ABNORMAL INGREDIENTS OF THE URINE. 



387 



Fig. 130. 



soluble impurities of the yeast, is poured off, and a small quantity of 

 the moist yeast-deposit at the bottom is added to the urine under exami- 

 nation. The mixture is then placed 

 in a ferment-apparatus and kept at a 

 temperature of about 25 (77 F.), for 

 forty-eight hours, when the gaseous 

 products of fermentation will have 

 been completely disengaged. The 

 most convenient form of apparatus is 

 a test-tube of known capacity (Fig. 

 -130, a, 6), supported by a foot and 

 provided with an India-rubber stopper, 

 through which passes a narrow glass 

 tube (c), open at both ends ; its inner 

 portion reaching to the bottom of the 

 test-tube, where it is bent upward, to 

 prevent the escape of gas, its outer 

 portion being bent downward, to allow 

 the liquid expelled to drop freely from 

 its orifice. The test-tube may be 

 graduated in cubic centimetres from 

 above downward. The apparatus 

 being filled with saccharine urine, 

 when fermentation begins the disen- 

 gaged gas rises in bubbles to the 

 upper part of the test-tube and col- 

 lects there, while the urine is forced 

 out through the bent glass tube. 

 Every cubic centimetre of carbonic 

 acid produced corresponds to 0.26 



milligrammes of sugar decomposed. A similar apparatus, containing 

 the same quantity of healthy urine and yeast, should be kept at the 

 same temperature for an equal time, as a comparative test; since a small 

 quantity of carbonic acid might be disengaged from the yeast itself, 

 owing to its imperfect purification. The difference between the two 

 cases is that in the yeast alone the disengagement of gas soon ceases ; 

 while in a saccharine solution the yeast-cells multiply indefinitely, and 

 carbonic acid continues to be produced until most of the sugar has been 

 decomposed. This method does not give the precise quantity of the 

 glucose contained in any single specimen, since some of the urine 

 escapes before its fermentation is fully completed ; but it is at the same 

 time the surest indication of the existence of sugar, and a ready means 

 of determining approximatively whether it be scanty or abundant in 

 amount. 



The simplest method of ascertaining the quantity of glucose in a 

 given specimen of urine with sufficient accuracy for all clinical pur- 



FERMENT-APPARATUS, contain- 

 ing saccharine urine in fermentation. a. 

 Upper part of the test-tube containing 

 carbonic acid. 6. Lower part of the test- 

 tube containing the fermenting liquid, c. 

 Bent glass tube, to allow the escape of 

 liquid, d. Liquid which has been forced 

 out from the test-tube by the accumula- 

 tion of gas. 



