W. A. Davis, A. J. Daish and G. C Sawvei; :>1.") 



APPENDIX. 



A. Example showing Method of Calculating Results. 

 Mangold Leaves. October 11th, 1912, II p.m. 



The alcoholic extract of the leaf material was evaporated in vacuo 

 and made up to SOU cc. 



20 cc. of the .500 cc. evaporated and dried in vacuo at 110° in the 

 apparatus, Fig. 2, gave (a) 2-5833 grms. 



(b) 2^872 „ 



Average = 2-5852 grms. = 64-63 grms. in 500 cc. 



The leaf residue left after extracting the sugars, etc., weighed 

 75-31 grms. after drying at 100". This still contained 6-84 % moisture, 

 as determined by heating 10 grms. */( vacuo at 110° (see p. 269). 



.". Weight of vacuum-dried matter in the 75-31 grms. = 75-31 0-931G 



= 70-16 grms. 

 Total vacuum-dried matter in leaf sample = 64-63 -i- 70-16 



= 134-79 grms. 



Matter extracted by alcohol 6-4-63 ,„„ .„ ^ „, 



■: ^= y 100 = 47-9 ' 



Total vacuum-dried matter 134-79 '' ^°' 



For sugars. 



440 cc. of the 500 cc. were precipitated by basic lead acetate (265 cc). 

 filtered and washed to 2 litres = Solulion A. 



300 cc. of A deprived of lead by solid sodium carbonate and made 

 to 500 cc. = Solution B. 



For reducing sugars. 



25 cc. of B (=15 cc. A) gave 0-2210 grm. CuQi. 



Rotation of Solution B in 200 mm. tube at 20° (Na fiame) = + 0-274°. 



For cane sugar. 



■50 cc. of Solution B were inverted by either citric acid or invertase. 

 After inversion and neutralisation, made to 100 cc. = Solution C (or C") 



(a) Citric acid. 



.50 cc. of C (= 25 cc. B = 15 cc. .4) gave 0-3710 grm. CuO. 

 Solution C gave rotation = - 0-064° in 200 mm. tube at 20°. 



' In all cases the value of the cupric reducing power giren is the average of two or 

 three closely concordant results. The separate determinations always agreed to within 

 1 to 2 mgs. of CuO. 



