preface to fifteenth edition

PRACTICAL LABORATORY INFORMATION 11.111
Bang’s reagent (for glucose estimation): dissolve 100 g of K 2 CO 3 , 66 g of KCl, and 160 of
KHCO 3 in the order given in about 700 mL of water at 30C. Add 4.4 g of copper sulfate and
dilute to 1 liter after the CO 2 is evolved. This solution should be shaken only in such a manner
as not to allow the entry of air. After 24 hours 300 mL diluted to a liter with saturated KCl
solution, shaken gently and used after 24 hours; 50 mL # 10 mg glucose.
Barfoed’s reagent (test for glucose): dissolve 66 g of cupric acetate and 10 mL of glacial acetic
acid in water and dilute to 1 liter.
Barium chloride, BaCl 2· 2H2O90.5N: 61gper liter.
Barium hydroxide,
Barium nitrate,
Ba(OH) · 8H O90.2N: 32g
2 2
Ba(NO ) 90.5N: 65g
3 2
per liter.
per liter for saturation.
Baudisch’s reagent: see cupferron.
Benedict’s qualitative reagent (for glucose): dissolve 173 g of sodiumcitrate and 100 g of
anhydrous sodiumcarbonate in about 600 mL of water, and dilute to 850 mL; dissolve 17.3 g
of CuSO 4· 5H2O in 100 mL of water and dilute to 150 mL; this solution is added to the citratecarbonate
solution with constant stirring. See also the quantitative reagent below.
Benedict’s quantitative reagent (sugar in urine): This solution contains 18 g copper sulfate,
100 g of anhydrous sodiumcarbonate, 200 g of potassiumcitrate, 125 g of potassiumthiocyanate,
and 0.25 g of potassiumferrocyanide per liter; 1 mL of this solution # 0.002 g sugar.
Benzidine hydrochloride solution (for sulfate determination): mix 6.7 g of benzidine
[C 12 H 8 (NH 2 ) 2 ] or 8.0 g of the hydrochloride [C12H 8(NH 2) 2 · 2HCl] into a paste with 20 mL of
water; add 20 mL of HCl (sp. gr. 1.12) and dilute the mixture to 1 liter with water; each mL of
this solution is equivalent to 0.00357 g H 2 SO 4 .
Benzopurpurine 4B (indicator): dissolve 0.1 g in 100 mL water; pH range blue-violet 1.3–4.0
red.
Benzoyl auramine (indicator): dissolve 0.25 g in 100 mL methyl alcohol; pH range violet 5.0–
5.6 pale yellow. Since this compound is not stable in aqueous solution, hydrolyzing slowly in
neutral medium, more rapidly in alkaline, and still more rapidly in acid solution, the indicator
should not be added until one is ready to titrate. The acid quinoid formof the compound is
dichroic, showing a red-violet in thick layers and blue in thin. At a pH of 5.4 the indicator appears
a neutral gray color by daylight or a pale red under tungsten light. The change to yellow is easily
recognized in either case. Cf. Scanlan and Reid, Ind. Eng. Chem., Anal. Ed. 7:125 (1935).
Bertrand’s reagents (glucose estimation): (a) 40 g of copper sulfate diluted to 1 liter; (b) rochelle
salt 200 g, NaOH 150 g, and sufficient water to make 1 liter; (c) ferric sulfate 50 g, H 2 SO 4
200 g, and sufficient water to make 1 liter; (d) KMnO 4 5 g and sufficient water to make 1 liter.
Bial’s reagent (for pentoses): dissolve 1 g of orcinol in 500 mL of 30% HCl to which 30 drops
of a 10% ferric chloride solution have been added.
Bismuth chloride, BiCl390.5N: 52 g per liter, using 1:5 HCl in place of water.
Bismuth nitrate, Bi(NO) ·5HO90.25N: 40 g per liter, using 1:5 HNO in place of water.
2 3 3 2 3
Bismuth standard solution (quantitative color test for Bi): dissolve 1gof bismuth in a mixture
of 3 mL of concentrated HNO 3 and 2.8 mL of H 2 O and make up to 100 mL with glycerol. Also
dissolve 5 g of KI in 5 mL of water and make up to 100 mL with glycerol. The two solutions
are used together in the colorimetric estimation of Bi.
Boutron-Boudet solution: see soap solution.