THE AROMATIC CONSTITUENTS OF THE UEINE. 267 



due treated with 3 or 4 c.c. of concentrated sulphuric acid, while still 

 warm. This solution is kept on the water-bath for five to ten min- 

 utes. It is then poured into 100 c.c. of water, the bottle is washed 

 out with a little more water, when the solution and washings are 

 filtered and titrated with the permanganate solution. The color at 

 first changes to green, and finally the solution becomes yellowish or 

 colorless. The calculation is conducted as outlined above. 



Skatoxyl Sulphate. Skatoxyl sulphate, like indoxyl sulphate, 

 occurs in the urine in combination with potassium and sodium. Its 

 amount, however, is normally small, and it may at times be absent 

 altogether. Larger quantities are found under pathological condi- 

 tions associated with an increased degree of intestinal putrefac- 

 tion, and it may then happen that more skatoxyl sulphate is found 

 than ipdican. This, however, is uncommon, and in disease also 

 more indican is usually present. Like indican, it is decomposed 

 on treating with concentrated hydrochloric acid, and on subsequent 

 oxidation the liberated skatoxyl yields pigments which are for the 

 most part of a red color. Of their chemical nature, however, 

 nothing is known. One of these may possibly be identical with 

 Rosin's urorosein. Rosin, to be sure, claims that the chromogen of 

 urorosein is not a conjugate sulphate but we know that a portion of 

 the skatol also appears in combination with glucuronic acid in the 

 urine, and it is hence possible that his pigment may be derived from 

 this source. Urines containing notable quantities of skatoxyl 

 become darker on exposure to the air, and may gradually turn a 

 reddish-violet or almost a black color. This change, as in the 

 phenol urines, begins at the surface and gradually extends down- 

 ward. 



Tests. To demonstrate the presence of skatoxyl in urine, this 

 is strongly acidified with hydrochloric acid and extracted with 

 amyl alcohol, which takes up the coloring-matter. Chloroform 

 and ether do not dissolve this in acid solution, but do so in neutral 

 or alkaline solution, providing that the pigment has been freshly 

 formed. 



Test for Urorosein (so-called). A few cubic centimeters of urine 

 are treated with an equal amount of concentrated hydrochloric acid 

 and one or two drops of a strong solution of calcium hypochlorite. 

 The indigo-blue is extracted with chloroform, and it will now be 

 observed that the supernatant fluid presents a red color. On shaking 

 with amyl alcohol this takes up the red pigment, which is thus 

 manifestly not identical with indigo-red. Upon the addition of 

 sodium hydrate to the alcoholic solution the color disappears, but 

 reappears upon the subsequent addition of hydrochloric acid. On 

 standing,, the color gradually disappears. Under normal conditions 

 this reaction is not well marked, but becomes quite distinct in cases 

 in which intestinal putrefaction is much increased. 



A portion of the skatol, as I have already stated, appears in the 

 urine as skatol-carbonic acid : 



