H. E. ANNETT. 343 



Mercuric chloride.- The experiments shew this to be a very 

 effective preservative. By an oversight however much larger 

 amounts of the substance were used than are really required. 



ACIDS PRESENT IN DATE JUICE. 



About 6 litres of preserved juice free from fermentation were 

 distilled in steam after acidifying with 0'5 per cent, of sulphuric acid. 

 About 4 litres of distillate were collected. The distillate was practi- 

 cally neutral and was not further examined. The residual liquid 

 in the flask was extracted with ether in a large separating funnel. 

 About 15 c.c. of the liquid was shaken with about 200 c.c. of ether 

 at each extraction until all the liquid had been so treated. The 

 whole process of extraction was gone through in a similar way with a 

 fresh lot of ether. The ether extracts were then combined and the 

 ether distilled off. About one half of a c.c. of a tarry liquid of a 

 very bitter taste was left behind together with 7 or 8 small clusters 

 of crystals. Attempts to purify the crystals failed as they were 

 present in such small quantity only a few milligrams at the most. 

 They were readily soluble in water and alcohol, and had an acid re- 

 action and a cooling sharp taste. On examination under a micros- 

 cope fitted with a polarising apparatus the crystals were seen to be 

 needle-shaped and gave interference bands on rotating the Nicols ; 

 the play of colours being very brilliant. Crystals of malic acid 

 appeared to be of the same crystalline form and behaved in a similar 

 manner under polarised light. Only one form of crystal was 

 observed. On solution in water and addition of neutral lead 

 acetate a curdy precipitate was obtained. 



Attempts to recover the free acid by decomposition of the lead 

 salt with hydrogen sulphide failed. 



CAUSE OF ALKALINITY OF THE JUICE. 



It has already been stated that date palm juices when first 

 drawn from the tree are alkaline to litmus paper. ' The quite fresh 



1 The sap of the Buri palm (Corypha elata) has been shewn to be alkaline when freshly 

 drawn. (See Gibbs "The Alcohol Industry," Part I, Philippine Jour, of Science, June 1911, 

 Series A, p. 176.) 



