MAPLE SUGAR. 11 



much above the true lead number, while solutions 3 and 7 are below 

 the true results. Solutions 1 and 6 contain more litharge in pro- 

 portion to lead acetate than solutions 3 and 7, and likewise show 

 a greater alkalinity. The alkalinity of the solution plays an im- 

 portant part, for when there is practically no alkalinity, as in No. 

 8, the lead number drops to an average of 0.35. 



By preparing the solution of basic lead acetate strictly according 

 to the method outlined in Bureau of Chemistry Bulletin 107, Revised, 

 or in Winton's original method, or by solution of Home's dry lead 

 subacetate, the results of analysis should be comparable and easily 

 duplicated. The acidity of the sample itself has little effect on the 

 lead number, as shown in Table IX. 



Table IX. — Winton lead number of sirup before and after neutralization. 

 [Not calculated to dry basis.] 



Sample. 



No. 8451. 



No. 9235. 



Straight sirup 



Sirup after neutralization . 



1.75 



1.78 



1.49 

 1.56 



In both samples the lead number was determined on the original 

 sample and again on the same sample after neutralizing the acidity 

 with tenth-normal potassium hydroxid, using phenolphthalein as 

 an indicator. The acidity in one case, No. 8451, equaled 1 cc, in 

 the other, No. 9235, 3 cc, of the tenth-normal potassium hydroxid 

 to 100 cc. The neutralization increased the lead number by only 

 0.03 and 0.07, respectively. 



MALIC ACID VALUE. 



The calcium acetate method proposed by Cowles 1 was used for 

 this determination. In the Bureau's previous work, it had been found 

 that the blanks with calcium acetate were more even and the pro- 

 cedure indicated for this method gave a good precipitate which 

 settled easily. The procedure is as follows: 



Weigh 6.7 grams of the sample in a sugar dish, transfer to a 200-cc beaker with 

 5 cc of water, add 2 cc of a 10 per cent calcium acetate solution, and shake. Stir 

 in 100 cc of 95 per cent alcohol and warm the solution until the precipitate settles, 

 leaving the supernatant liquid clear. Filter off the precipitate and wash with 75 

 cc of 85 per cent alcohol, dry the filter paper, and ignite in a platinum dish. Add 

 10 cc of tenth-normal hydrochloric acid and warm gently until all the lime dissolves. 

 Cool and titrate back with tenth-normal sodium hydroxid, using methyl orange as 

 an indicator. One-tenth of the number of cubic centimeters of tenth-normal acid 

 is the malic acid value. Run a blank determination with each set of determina- 

 tions, using the same amount of reagents, and subtract the result obtained from 

 the malic acid number. 



O ■ — , . 



1 Jour. Amer. Chem. Soc, 30 (1908), p. 1285. 



