PUS IN URINE. 29 



name of Trommer's test. It consists in adding to the urine 

 in a test tube a few drops of a solution of sulphate of copper, 

 so that the liquid shall assume a slightly blue tint. Aqua 

 potassse is then added in great excess (usually its quantity 

 should be equal to that of the urine) ; if sugar be present, a 

 precipitate is thrown down, which is re-dissolved as more 

 potassa is added, the liquid then assuming an azure blue 

 colour. On boiling the liquid, if sugar be present, a beauti- 

 ful yellow precipitate is thrown down, which contrasts very 

 remarkably with the blue solution. The precipitate consists 

 of sub-oxide of copper. In order to familiarise himself with 

 the reaction, the learner may make preliminary experi- 

 ments with a solution of honey, which contains grape 

 sugar. 



Pus sometimes occurs in urine. Urine containing it is 

 always slightly albuminous, and contains a sediment. The 

 sediment, when examined microscopically, contains the cells 

 which, when occurring in large quantities, are almost charac- 

 teristic of the secretion. They are precisely similar to the 

 colourless cells of the blood, and possess many nuclei, which 

 are brought out most distinctly by the addition of a little 

 acetic acid. 



Before leaving the chemistry of the urine, I must mention 

 that it is thus many medicinal substances and colouring mat- 

 ters, when taken internally, find their way out of the system. 



Chelidonium and rhubarb cause it to assume a yellow 

 colour. Oil of turpentine causes it to exhale an odour of 

 violets, and valerian and castoreum give it an odour of 

 myrrh. The mineral salts, when taken internally, also occur 

 in the urine, where they may be detected by suitable tests. 



