URINE. 131 



crystallizes out from the distillate. The crystals are soluble 

 in ether and melt at 72 C. 



CH 2 -COOH 

 DIACETIC ACID, | 



0=C-CH 3 



The urine must be tested soon after voiding, as this body 

 disappears upon standing. 



Strongly acidify some urine with H 2 S0 4 and shake it out 

 with ether. Separate the ether from the solution and shake- 

 out the former with water which is just colored with Fe 2 Cl 6 . 

 The watery solution becomes violet and upon the addition of 

 more Fe 2 Cl e turns bordeaux-red. 



The ferric chloride solution may also be added to the urine 

 directly. In this case the phosphates must be completely 

 removed by the Fe 2 Cl 6 and filtration. Then add more Fe 2 Cl 6 , 

 to the filtrate. 



Salicylic acid and salicylates give a similar reaction. 

 When these bodies are, present they may be removed from 

 the acidified urine by shaking it out with chloroform or ben- 

 zene in which the diacetic acid is not soluble. The urine is 

 then treated with ether as above. 



CH 3 

 ACETONE, | 



0=C- CH 3 



Distil 100 c.c. of urine to which has been added 2 c.c. of 

 50 per cent acetic acid. Take the first 50 c.c. of the distillate,, 

 add 1 c.c. of concentrated H 2 S0 4 diluted 8 times and redistil 

 over 25 c.c. Make the following tests with this solution: 



(a) Lieben's Test. Place some of the solution in a test- 

 tube and make it alkaline with sodium carbonate. Add 



