AND DIABETES 109 



laevo-rotation of a ray of polarized light, from which 

 of course must be deducted the dextro-rotation due 

 to any glucose which may be present. 



A fairly simple qualitative test is Stuart-Hart's : 

 Take 20 cc. of urine, add 20 cc. of water and a few 

 drops of acetic acid. Boil the mixture till the bulk 

 is reduced to about 10 cc. ; thus acetone and diacetic 

 acid are driven off. Add water to restore the bulk 

 to 20 cc. ; put 10 cc. into each of two test-tubes A 

 and B. To A add I cc. of hydrogen peroxide ; just 

 warm it, but do not boil, for one minute. Cool. 

 Add to A and B J cc. of glacial acetic acid, a few 

 drops of fresh sodium nitroprusside, and overlay with 

 2 cc. of ammonium hydrate. Stand four hours. If 

 /3-oxybutyric acid was present it will have been 

 oxidized to acetone, and a purple-red ring will form 

 where the fluids meet in A, but not in B. The 

 presence of sugar does not interfere with the reaction. 



The presence of acetone cannot be definitely 

 excluded without distilling the urine, but too delicate 

 tests are usually less valuable than more approximate 

 ones because, as in this instance, a trace may be 

 found normally. The presence of diacetic acid is of 

 more clinical importance. 



Tests for acetone in the urine : To 3 cc. of urine 

 add a few drops of fresh sodium nitroprusside (a 

 crystal in 5 cc. of water) . Cover with strong ammonia. 

 A magenta ring appears at the line of junction, and 

 spreads upwards (Jackson-Taylor). Or, to 5 cc. of 

 urine add \ cc. of 5 per cent sodium nitroprusside ; 

 make just alkaline with caustic soda, and acidify 

 with acetic acid. A reddish-violet colour develops. 



