APPENDIX 465 



urine is reduced to 10 c.c. (originally 40 c.c.). Dilute this evaporated urine with an 

 equal amount of water, giving us 20 c.c. In each of two test-tubes put 10 c.c. of 

 this 20 c.c. To one tube add i c.c. of hydrogen peroxide and warm gently, without 

 boiling, for one minute; then cool. The other tube is left untreated. Next, to each 

 test-tube add 10 drops of glacial acetic acid and 5 to 10 drops of a freshly prepared 

 sodium nitroprusside solution and mix. Next carefully overlay each tube with 

 about 2 c.c. of concentrated ammonia. If 0-oxybutyric acid were present in the 

 tube treated with the hydrogen peroxide and thereby oxidized to acetone a violet- 

 red ring will develop at the point of contact while in the untreated tube there will 

 be no such color ring. 



A yellowish-brown ring from the presence of creatinin may show in the untreated 

 tube. It is well to allow the tubes to stand for three to four hours before finally 

 reporting the absence of /J-oxybutyric acid. It will probably show 0.2%. 



Acetone. To one-sixth of a test-tube of urine add a crystal of sodium nitro- 

 prusside. Make strongly alkaline with NaOH. Shake. The addition of a few 

 drops of glacial acetic gives a purple color to the foam, if acetone is present. 



Acetone is naturally present in exceedingly small quantity. It is very much 

 increased in advanced cases of diabetes mellitus. It is also frequently found in 

 scarlet fever, typhoid fever, pneumonia, nephritis, and severe anemias. It is often 

 present after ether or chloroform anaesthesia. 



Although the following test can be applied directly to the urine it is preferable 

 to obtain distillates when possible and test these. 



Gunning Test. To about 5 c.c. of the urine add a few drops of Lugol's solution 

 and then ammonium hydrate until a black precipitate forms. Allow to stand for 

 some time, when, if acetone is present, a yellowish precipitate of iodoform crystals 

 will separate. These should be identified by microscope. Iodoform crystallizes 

 in some modification of the hexagonal plate, usually a six-pointed stellate form. 

 If the crystals are not clearly defined, throw precipitate on filter, wash with a little 

 water, and pour over it a little hot alcohol. To this filtrate add water, drop by drop, 

 until a precipitate, which will consist of well-defined crystals of iodoform, is obtained. 

 Examine this by microscope. 



Never use an alcoholic solution of iodine in connection with this test. 



Diazo Reaction. To 5 c.c. sulphanilic acid solution (sulphanilic ac. i pt, HC1 

 50 pts., aq. 1000 pts.) add 2 drops of a 0.5% solution of sodium nitrate. Add an 

 equal quantity (5 c.c.) of urine. Shake and add quickly 2 or 3 c.c. of ammonium 

 hydrate. A carmine color, especially in the foam, shows a diazo reaction. If the 

 reaction is positive, and the mixture is allowed to stand for twenty-four hours, a 

 precipitate forms, the upper margin of which exhibits a green, greenish-black or 

 violet zone. 



Indican. Take 10 c.c. urine and treat it with i c.c. of sol. of lead subacetate. 

 Filter. Of this filtrate take 6 c.c. and treat with an equal amount of Obermayer's 

 reagent; allow to stand for five minutes then shake gently with 2 c.c. of chloroform. 

 Obermayer's reagent is strong HC1 containing 2 parts of ferric chloride to the liter 

 o.i gram to 50 c.c. of HC1. 



A more exact method is to pour off the supernatant acid urine. Wash the chlo- 

 roform with water, then pour off as much of the supernatant water as possible 

 and add 10 c.c. of alcohol. A clear blue fluid results. 

 30 



