$8 Chemical ^Examination of the Pollen 



acid with aimnonia, since lime and a caustic alkali extri- 

 cated from it extremely sharp ammoniacal vapours. In 

 truth it precipitated but very slightly by means of lime-wa- 

 ter, because it no longer contained phosphate, which former- 

 ly thickened the volume of the precipitates; but after having 

 added a certain quantity of brae-water, there were formed in 

 a few days large crystals of true malate of lime. 



But the liquor now under consideration was not entirely 

 formed of malate of ammonia j for upon exposing it to the 

 fire it exhaled an odour of burnt animal matter, in place of 

 a smell of caramel like pure malic acid ; besides, the in- 

 fusion of gallnuts formed in its solution an abundant brown 

 and viscous precipitate. Thus water applied to the pollen 

 of the date tree dissolved this animal matter by the inter- 

 medium of the malic acid; and what proves this is, that 

 when once the greatest part of the malic acid was taken up 

 by the alcohol, the phosphate of lime by being precipitated 

 took a great quantity along with it, which put this salt 

 nearly in the same state with that which fonns the saline 

 earthy calculi of the bladder, or the matter of the bones. 



§ VII. Remarks upon the Presence of the Phosphates of Lim6 

 and Magnesia in the Pollen of the Date Tree, and upon 

 their Solution in the Jqueous Ley of this Pollen. 

 The preceding experiments prove that phosphates of 

 lime and of magnesia were held in solution in the water 

 with which we had washed the pollen of the date tree ; never- 

 theless we know that these salts, and particularly that of 

 lime, are not soluble in water solely and by themselves ; but 

 as they are accompanied by malic acid, it appears certain, 

 that it is to this acid they owe their solubility. Thus, when 

 we wash with alcohol these matters, separated from water 

 and thickened into an extract by evaporation, this liquid 

 takes up a great quantity of the malic acid, and the residue 

 deposits as we have seen, on being dissolved in vvaler, a 

 portion of these salts, and particularly phosphate of lime, 

 which no longer finds a sufficient quantity of acid for being 

 soluble. Nevertheless it seems that a portion of malic acid 

 is combined intimately enough with the phosphates, and 



particularly 



