160 PLANT AND ORGANIC CHEMISTRY 



orated over a water-bath until all odor of sulphuretted hy- 

 drogen was dissipated. A part of the lead sulphide nitrate was 

 mixed with lime-water, and a precipitate formed not com- 

 pletely dissolved by acetic acid. The remainder of the lead 

 sulphide nitrate was allowed to evaporate over sulphuric acid. 

 The residue consisted of a mass of fine crystals radiating from 

 a centre. 1 



The crystals gave a very acid reaction when placed on moist- 

 ened blue litmus paper. They turned black and left a residue 

 when heated on platinum foil, and the residue was slowly 

 dissolved by nitric or hydrochloric acid. The quantity of resi- 

 due was very small, and no effervescence was observed. The 

 melting-point of the crystals was taken. A small quantity was 

 placed in a tube with thin walls, and gradually heated; at 

 150 C. the substance sublimed, leaving a white, cloudy stain 

 on the inner surface of the tube; at 190 C., this cloudy stain 

 changed to a pale green spot, and with increasing tempera- 

 ture to 210 C., no further change was noted. Dry sodium 

 carbonate was added to an aqueous solution of the crystals, 

 and a slight effervescence was observed. Some iron was sepa- 

 rated which possibly was in combination with the crystalline 

 principle. Negative results followed tests for formates, ace- 

 tates, malates, tartrates, citrates, phosphates, oxalates, alka- 

 loids, and glucosides. 



The amount of glucos^e present in the aqueous extract was 

 too small to determine quantitatively. Negative results for 

 tannin. 



Extract (4), the Yellow Base of the Leaf. 



The residual powder from the alcoholic maceration was 

 dried and replaced in the percolator. Cold distilled water was 

 allowed to percolate slowly through the powder. The aque- 

 ous extract was slightly acid in reaction. A known measure 



1 The material used in this analysis of the green part of the leaf was quite 

 dry and powdered readily. A previous examination of the fresh leaves gave 

 more satisfactory quantitative results. A gum was extracted which promises 

 to be of interest for a future study, and the crystals separated from the lead 

 sulphide filtrate are to be further investigated. 



