H. E. ANNETT. 333 



Ammoniacal nitrogen. This was determined by the Sachsse- 

 Schloesing-Longi method by distillation of the juice with magnesia 

 at a pressure of 10 15 mm. and at a temperature of 35 ^"C. 1 



Amide and ammoniacal nitrogen. For this the juice was 

 heated in the water bath for 6 hours with dilute HC1 to hydrolise 

 the amides. The ammonia was estimated by distillation as in the 

 case of the ammoniacal nitrogen estimation. 



Albuminoid nitrogen. This was estimated by Stutzer's method, 

 that is, precipitation with copper hydrate and then estimating the 

 nitrogen in the precipitate by the Kjeldahl method. 



FACTORS INFLUENCING YIELD AND COMPOSITION OF THE JUICE. 



The data given in the tables on pages 322-23, have in the case of 

 four trees been plotted in curves (Charts 1 to 4), showing at a glance 

 the yield of juice as the season advances. A reference to the curves 

 brings out the interesting fact that they are of a similar type for 

 all the trees. For each tree the jiran, dokat and tekat yields have 

 been represented by separate curves. In general the yield is 

 smallest at the beginning of the season (Cf. curves, p. 7, Studies 

 of maple sap, by Morse, Bull. No. 32, New Hamps. Coll.). It 

 gradually increases to its maximum at about the third week in 

 January and then falls away again fairly rapidly till the end 

 of the season. 



Effect of climatic conditions, (a) Humidity. An attempt 

 was made to see if changes in the amount of moisture in the air 

 affected the yield of juice, but no useful results were obtained. 



(b) Temperature. It is agreed throughout the date sugar 

 districts, that the colder the nights, the richer and the more plenti- 

 ful is the juice. 



Newlands 2 records that in the case of the maple tree the 

 best yields of juice are obtained during cold clear nights following 

 bright warm days. 



1 Trans. Guinness Research Lab., Vol. 1, Pt. 1 (1903). 



2 Handbook for Sugar Planters, Newlands. 



