188 THE URINE. 



of childhood it is not so dangerous, but with adults it 

 signals the approach of coma, of which it is, perhaps, the 

 cause, through lowering the alkalinity of the blood. Di- 

 acetic acid is a colorless, strongly-acid liquid, soluble in 

 water and ether. On heating it decomposes below 100 

 to acetone and carbon dioxid: 



CH 3 COCH 2 C0 2 H == CH 3 COCH 3 + C0 2 . 



With ferric chlorid it gives a violet-red solution, which 

 disappears on standing twenty-four hours and more quickly 

 upon boiling. This reaction can be used to detect diacetic 

 acid in the urine. A number of other substances like 

 salicylic and carbolic acids, antipyrin, and the acetates 

 give a somewhat similar reddish color. These are stable 

 at ordinary temperatures, and only that from the acetates 

 is decomposed by boiling. The test should be made upon 

 urine which has been comparatively freshly passed. 



393. Test fresh urine for diacetic acid by adding, 

 drop by drop, a solution of ferric chlorid as long as a 

 precipitate forms. This is ferric phosphate, formed from 

 the phosphates of the urine. Filter, and to the filtrate add 

 a few drops more of ferric chlorid. The diacetic acid gives 

 a violet-red color. Allow it to stand several hours, and 

 notice that it fades and disappears. 



394. If this violet-red color was obtained, boil an- 

 other portion of urine for five to ten minutes, and after 

 cooling repeat the test. If the red color was caused by 

 diacetic acid none will be obtained in this second test, since 

 the acid will have been decomposed by boiling. 



LACTOSURIA. 



Milk-sugar may be found in the urine of women 

 toward the end of pregnancy and a short time after child- 



