being tested) to some other 

 liquid used as a standard; they give no direct 

 information regarding the solids content of the 

 sirup being tested. 



Brix Sfdif 



The Brix scale relates the density of sirup to 

 sugar solutions of the same density and known 

 percentages of sugar. The Brix value does not 

 express the true percentage of sugar in a solu- 

 tion containing sugar plus other dissolved sol- 

 ids; rather, it indicates what the percentage of 

 sugar would be if the density of the solution 

 were due only to dissolved sugar. The Brix 

 scale is particularly well suited for measuring 

 the density of maple sirup because 98 percent of 

 the dissolved solids is sugar. For practical pur- 

 poses, the Brix value equals the percentage of 

 sugar in the sirup. 



