Decembee 31j 1915] 



SCIENCE 



947 



that from another mixed syrup contained 70.11 

 per cent. (6) Titration of maple syrup with 

 N/50 silver nitrate (a) directly, using electrical 

 resistance measurements to detect the end point 

 (b) after treatment with lead subaeetate, or 

 alumina cream, using potassium chromate as indi- 

 cator yielded definite but not useful results. (7) 

 Titration with uranyl acetate gave no useful re- 

 sults. (8) Titration with lead subaeetate solu- 

 tions using electrical resistance as indicator led 

 to a useful method of testing the syrup for purity, 

 which is described in the next paper of the series. 

 A Volumetric Lead Subaeetate Test for Purity of 



Maple Syrup: J. F. Snell, N. C MacFarlane 



AND G. J. Van Zoeeen. 



(1) The volumetric lead subaeetate test consists 

 in diluting the syrup to ten times its original vol- 

 ume and titrating with lead subaeetate solution of 

 sp. gr. 1.033, obtaining the end-point by measure- 

 ments of electrical resistance. (2) The volumetric 

 lead number is the abscissa of the point of inter- 

 section of two straight lines on the plot of vol- 

 umes as abscissa with resistance as ordinates. 

 (3) Seventy genuine Quebec 1914 and 1915 syrups 

 gave volumetric lead numbers ranging from 4.8 

 to 6.6 — a range of 37.5 per cent, of the mini- 

 mum as compared with 97 per cent, for the con- 

 ductivity value. Twenty-eight of these syrups 

 showed a range of 75 per cent, for the conductiv- 

 ity value and 339 per cent, for the Canadian lead 

 number, while the range of volumetric lead num- 

 ber was the same as in the whole 70. (4) Seven- 

 teen out of 20 syrups containing 30 per cent, of 

 sucrose syrup gave smooth curve plots. Eighteen 

 out of 20 containing 40 per cent, sucrose syrup 

 gave smooth curves and the remaining two gave 

 intersections outside the limits for genuine syrups. 

 Of 14 adulterated and non-maple syrups 10 gave 

 smooth curve plots, 2 gave intersections outside 

 the limits found in genuine syrups and in the re- 

 maining 2 (cane molasses) the electrical resist- 

 ance remained constant. 

 The Electrical Conductivity Test for Purity of 



Maple Syrup. Corrections and Supplement to 



Paper I.: J. F. Snell. 



(1) A number of minor corrections to paper I., 

 as published in the Journal of Industrial and 

 Engineering Chemistry, are noted. (2) The di- 

 rections are modified to suit a new type of elec- 

 trode. (3) Experience with the test has shown 

 that the limits of variation of the conductivity 

 value in genuine syrups are wider than appeared 

 when paper I. was published. However, these lim- 

 its are still narrower than those of any of the 

 older analytical values. 



The Determination of Total Solids in Milk hy 

 Open-Air and Vacuum Methods: Geo. Geindrod. 

 Results obtained by several different methods of 

 •drying are given and the methods compared as to 

 accuracy. Moisture absorbed by milk residues 

 was found to cause them to lose weight when 

 further heated. Eepeated weighing till minimum 

 weight is reached, as usually practised, is liable 

 to cause erroneous results on account of moisture 

 absorbed during weighing. Eepeated analyses of 

 samples from the same lot of condensed milk over 

 a period of one year show atmospheric pressure 

 drying subject to error. Vacuum apparatus espe- 

 cially adapted to determination of total solids in 

 milk is described. Results by this apparatus found 

 more accurate than other methods. 



DIVISION or PHYSICAL AND INORGANIC CHEMISTRY 



G. A. Hulett, Chairman 



R. C. Wells, Secretary 



Anodic Relations of Passive Iron: H. G. Byees 



AND SeTH C. LaNGDON. 



Electrolytic Endosmose: Ruby Clift and George 



Glockler. 

 The Stabilising Influence of Hydrogen Sulfide on 



Colloidal Metallic Sulfide Solutions: S. W. 



Young. 

 Equilibria Internary Systems containing Alcohols, 



Salts and Water: George Bell Feankforter 



and Sterling Temple. 



A study was made of the use of some salts to 

 determine the per cent, of alcohols in mixtures of 

 alcohol and water by means of the amount of salt 

 which could be added without causing a separa- 

 tion into two layers. Curves were drawn and di- 

 rections given for the use of the method. The 

 following systems were investigated: Propyl 

 Alcohol-Sodium Carbonate-Water, Isopropyl Alco- 

 hol-Potassium Fluoride-Water, Isopropyl Alcohol- 

 Potassium Carbonate-Water, Allyl Alcohol-Potas- 

 sium Fluoride-Water, Allyl Alcohol-Potassium 

 Carbonate-Water, Allyl Alcohol-Sodium Carbon- 

 ate-Water and Allyl Alcohol-Sodium Chloride- 

 Water. This work together with the work of 

 Frankforter and Prary indicates that potassium 

 fluoride and potassium carbonate can be very suc- 

 cessfully used for a quick method of determining 

 the strength of solutions of ethyl, propyl, iso- 

 propyl and allyl alcohols. The evidence did not 

 support the hypothesis that the salting out power 

 of a salt could be predetermined from a knowl- 

 edge of the ions in the solution, but showed tha.t 

 it was rather a function of the amount of water 

 which the salt took up to form its hydrates, the 



