4 Dr, Thomas Thomson [July 



an intimate connexion between the depth of the colour and 

 the quantity emitted. When the urine is scanty it is al- 

 ways deeply coloured. Hence the reason of the red colour 

 of urine in fevers. When the quantity emitted is great the 

 colour is pale. I have seen it in cases of hysteria so nearly 

 colourless and tasteless, that it was only by concentration 

 I was able to satisfy myself that it contained the usual con- 

 stituents of urine. When such urine is concentrated it 

 gradually acquires the usual yellow colour of urine, and 

 this colour deepens into red when the concentration is 

 pushed far enough. Sometimes urine contains bile, and 

 then its colour is orange yellow. The presence of bile is 

 easily detected by pouring a little muriatic acid into the 

 urine suspected to contain it. If any be present the colour 

 immediately changes into green. 



Occasionally the colour of urine is so deep that it appears 

 almost black ; this is sometimes owing to a mixture of blood, 

 but sometimes it is produced by the substances taken into 

 the stomach. Thus, when preparations of iron are given at 

 the same time with rhubarb, the urine is said to assume a 

 blackish colour. Urine has frequently a red colour, and the 

 shade varies from rose red to scarlet. Red urine commonly 

 characterizes an inflammatory state of the system. Such 

 urine is always scanty. What the colouring matter is to 

 which it owes its particular tint has not been ascertained. 



Other colours of urine are mentioned by medical men ; 

 thus it has been described as greyish, greenish, and buff 

 coloured. Dr. Prout mentions a case in which it threw up 

 a cream like milk ; such urine might be called white, and 

 it doubtless owes its peculiar qualities to the presence of 

 chyle. 



The smell of urine is altered by various causes apparently 

 trifling. Asparagus gives it a peculiar fetid odour, while a 

 little oil of turpentine taken into the stomach, very soon 

 communicates to the urine the smell of violets. In many 

 individuals almost every article of food produces a corre- 

 sponding change on the odour of the urine. In the disease 

 called diabetes, the urine has a smell quite different from 

 that of common urine ; but not easily described ; I would 

 call it sweetish. 



The specific gravity of the lightest urine that ever came 



