170 THE ROYAL SOCIETY OF CANADA 



and a much lower ran<;e than those shown by the soluble ash, the 

 insoluble ash and the alkalinities. 



Table IV includes analytical data for twelve of the Quebec syrups 

 included in the summary given in Tal)le I. These were examined to 

 determine whether this apparent advantage of the conductivity method 

 held for syrups of vaiious origin, as well as for those from a single bush. 

 It will be seen that among these 12 syi'ups the range of the conductivity 

 value is much narrower than that of the total ash and narrower 

 also than that of any of the other data except the Canadian lead 

 nuntber. 



If this narrowness of range shall bo found to be characteristic of the 

 conductivity values of pure maple syrups in general, it will be a point 

 of advantage for this method. 



I have also examined three syrups made at the Vermont Agricul- 

 tural Experiment Station under the supervision of Prof. C. H. Jones, 

 who advised me that they were prepared with great care "every oppor- 

 tunity being given for the malate of lime to settle out." These syrups 

 were exceptionally light in colour. As received they were of exception- 

 ally high density, as indicated by Prof. Jones's refractometer readings, 

 viz., No. 1 at 24]°; 1-4632; No. 2 at 21^°; 1-4651; No. 3 at 24|°, 

 1-4623. For my own anal3^ses they were diluted with water, boiled 

 to a boiling point of 219-220°F., and filtered through double S. & S. 

 No. 597 filters.* Their densities at 15°C were then 1-325, 1-321 and 

 1-332 respectively. Two of these Vermont syrups gave lower conduc- 

 tivity values than any of the Canadian syrups, viz., 110 and 115. The 

 third gave a value of 122. The ash values of these three syrups were 

 also exceptionally low. Complete data for these syrups, as obtained 

 by Professor Jones and myself, are given in Table V. 



110 is the minimum value yet found in a genuine syrup. The max- 

 imum of 203 obtained with the syrup prepared in the iron kettle has not 

 been reached in any other pure sj^rup. The highest value yet found in 

 a syrup actually prepared for the market is 197. The limits of variation 

 of the conductivity value of genuine syrups may, therefore, be tenta- 

 tively set at 110 to 200. 



The mean conductivity of the 68 syrups may most fairly be esti- 

 mated by giving the mean of the 22 syrups made from the trees on the 

 Macdonald College Farm a weight of 2 — the same as one pair of early 

 and late run syrups. AVe thus obtain for the 48 syrups — 46 actual 

 and 2 theoretical — a mean conductivity value of 150. This is approxi- 

 mately equal to the electrical conductivity of an -01 M aqueous solution 

 of potassium chloride (141-2). 



* Jones, Vt. Agr. Expt. !Sta. 18tli Annual Report, p. 328, (1905): also Bulletin 

 167, p. 470, (1912). 



