BXCRETION BY THE KIDNEY. 



419 



URINE CONSIDERED PHYSICALLY AND CHEMI- 

 CALLY. 



Urine is naturally a iluid of very Yariable composition, espe- 

 cially regarded quantitatively— a fact to be borne in mind in 

 considering all statements of the constitution of this fluid. 



Specific Gravity. — ^Urine must needs be heavier than water, 

 on account of the large variety of solids it contains. The aver- 

 age specific gravity of the urine for the twenty-four hours is in 

 maiJ 1015 to 1030 ; in the horse, 1030 to 1060 ; in the ox, 1020 

 to 1030; in the sheep and goat, 1005 to 1015 ; in the pig, 1010 to*^ 

 1015 ; in the dog, 1030 to 1050. It is lowest in the morning and 

 varies greatly with the quantity and kind of food eaten, the ac- 

 tivity of the lungs and especially of the skin, etc. 



Color — Some shade of yellow, which is also very variable, 

 being increased in depth either by the presence of an excess of 

 pigment or a diminution of water. In herbivora the urine is 

 turbid, and may darken on exposure to the air. 



The reaction of human urine is acid, owing to acid salts, 

 especially acid sodium phosphate (NaHjPO,). In the carnivora it 

 is strongly acid ; in the herbivora, alkaline. The reaction of urine 

 depends largely though not wholly on the character of the food. 



Quantity. — This is, of course, like the specific gravity, highly 

 variable, and frequently they run parallel with each other. 



The following tabular statement will prove useful for refer- 

 ence: 



Composition of the Urine (BoussingauU). 



Urea 



Potas^um hippurate 



All^line lactates. , : 



Potassium bicarbpnate 



Magpesium carbonate 



Calraum oarlyDnate 



Potassium sulphate 



Sodium chloride 



Silica 



Phosphates 



Water and substances undetermined, 



Total 



Pig4 



4-9 

 0-0 



10-7 

 0-9 



trace. 

 2-0 

 1-3 

 0-1 

 1-0 



979-1 



1000-0 



* Diet of clover, grass, and oats. 

 t Diet of potatoes, cooked. 



f Diet of hay and potatoes. 



