168 THE ROYAL SOCIETY OF CANADA 



per cent., in the undiluted syrup; the maximum by 33 per cent., as 

 against 80 per cent., for the undiluted syrup. We have thus a total 

 range of 54 per cent., for the diluted, as against 129 per cent., for the 

 undiluted syrup. The forty-third syrup, omitted from the summary 

 in Table I, on account of its extremely low density, and high conductivity 

 gave a perfectly normal conductivity value (167) when diluted with 

 two volumes of water. 



The maximum conductivity, or, more strictly speaking, the con- 

 ductivity of the mixture of one volume of syrup with two volumes 

 of water is, accordingly, made the basis of the method here proposed. 



Method. 



Measure out into a small beaker (or directly into the conductivity 

 cell) a suitable quantity (15 c.c.) of the syrup, allowing thorough 

 draining. Using the same graduate, add two successive portions of 

 water, each equal in volume to the syrup taken. Mix thoroughly, 

 pour into conductivity cell, bring to 25° C, and make the measurement. 

 Divide the constant of the cell by the observed number of ohms and 

 multiply the result by 100,000. 



Genuine syrups have given values of 110 to 200, but further exper- 

 ience may extend these limits a little.* 



Syrups giving conductivity values distinctly outside these limits 

 may be condemned. Those giving noimal values are not necessarily 

 pure, and they should be further examined by well-established tests. 



Apparatus. 



The essential features of the apparatus are: — 



1. A low voltage electrical current operating an induction 

 coil. 



2. A conductivity cell of a form suitable for liquids of low 

 conductivity, and with electrodes not easily displaced. 



3. A Wheatstone bridge with telephone. 



4. A device for exact regulation of temperature. 



In the present work a Kohlrausch Universal Bridge bearing the 

 name plate of Messrs. Philip Harris & Co., Birmingham, England,! has 

 been used. The induction coil with which this bridge is fitted, was 

 operated by two lead accumulators, connected in series. A small 

 Deveau telephone was found to give better results than a Bell. With 



* I have collected nearly 130 syrups of the season of 1913 direct from the sugar 

 bushes of Ontario and Quebec and intend determining the limits of conductivity 

 value in these both at 25° and at 20° C. 



t No. 7072 in this firm's Physics Catalogue, \'ol. I. 



