excess of basic lead acetate. To determine the relative effect of the 

 sucrose and the excess of basic lead acetate in the formation of the 

 maximum maple lead precipitate, five series of determinations were 

 made, using less lead in each successive series. In the first deter- 

 mination of each series 25 grams of a pure maple sirup were used. 

 In the second determination of each series 5 grams of the same pure 

 maple sirup plus 20 grams of a pure cane sugar sirup were us*ed. In 

 the third determination of each series 5 grams only of the maple 

 sirup were used. In the second and third determinations there were 

 present, therefore, equal amounts of maple sirup, and the difference 

 in the amount of the precipitate formed was due to the solvent action 

 of the 20 grams of cane sugar sirup present in the second but omitted 

 in the third. 



Method of Procedure and Results. 



Introduce the quantity of sirup, maple or both maple and cane 

 sugar sirup as indicated in the table, into a 100 cc volumetric flask; 

 add distilled water, leaving room for subsequent addition of the lead 

 subacetate solution, which then add in the amount indicated; make 

 up to the mark, shake well and allow to stand three hours. Filter, 

 and determine the amount of lead in 10 cc of the clear filtrate by the 

 usual lead sulphate method. Standardize the lead solution in tne 

 same way but omit the sirup and add 5 cc of 10 per cent acetic acid 

 (see p. 3). 



The lead subacetate solution was introduced into the flasks from 

 25, 20, 15, 10, and 5 cc pipettes. In a given series the same amount 

 was added to each subtest but, since the pipettes were not calibrated 

 exactly or standardized among themselves, the quantity (25 cc) of 

 lead solution introduced into A was approximately but not abso- 

 lutely five times the quantity (5 cc) introduced into E, which ex- 

 plains the apparent slight discrepancy in the column giving the 

 amounts of lead added. 



Since the flasks were filled with water, leaving only sufficient room 

 for the addition of the lead subacetate solution, of the strength 

 specified by Winton, the results are comparable with those of Doo- 

 little and Seeker, who added smaller amounts of lead by first diluting 

 the strong solution and then adding 25 cc of the dilute solution. 



Each determination was made in duplicate, the average result 

 only being given. The maximum difference in the weight of the 

 lead sulphate on duplicates was 0.5 mg and the minimum 0.0 mg; 

 mean difference on 20 sets, 0.2 mg. x 



[Cir. 53] 



