78 CHEMICAL PHYSIOLOGY. 



(6.) Evaporate a drop of distilled water to compare with 

 this no residue. 



(c.) Burn the stain of 1 (a.) in the flame : it chars, indicating 

 the presence of organic matter, while a faint trace of ash or 

 inorganic matter is left. 



2. The Quantity. Normal. About 2| pints (50 ounces), or 

 1500 cc., in twenty-four hours, although there may be a consider- 

 able variation even in health, the quantity being regulated by 

 the amount of fluid taken, and controlled by the state of the 

 tissues, the pulmonary and cutaneous excretions. 



Increased by drinking water ( Urina potus) or diuretics ; when 

 the skin is cool, its blood-vessels are contracted, and the cutaneous 

 secretion is less active ; after a paroxysm of hysteria, and some 

 convulsive nervous diseases; in Diabetes insipidus and D. mellitus; 

 some cases of hypertrophy of the left ventricle, and some kidney 

 diseases. The increase may be temporary or persistent, the 

 former as the effect of cold, diuretics, or nervous excitement ; the 

 latter in diabetes and certain forms of kidney disease. 



Diminished after profuse sweating, diarrhoea ; early stage of 

 acute Bright's disease ; some forms of Bright's disease ; the last 

 stages of all forms of Bright's disease ; in general dropsies ; in 

 acute febrile and inflammatory diseases. 



3. The Colour. Normal. Light straw to amber-coloured. The 

 colour varies greatly even in health, and is due to the presence 

 of pigments, probably largely derived from the decomposition of 

 haemoglobin. The colour largely depends on the degree of dilu- 

 tion of the urine pigments. 



Pale after copious drinking, in diabetes, anaemia, and chlorosis ; 

 after paroxysmal nervous attacks (hysteria). N.B. Pale urines 

 indicate the absence of fever. 



High-coloured after severe sweating, violent muscular exercise, 

 diarrhea, or during febrile conditions. 



Pathological pigments, purpurine or uro-erythrine in febrile 

 disorders ; bile pigments ; blood. 



Medicinal Substances. Creasote and carbolic acid make urine 

 nearly black. This is due not to carbolic acid, but to hydro- 

 chinon. Sometimes these urines become almost black on standing 

 exposed to the air. Rhubarb (gamboge-yellow) ; senna (brownish). 



4. The Specific Gravity. Normal. Specific gravity 1020 

 (1018-1025). 



