. PYKOKATECHIN AND SKATOL. 405 



4. Pyrokatechin = C 6 H 6 2 (metadihydroxylbenzol), is formed along with hydro- 

 chinon from phenol, and is an isomer of the former. It behaves like indol and 

 phenol, for when united with sulphonic acid, it yields the pyrokatechin-forming 

 substance. Small quantities sometimes occur in human urine ; it is more abundant 

 in the urine of children ; it becomes darker when the urine putrefies. 



5. Skatol, which is crystalline, and is formed during putrefaction in the intestine, 

 also appears in the urine as a compound of sulphonic acid (252). On feeding a 

 dog with skatol, Brieger found much potassic skatol-oxy -sulphate. 



Test. Skatol compounds are recognised by adding dilute nitric acid, which causes a violet 

 colour, or fuming nitric acid, which precipitates red flakes (Nencki). Its quantity is regu- 

 lated by the same conditions as indican. 



The aromatic oxyacids, hydroparacumaric acid, and paraoxyphenylacetic acid (the former a 

 putrefactive product of flesh, the latter obtained by,E. and H. Salkovvski from putrid albumin) 

 occur in the urine {Baumann, 252). Shake the urine treated with a mineral acid with ether, 

 evaporate the latter, and dissolve the residue in water. If aromatic oxyacids are present, they 

 give a red colour with Millon's reagent. 



Baumann gives the following series of bodies, which are formed from tyrosin by decomposi- 

 tion and oxidation ; most of the substances are formed both during the decomposition of 

 albumin, and also in the intestine, whence they pass into the urine: Tyrosin, C 9 H n N0 3 + H 2 

 = O 9 H 10 O 3 (hydroparacumaric acid) + NH 3 . C 9 H 10 O 3 = C 8 H ]0 O (paraethylphenol, not yet proved) 

 + C0 2 . C 8 H 10 O + 3 = C 8 H 8 3 (paraoxyphenylacetic acid) -f H o 0. C 8 H 8 3 = C 7 H 8 (parakresol) 

 + CO2. C 7 H 8 + 3 = C 7 H 6 3 (paroxybenzoic acid, not yet" proved) + H 2 0. C 7 H 6 = C 6 H 6 

 (phenol) + C0 2 . 



Potassium sulphocyanide, derived from the saliva, also occurs in urine. After acidulation 

 with hydrochloric acid, its presence may be detected by the ferric chloride test( 146 Gscheid- 

 len and J. Munk). One litre of human urine contains 0'02 to 0'08 gramme combined with an 

 alkali. 



Succinic acid (C 4 H 6 4 ) occurs chiefly after a diet of flesh and fat, and almost disappears after 

 a vegetable diet. It is a decomposition-product of asparagin, and occurs in considerable amount 

 in the urine after eating asparagus. It is also a product of the alcoholic fermentation ( 150), 

 and as it passes out of the body unchanged, it occurs in the urine of those who imbibe spirituous 

 liquors. It passes unchanged into the urine (Naubauer). 



Lactic acid (C 3 H 6 3 ) is a constant constituent of urine. Other observers have found ferment- 

 able lactic acid in diabetic urine ; sarcolactic acid after poisoning with phosphorus and in 

 trichinosis. Occasionally traces of volatile fatty acids are present. Some animal gum occurs 

 in urine (p. 384), and^Bechamp's ' ' nephrozymose " consists for the most part of gum {Land- 

 wehr). This substance is precipitated from urine by adding to it three times its volume of 

 90 per cent, alcohol. It is not a simple body, but at 60 to 70 C. it transforms starch into 

 sugar (v. Vintschgau). 



Ferments. Traces of diastatic, peptic, and rennet ferment have been found, especially in 

 urine of high specific gravity. Trypsin is said not to occur normally {Leo). 



Traces of sugar {Briicke, Bence Jones), to the amount of 0"05 to - 01 per cent., occur in 

 normal urine. After the ingestion of milk-, cane-, or grape-sugar (50 grms.) these varieties of 

 sugar appear in small quantity in the urine ( Worm-Mutter 267, 7). 



Kryptophanic acid (C 3 H 9 N0 5 ), according to Thudichum, occurs as a free acid in urine, but 

 Landwehr regards it as an animal gum. 



Aceton (C 3 H 6 0) is formed when normal urine is oxidised with potassic bichromate and sul- 

 phuric acid, and it is formed from a reducing substance present in normal urine (apparently 

 derived from the grape-sugar of the blood). Aceton occurs in traces as a normal urinary con- 

 stituent, which is increased during increased decomposition of the tissues, e.g., carcinoma, in- 

 anition. It has also been found in the blood in fever {v. Jacksch). Lieben's Test. Acidulate 

 half a litre of urine with HC1 and distil; when treated with tincture of iodine and ammonia 

 there is a turbidity due to iodoform. 



II. THE INORGANIC CONSTITUENTS OF THE URINE. The inorganic 

 constituents are either taken into the body as such with the food and pass off un- 

 changed in the urine, or they are formed in the body, owing to the sulphur and 

 phosphorus of the food being oxidised and the products uniting with bases to form 

 salts. The quantity of salts excreted daily in the urine is 9 to 25 grammes [J to 

 I oz.]. 



1. Sodic chloride to the amount of 12 (10 to 13) grammes [180 grains] is 

 excreted daily. It is increased, after a meal, by muscular exercise, drinking of 

 water, and generally, when the quantity of urine is increased, by the free use of 



