1180 PHYSIOLOGY 



in a 100 c.c. beaker, add 5 c.c. acid sodium acetate solution and a few drops of cochi- 

 neal tincture. Heat the urine to boiling and run in slowly the standard uranium 

 acetate solution from a burette as long as a precipitate is formed. Again heat to 

 boiling and add the uranium solution drop by drop, until the red colour is changed to 

 green. This end-point can also be tested by taking out a drop and placing it in contact 

 with a drop of potassium ferrocyanide solution or on a little heap of this substance 

 finely powdered on a white piece of porcelain. A brown colour or precipitate is 

 formed when excess of soluble uranium salt is present in the solution. (A few more 

 drops may be required to reach this point than to turn the cochineal green.) 



The principle of the estimation of sulphates has already been described (p. 1163). 

 It is not advisable to attempt this volumetrically. 



