MAPLE SUGAR. 9 



In experiments 1 and 2 the results of burning in the three different 

 ways are the same when the heat is low. When, however, the heat 

 is increased, the percentage drop is 0.05 per cent in experiment 1 and 

 0.07 per cent in experiment 2, but the addition of ammonium car- 

 bonate brings the results back to the normal. In these two cases the 

 extra heating has caused the formation of the oxid from the carbon- 

 ate, but has not volatilized any of the ash. Repeating experiment 1 

 with a much greater heat, the ash drops 0.22 per cent and comes back 

 only 0.03 per cent when moistened and reburned. Similar results 

 were obtained in experiments 4 and 5, in both of which the percent- 

 age of ash did not come up to the normal by heating with ammonium 

 carbonate. All three show the volatilization of some of the ash. 



This all shows the necessity of using the utmost care in carrying 

 out this determination. A very dull red is the highest to which an 

 ash should be heated; then ammonium carbonate should be added 

 and the dish reheated for true results. 



LEAD NUMBER. 



Two determinations of the lead number were made, using basic 

 lead acetate solution in both. The lead number using normal lead 

 acetate, as described in Bureau of Chemistry Bulletin 134, page 17, 

 was not determined on these samples. The ordinary Winton lead 

 number determination 1 was made and also the modification by S. H. 

 Ross, 2 which is as follows : 



Transfer 25 grams of the sirup to a 100 cc flask, using about 25 cc of distilled water; 

 add 10 cc of potassium sulphate solution (7 grams per liter), 3 then 25 cc of lead sub- 

 acetate solution of the strength specified by Winton. Make up to the mark, shake 

 thoroughly, and allow to stand 3 hours. Filter, rejecting the first portion of the fil- 

 trate. Pipette off 10 cc of the clear filtrate into a 250-cc beaker, dilute to 50 cc, add 

 2 cc of 20 per cent sulphuric acid and 100 cc of 95 per cent alcohol. Let stand over- 

 night, filter off the lead sulphate on an ignited, weighed Gooch crucible, wash with 

 95 per cent alcohol, dry, ignite at low redness for 3 minutes in a muffle or over a burner, 

 taking care to avoid reducing cone of the flame, and weigh. Run a blank in exactly 

 the same way, substituting 25 grams of a pure cane sugar sirup (66 per cent sucrose 

 content) in place of the sirup to be tested .* Subtract the weight of the lead sulphate, 

 obtained from 10 cc of the sirup test filtrate, from that obtained from 10 cc of the 

 cane sugar sirup blank filtrate. The remainder, expressed in grams and multiplied 

 by 27.325, gives the modified Winton lead number. 



In both of these tests the composition of the lead subacetate solu- 

 tion is of the greatest importance, as it greatly influences the lead 

 number. The average results of the basic lead acetate and normal 

 lead acetate lead number taken from the work on sap sirups, 5 2.70 



J U. S. Dept. Agr., Bur. Chem. Bui. 134, p. 17. 



2 U. S. Dept. Agr., Bur. Chem. Cir. 53. 



3 Freshly boiled distilled water should be used throughout. 



* Do not use acetic acid in this blank; acidified blank is suggested for use only with original Winton 

 method, 

 s U. S. Dept. Agr., Bur. Chem. Bui. 134, p. 89. 



61390°— 17— Bull. 466 2 



