The solution should be standardized each time a set of determinations is made, 

 although it is claimed that there is no deterioration in this solution for a month. 



Description of method. Weigh 25 grams of the material (or 26 grams, if it is desired 

 to determine sugars by polariscope in the same portion) into a 100 cc flask. Add 

 25 cc of standard lead subacetate solution, fill to the mark, shake, allow to stand at 

 least one hour, and filter. From the clear filtrate pipette off 10 cc, dilute to 50 cc, 

 and add a moderate excess of sulphuric acid and 100 cc of 95 per cent alcohol. Let 

 stand over night, filter on a Gooch crucible, wash with 95 per cent alcohol, dry at a 

 moderate heat, ignite at low redness for three minutes, taking care to avoid the redu- 

 cing cone of the flame, and weigh. Calculate the amount of lead in the lead sulphate 

 precipitate by the factor 0.6829, subtract the result from the amount in 2.5 cc of the 

 standard solution (or from the amount found in the blank), and the figure obtained 

 will be the amount of lead contained in the lead precipitate of organic matter. Divide 

 this number by 2.5 and multiply by 100, to obtain the lead number or the per cent 

 of lead precipitated by 1 gram of the original sample. (In case 26 grams are used, 

 this last divisor should be 2.6 instead of 2.5.) 



The figures for pure maple sugar vary from 1.83 to 2.48; average, 

 2.23. 



The figures for pure maple sirups vary from 1.19 to 2.03; aver- 

 age, 1.49. 



Adulterated products are generally much lower. 



V. PER CENT ASH (TOTAL). 



Weigh 5 grams of sirup or sugar into a tared platinum dish; heat over asbestos 

 board until the contents are thoroughly carbonized; transfer to a muffle and burn 

 at low red heat to a white or gray ash. Cool on desiccator and weigh quickly.* The 

 final ashing can be accomplished over an ordinary bunsen burner, and in most cases 

 this is to be preferred to a muffle, as there is less danger of loss of ash by overheating. 

 If considerable frothing occurs during the first drying and burning, place a few drops 

 of pure olive oil on the sample during burning. Divide the weight of ash by 5 and 

 multiply by 100 to obtain the percentage of ash. 



The rate of burning and kind of ash are indicative of purity. 

 Adulterated articles, as a rule, take longer to burn and produce an 

 ash hard to rid of the final particles of carbon. Pure maple ash is 

 grayish, sometimes greenish, in color and often has a network structure 

 like the veining of a leaf. According to the food standards, maple 

 sugar should not contain less than 0.65 per cent of ash and maple 

 sirup not less than 0.45 per cent of ash. The average figures com- 

 piled from the sources mentioned are as follows: 

 Pure maple sugar percentage of total ash : 



Jones. _ . 0.64 to 1.32; average, 0.91 

 Hortvet 0.65 to 1.30; average, 0.91 



Pure maple sirup percentage of total ash: 



Jones. __ . 0.50 to 0.86; average, 0.60 



Hortvet_ . __ 0.52 to 1.01; average, 0.68 



Bureau of Chemistry. _ . 0.46 to 0.86; average, 0.60 



[Cir. 40] 



