XXIII.] QUANTITATIVE ESTIMATION OF SUGAR. 145 



(b.) Dip the tube in cold water to cool it. The volume must be exactly 4 

 drachms. If it is less, add water ; if more, evaporate it. If the colour of the 

 boiled liquid is the same as that of the ferric acetate -grain standard, or 

 paler, the urine contains i grain of sugar per fluid ounce, or less. 



(c.) Should the colour be darker than the standard, place some of the boiled 

 liquid in the graduated stoppered tube (fig. 72) to fill ten divisions of the 

 scale, while the stoppered tube affixed to the former is filled with the SS. of 

 ferric acetate. Fill up the graduated tube with distilled water until the dark 

 red liquid has the same colour as that of the SS. These tints are best compared 

 in the flat-bottomed tubes supplied with the apparatus. 



(d. ) Read off the level of the fluid in the saccharimeter, each division 

 above 10 = 0. i grain per fluid oz. Thus, 13 divisions = .3 grains per fluid oz. 



(e.) If more than 8 grains per oz. are present, further dilution is required. 

 Full instructions are supplied with the apparatus. 



4. Fermentation Method. Sir William Roberts has devised a method 

 depending on the diminution of the specific gravity which the fluid undergoes 

 during fermentation. Every degree lost in the sp. gr. corresponds to I 

 grain of sugar in a fluid ounce. Recently a modification of this method has 

 been introduced in Germany under the title of Einhorn's Fermentation 

 Saccharometer (fig. 73). Estimate the specific gravity of the urine, which is 

 diluted according to the specific gravity as follows. If the urine have a 



Sp. gr. 1018-1022, dilute it with 2 vols. water. 

 1022-1028, 5 

 1028-1038, 10 



Measure 10 cc. of the urine, and, by means of a pipette, place it in the appa- 

 ratus. Add i gram of yeast to the urine in the tube, incline the latter until 

 the fluid flows into the limb of the latter. Let 

 the apparatus stand at the ordinary temperature 

 for fifteen hours, and then the quantity of C0 2 

 given off is read off. The scale on the tube is 

 empirical, and indicates directly the percentage of 

 sugar in the urine. 



5. Acme Sacchar-Ureameter (fig. 74). This is 

 a simple apparatus for the direct estimation of sugar 

 and urea in urine ; the former by the fermentation 

 test, the latter by the hypobromite. 



Estimation of Sugar. Measure i volume of the 

 urine in the tube so marked, and pour it into the 

 bottle a. Wash out with water, and add to the 

 urine. Dilute further with water if the urine 

 contains much sugar. Acidify the urine with 

 tartaric acid until acid to test-paper (f-i per cent, 

 of free acid). Add a few grains of yeast, and 

 connect up the apparatus. The measuring-tube b 

 is filled to zero with a saturated solution of common 

 salt (the CO,, is soluble in water). When b is 

 full, c must "be empty. Place the whole in a 



moderately warm place the surrounding temperature should be such as to 

 enable it to rise to 92-94 F. When the fermentation . ceases or from time 

 to time during the time of fermentation lower c until the levels of brine are 

 equal. Allow it to cool, and read off the result 



FIG. 73. Einhorn's Fermen- 

 tation Saccharometer. 



