548 PHYSIOLOGICAL CHEMISTRY 



solution 1 and 20 c.c. of the alkaline tartrate solution. 1 Heat to boiling over an 

 asbestos gauze and boil gently for exactly three minutes. Let stand a moment that 

 the copper oxide may settle and then filter with suction through a Gooch crucible 

 with a heavy asbestos mat (or a calcium chloride tube with successive layers of 

 glass wool, coarse asbestos and fine asbestos wool) into a flask of about. 150 c.c. 

 capacity. Wash the residue in the flask twice by decantation with a little hot 

 water pouring the supernatant liquid through the filter. Throw away the clear 

 filtrate, rinse the flask and replace it. To the flask containing the cuprous oxide 

 add 5-20 c.c. of the acid ferric sulphate solution. 1 A green solution containing 

 ferrous sulphate is formed. Pour through the filter together with a little more of 

 the acid solution if necessary to completely dissolve the copper oxide. Wash flask 

 and filter with a little water. Titrate the filtrate with standard potassium per- 

 manganate solution 1 to a rose color. The procedure should be carried out as rapidly 

 as possible. 



Calculation. Multiply 'the number of cubic centimeters of permanganate used 

 by its copper equivalent as determined by standardization, and from the table 

 (page 546-547) obtain the corresponding value for the sugar under examination. 



Interpretation. See page 539. 



8. Fermentation Method. Principle. This method consists in 

 the measurement of the volume of carbon dioxide evolved when the 

 dextrose of the urine undergoes fermentation with yeast. None of 

 the various methods whose manipulation is based upon this principle 

 is absolutely accurate. The method in which Einhorn's saccharometer 

 (Fig. 5, page 30) is the apparatus employed is perhaps as satisfactory 

 as any for clinical purposes. 



Procedure. Place about 15 c.c. of urine in a mortar, add about i gram of 

 yeast (1/16 of the ordinary cake of compressed yeast) and carefully crush the 

 latter by means of a pestle. Transfer the mixture to the saccharometer, being 

 careful to note that the graduated tube is completely filled and that no air bubbles 

 gather at the top. Allow the apparatus to stand in a warm place (3OC.) for 12 

 hours and observe the percentage of dextrose as indicated by the graduated scale 

 of the instrument. Both the percentage of dextrose and the number of cubic 

 centimeters of carbon dioxide are indicated by the graduations on the side of the 

 saccharometer tube. 



The fermentation method becomes a much more accurate procedure 

 if the saccharometer of Lohnstein is used. 2 



1 (a) Copper Sulphate Solution. Forty grams of pure crystallized copper sulphate are 

 dissolved in water to make a liter. : . . 



(b) Alkaline Tartrate Solution. Dissolve 200 grams of Rochelle salts and 150 grams of 

 NaOH in water to make 1000 c.c. 



(c) Acid Ferric Sulphate Solution. Dissolve 50 grams of ferric sulphate in about 200 c.c. 

 of water and pour into this a mixture of 200 c.c. of concentrated sulphuric acid diluted 

 with about 400 c.c. of water. Mix and make up to 1000 c.c. 



(d) Potassium Permanganate Solution. Dissolve 5 grams of potassium permanganate in 

 water to make 1000 c.c. Standardization. Dissolve 0.250 gram of ammonium oxalate in 

 50-100 c.c. of water, add 1-2 c.c. of concentrated sulphuric acid and titrate with the per- 

 manganate to a rose color. About 22 c.c. will be required. Multiply the number of 

 grams of oxalate used by 0.895 to S et the equivalent in Cu of the number of cubic centi- 

 meters of permanganate u'setfT Calculate the Cu value of i c.c. 



2 Lohnstein: Munch, med. Woch., 1899, 1671. 



