183 



CLINICAL DIAGNOSTICS. 



Fig. 41. 



e. Grape sugar, Glycosuria, by means ordi- 

 naril}- employed can be detect- 

 ed in urine in disease only, viz. 

 in diabetes mellitus. In horses 

 this disease has been observed in a few- 

 instances only, in dogs it is common. We 

 suspect the presence of sugar in polyuria 

 when the specific gravity of the urine is 

 high. 



Chemical determination. If albumin is 

 present this must first be removed by adding 

 acetic acid, boiling, and filtering. Then add 

 to 10 cc urine 1 cc caustic potash solution; if 

 this produces cloudiness, filter again. Then 

 add about 3 drops of a 10% solution of sul- 

 phate of copper. The appearance of a light 

 blue color is in itself an indication of grape 

 sugar; now heat the fluid, if grape sugar is 

 present an orange yellow precipitate which 

 gradually extends downward is formed at the 

 surface; this is an oxide of copper. 



This test (Trommer's test) 



is by no means reliable for horse 



urine because the latter contains other bodies that have a 



reducing power: Pyrocatcchiii, etc. On the other hand, 



substances that prevent the reduction (or precipitation) of 



oxide of copper may be present. Pure grape sugar, when 



added to horse urine, can sometimes not be detected at all 



by means of Trommer's test. In all cases of doubt we must 



therefore resort to the fermentation test, as follows : 



Boil 20 cc of urine that has been freed from albumin, let cool 

 and add a piece of baker's j^east as large as a pea, shake thorough- 

 ly, pour into a fermentation tube and close the latter with metallic 

 mercury. Keep the tube at room temperature for 24-48 hours. If 

 sugar is present fermentation will set in and the C0„ thus pro- 

 duced will collect in the top of the tube where the percentage is 

 indicated by a graduated scale. 



Ce Hi2 Oe = 2C., H, OH., -f C C, 

 Grape sugar = alcohi 1 + carbondioxide. 



This test can of course be relied upon only when we 



Fermentation tube. 



