736 PHYSIOLOGICAL CHEMISTRY. 



to which the glycuronic acid is linked. The amount usually present 

 is not sufficient to reduce Fehling's solution, unless the boiling is con- 

 tinued for a long time. The conjugate glycuronates are Isevorotatory. 



Glycuronic acid reduces Fehling's and bismuth solutions, forms an osazone 

 melting at 115 C. (239 F.), does not ferment with yeast, and is dextrorotatory. 

 5 c.c. of urine containing glycuronic acid when decolorized with boneblack, 

 mixed with an equal volume of hydrochloric acid and 0.025 phloroglucin, de- 

 velops a deep-red color on heating. (This reaction is also shown by pentoses ; 

 glycilronic acid does not give the orcin reaction.) 



Acetone, diacetic and /3-oxy-butyric acids. These substances, 

 commonly called the " acetone bodies/' are believed to be due to an 

 abnormal metabolism of fat, though the protein metabolism may also 

 be concerned. As can be seen from the following reactions acetone 

 is derived from diacetic acid, and diacetic acid from /9-oxy -butyric 

 acid : 



CH 3 CH(OH).CH 2 .COOH + O = CH 3 .CO.CH 2 COOH + H 2 O 

 /3-oxy-butyric acid. Diacetic acid. 



CH 3 .CO.CH 3 .COOH = CH 3 .CO.CH 3 -f CO 2 

 Acetone. 



As oxy-butyric acid and diacetic acid are unstable, acetone is the 

 first of these bodies to appear in the urine, and it is only as the 

 pathological conditions increase that diacetic and finally oxy-butyric 

 acid are found. Acetone is, indeed, normally present in minute 

 amounts, and is always increased in the presence of the other two. 

 As these bodies have the same origin, their presence has the same sig- 

 nificance, the higher members showing merely a graver aspect. 



They are increased, in many conditions : with a carbohydrate-free 

 diet, in any cachectic condition, in many types of fever. They are 

 markedly increased in diabetes. 



The more severe cases of acetonuria are also referred to as acido- 

 sis (acid intoxication). The term emphasizes, of course, not the acid 

 excreted in the urine, but the acid remaining in the system. In 

 order to neutralize this abnormal acidity without using the fixed 

 alkali of the body the organism converts less nitrogen into urea 

 than is normally done, and uses it as an alkali in the form of ammonia. 

 Thus the proportion of the urinary nitrogen in the form of ammonia 

 is increased in acidosis, becoming even 40 per cent., the normal being 

 5 or 6 per cent. This percentage is the best index of the severity of 

 the condition. 



Acidosis is most common in diabetes and pernicious vomiting of 

 pregnancy, and indicates the danger of coma. 



