1867.] Extractive Matters of Urine. — Part II. 



127 



deposit, which, after pouring off the supernatant Uquid, was dissolved in 

 water. The solution on being evaporated over sulphuric acid left a residue, 

 consisting of what would be called the urinary extractive matter insoluble 

 in alcohol. It had the appearance of a dark brown, amorphous, brittle, 

 gum-like mass, opaque in thick layers, but translucent at the edges. It had 

 a shghtly acid and nauseous taste. It was easily reduced by pounding to 

 a light brov/n powder, and when exposed to the air it did not appear to 

 deliquesce ; but on being afterwards heated in the water-bath it swelled up 

 considerably and became filled with sm.all cavities or vesicles, caused 

 doubtless by the escape of the water which it had absorbed from tha 

 atmosphere. Its watery solution, which was of a dark yellowish-brown 

 colour, had an acid reaction. Its external properties did not differ mate- 

 rially from those ascribed to this substance by Berzelius, who says, "It has 

 a yellowish-brown colour, is opaque in the mass ; it has a slightly bitter taste, 

 remains dry in the air, and dissolves in water with a dark yellow colour." 



Now the substance as thus prepared was found to contain a considerable 

 quantity of bases, by combination with which the organic constituents were 

 rendered insoluble in alcohol. On being heated on platinum foil it swelled 

 up considerably, and gave off gaseous products having a smell like that of 

 burning bread, leaving at last a porous charcoal, which was with great diffi- 

 culty reduced to ash. The ash was greyish-brown and alkaline, but for 

 the most part insoluble in watey; it consisted of oxide of iron, alumina, 

 carbonate of lime, magnesia, carbonate of soda, and a trace of potash. A 

 quantitative determination of the ash yielded the following results : — 



0*7665 grm. of the substance heated for some time in the water-bath gave 

 0*1025 grm. ash =13*37 per cent. 



The finely powdered substance communicated no colour whatever to abso- 

 lute alcohol ; but on adding a few drops of concentrated sulphuric acid and 

 allowing to stand for some time, the liquid acquired a deep yellow colour, 

 exactly like that of solutions of the extractive matter soluble in alcohol. 

 The matter left undissolved by the acid mixture w^as, after pouring off the 

 liquid and washing with alcohol, treated with water, in which the greatest 

 part dissolved, but without communicating much colour to the liquid ; it 

 consisted of the sulphates of lime, magnesia, and other bases. This expe- 

 riment alone vv^ould suffice to prove that the substance contained the extrac- 

 tive matter soluble in alcohol in combination with various bases. A further 

 proof was afforded by another experiment. The watery solutions of the 

 urinary extractive matters become considerably darker on the addition 

 either of strong mineral acids, such as hydrochloric acid, or of alkalies. 

 The deepening of colour in the former case is due to decomposition, in the 

 latter to mere combination. Now on taking five equal measures of a watery 

 solution of the substance under examination, adding to the first merely 

 water, to the second acetic acid, to the third dilute hydrochloric acid, to 

 the fourth water and sufficient caustic potash to made it just alkaline, 

 and to the fifth strong hydrochloric acid, taking care that the bulk of 



