II. On the colouring and extractive matters of urine. -Part II

Abstract

Before entering on a consideration of the analytical details contained in the first part of this memoir, it will be necessary to determine the exact number of urinary extractive matters, the existence of which I am justified in assuming after having brought the examination of their composition to a close. Berzelius, as I have before stated, inferred from his experiments that human urine contained three distinct extractive matters, one soluble in absolute alcohol, another soluble only in alcohol of sp. gr. 0.833, and a third insoluble in alcohol of all strengths, and only soluble in water. A similar conclusion would probably be arrived at by any one perusing the account which I have given of my own experiments without at the same time possessing any information regarding the chemical nature of the com­pounds analyzed. Nevertheless this conclusion would be incorrect, since a few simple experiments suffice to prove that the extractive matter inso­luble in alcohol is not a distinct substance, but invariably contains a quan­tity of alkaline or earthy bases, on the removal of which the organic matter with which they were combined becomes soluble in alcohol, and that the extractive matters peculiar to urine are only two in number, the first being soluble in ether and alcohol, the Second soluble in alcohol only. This inference is quite consistent with the results derived from the analyses of the lead compounds obtained on various occasions from the extractive matter insoluble in alcohol, the details of which have been given in the first part of this memoir. A specimen of the extractive matter insoluble in alcohol was prepared in the following manner:—Ordinary urine was mixed with acetate of lead, and the precipitate thereby produced having been separated, basic acetate of lead was added to the liquid, and the second lead precipitate was filtered off, washed, and treated with dilute sulphuric acid. The excess of the latter was removed by means of carbonate of lead, and the filtered liquid was evaporated to a syrup, which was treated with alcohol. The latter left a portion of the syrup undissolved; and this portion, after being washed with alcohol, was again dissolved in water and sulphuretted hydrogen was passed through the solution, which, after being filtered from the precipitated sulphide of lead, was treated with peroxide of mercury and metallic mercury, for the purpose of removing the hydrochloric acid contained in it. After standing some time and being frequently agitated the liquid was filtered, and sulphuretted hydrogen was passed through it in order to precipitate the mercury in solution, and after being again filtered it was evaporated. The residue left on evaporation was dissolved in a little water, and the solu­tion was mixed with alcohol as long as any precipitate was produced; the precipitate collected at the bottom of the vessel forming a brown glutinous deposit, which, after pouring off the supernatant liquid, 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 slightly acid and nauseous taste. It was easily reduced by pounding to a light brown 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 small cavities or vesicles, caused doubtless by the escape of the water which it had absorbed from tho atmosphere. Its watery solution, which was of a dark yellowish-brown colour, had an acid reaction. Its external properties did not differ materially 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.”