502 PHYSIOLOGICAL CHEMISTRY 



TABLE II 



Log + Log + 



H H 



4.6 2SoXio~ 7 6.4 4.0 Xio~ 7 



4.8 i6oXio- 7 6.6 2.5 Xio~ 7 



5.0 iooXio~ 7 6.8 1.6 Xio~ 7 



5.2 63Xio~ 7 7.0 i.o Xicr 7 



5.4 4oXio~ 7 7.2 o.63Xio~ 7 



5.6 asXio" 7 7.4 o.4oXio~ 7 



5-8 i6Xio~ 7 7.6 o.2sXio- 7 



6.0 ioXio- 7 7.8 o.i6Xio- 7 



6.2 6.3Xio~ 7 8.0 o.ioXio- 7 



Interpretation. The H ion concentration of the urine is influenced 

 by the same factors as the titratable acidity (see page 499). The 

 normal values lie between 4.80 and 7.50 with a mean value of almost 

 exactly 6.00. For vegetarians the mean value is about 6.64. In 

 cardio-renal disorders the mean is 5.3. In most pathological conditions 

 the hydrogen ion concentration is increased. 



Determination of Hydrogen-Ion Concentration Using the Solutions of Clark 

 and Lubs. 1 The following indicators are suggested: thymol blue covering the 

 range of P//I.2 2.8; brom-phenol blue, 2.8 4.6; methyl red, 4.4 6.0; 

 brom-cresol purple, 5.2 6.8; brom-thymol blue, 6.0 7.6; phenol red, 

 6.8 - 8.4 ; cresol-red, 7.2 - &8 ; thymol blue, 8.0 - 9.6. Solutions of 0.04 

 per cent strength are used except for the phenol and cresol reds, which are used 

 in 0.02 per cent solution and the methyl red in 0.02 per cent solution hi 60 per 

 cent alcohol. 2 About 10 drops of each of these indicator solutions are added to 

 10 c.c. portions of standard buffer solutions and of unknown solutions hi test 

 tubes and the comparisons made. The following standard buffer solutions are 

 recommended : 3 



1 Clark: The Determination of Hydrogen-Ions, Baltimore, 1920. 



2 These indicators may be obtained, dry or in prepared solutions, from the LaMotte 

 Chemical Products Co. or Hynson, Westcott and Dunning, Baltimore, Maryland. Pre- 

 pared and standardized buffer solutions may also be obtained. 



3 The constituent solutions are prepared as follows: 



0.2 M potassium chloride. Dissolve 14.912 gm. in distilled water and make up to i 

 liter. The salt should be recrystallized and dried at about i2oC. for two days. 



0.2 M acid potassium phthalate. Dissolve 40.828 gm. in distilled water and make up 

 to i liter. The salt should be recrystallized from distilled water and dried at iio-ii5 

 C. for some hours. 



0.2 M acid potassium phosphate. Dissolve 27.232 gm. in distilled water and make up 

 to i liter. The salt should be recrystallized from distilled water and dried at iio-ii5 

 C. for some hours. 



0.2 M Boric Acid in 0.2 KCL Dissolve 12.4048 gm. of air dried boric acid and 14.912 

 gm. pure KC1 in distilled water and make up to i liter. 



o. 2 N Sodium Hydroxide. Dissolve 100 grams of the best NaOH in 100 c.c. of distilled 

 water in an Erlenmeyer flask (Pyrex). Cover the mouth of the flask with tin foil, and 

 allow the solution to stand overnight till the carbonate has settled. Cut a hardened 

 filter paper to fit a Buchner funnel. Treat it with warm, strong (i : i) NaOH solution. 

 Decant the soda and wash the paper first with absolute alcohol, then with dilute alcohol 

 and finally with targe quantities of distilled water. Place the paper on the Buchner funnel 

 and apply gentle suction until the greater part of the water has evaporated. Now pour 

 the concentrated alkali upon the middle of the paper, spread it with a glass rod, and filter 

 under suction. The clear solution is now diluted quickly with cold distilled water, that 

 has recently been boiled to remove CO 2 , to make approximately N NaOH (about 50 c.c. 

 per liter) . Ten c.c. of this is withdrawn and roughly standardized against N HC1. It is 

 then diluted till it is approximately 0.2 N with COr-free water and the solution poured 



