02 Chemical Examination of the Pollen 



trous and carbonic acid gas. Some time after boiling, an 

 oily substance was formed of a yellow colour, which swam 

 on the surface of »be liquor. The quantity of this fatty 

 matter seemed to increase as the ebullition went on, but it 

 seemed to decrease latterly ; we then removed the mixture 

 from the fire. When it was cool the fatty substance be- 

 came fixed, forming a thick coat on the liquor, which was 

 of a very deep yellow, similar to the colour communicated 

 by the nitric acid to all animal substances treated iu the 

 same manner. 



This liquor had a very bitter taste, and a smell like that 

 of prussic acid, although it was impossible to ascertain the 

 presence of this acid. 



The colouring matter thus formed by the nitric acid ad- 

 hered strongly to pieces of cloth, and particularly to fabrics 

 of an animal nature, and was extremely fixed. 



The nitric solution mixed with the alkalis until the excess 

 of acid was saturated, assumed an orange yellow colour, 

 much deeper, and precipitated earthy phosphates and ox- 

 alates, charged with a portion of the colouring matter ; an 

 excess of alkali makes the orange colour change to a blood 

 red. 



This same liquor left, upon being properly evaporated, 2 

 reddish yellow substance, very bitter, tenacious, and gluey, 

 perfectly soluble in water, to which it communicated a ci- 

 tron shade, giving a precipitate of oxalate of lime upon the 

 addition of ammonia, and ammonia by its mixture with the 

 caustic alkalis. 



The action of the nitric acid upon the pollen of the date 

 tree had therefore formed, 1st, ammonia; 2d, carbonic acid; 

 3d, oxalic acid; 4th, a yellow matter, bitter, and soluble in 

 water; 5th, a kind of suet or fat matter. This last, v.'hen 

 washed several times with warm water, was of a greenish 

 vellow colour, a bitter taste, weaker, however, than that of 

 the liquor from which it had been separated : it became white 

 upon being dried in the air. 



It became soft iu the fingers, to which it stuck like 

 liquid and tenacious resins. By heat it was melted into a 

 yellow liquor, at the bottom of which there were some solid 



bodies 



