igS Veterinary Medicine. 



diuresis. It may be 1050 to 1060 in glycosuria. Undissolved 

 solids that are merely suspended in the urine do not affect its 

 density. 



A rough estimate of solids may be made by multiplying the 

 last two figures of a specfic gravity expressed in four figures by 

 2.33. The result approximates to the number of grammes of 

 solids in 1000 cc. 



Chemical Reaction of Urine. The liquid is tested by litmus 

 paper, red and blue, weakly impregnated. The normal reaction 

 is determined by the food : the urine of carnivora and sucking 

 . herbivora is acid turning blue litmus red : the urine of vege- 

 table feeders is alkaline turning reds blue. In the horse the 

 alkalinity is mainly due to excess of lime bicarbonate, passing, 

 with standing, into lime carbonate, the carbon dioxide being de- 

 rived from organic acids (lactic, malic, citric, etc.), by oxidation. 

 The hippurates are also alkaline in reaction. In dogs the acidity 

 is due to lime and soda phosphates, sulphates, urates and oxalates. 



Pathologically we find the urine strongly alkaline from the 

 evolution of ammonia from urea, in fermentations occurring with 

 prolonged retention in the bladder or in cystitis. The urine 

 is acid even in herbivora in all fevers in which appetite is lost or 

 seriously impaired, and which the metabolism is excessive. 



Chemical Changes in the Urine in Disease. Sodium 

 Chloride, is present in large amount in health (horse 25 to 35 

 grammes, dog 0.25 to 5 grammes daily) is diminished in fever, 

 anaemia, visceral and exudative inflammations. It is increased 

 during the absorption of false membranes and exudates. It is 

 thrown down by adding solution of nitrate of silver, the curdy 

 white precipitate being insoluble in nitric acid. 



Phosphates of lime, soda, potash and, scantily, of mag- 

 nesia are normally present (horse 0.08 to 0.60 gramme phos- 

 phoric acid daily) and are present in excess in digestive disorders 

 and in malnutrition of bones (rachitis, osteoporosis and rheuma- 

 toid arthritis). The alkaline phosphates are very soluble and 

 never precipitated. Earthy phosphates dissolve in acid urine, 

 but are precipitated from alkaline. To a little of the urine add a 

 few drops of acetic acid, followed by a few drops of uranium 

 acetate. A yellow precipitate of uranium and ammonium double 

 phosphate is thrown down. 



