REAGENTS AND SOLUTIONS 635 



Furfural Solution. 1 Add i c.c. of furfural to 1000 c.c. of distilled 

 water. 



Fusion Mixture. Two parts of sodium carbonate to one part of 

 potassium nitrate. 



Guaiac Solution. 2 Dissolve 0.5 gram of guaiac resin in 30 c.c. of 

 95 per cent alcohol. 



Giinzberg's Reagent. 3 Dissolve 2 grams of phloroglucinol and i 

 gram of vanillin in 100 c.c. of 95 per cent alcohol. 



Haines* Solution. 4 This solution may be prepared by dissolving 

 8.314 grams of copper sulphate in 400 c.c. of water adding 40 c.c. of 

 glycerol and 500 c.c. of 5 per cent potassium hydroxide solution. 



Hayem's Solution. This solution has the following formula: 



Mercuric chloride o. 25 gram. 



Sodium chloride 0.5 gram. 



Sodium sulphate 2.5 grams. 



Distilled water ^ 100 . o grams. 



Hopkin's-Cole Reagent. 5 To i liter of a saturated solution of 

 oxalic acid add 60 grams of sodium amalgam and allow the mixture 

 to stand until the evolution of gas ceases. Filter and dilute with 2-3 

 volumes of water. 



Hopkin's-Cole Reagent (Benedict's Modification). Ten grams 

 of powdered magnesium are placed in a large Erlenmeyer flask and. 

 shaken up with enough distilled water to liberally cover the magnesium. 

 Two hundred and fifty c.c. of a cold, saturated solution of oxalic acid is 

 now added slowly. The reaction proceeds very rapidly and with the 

 liberation of much heat, so that the flask should be cooled under running 

 water during the addition of the acid. The contents of the flask are 

 shaken after the addition of the last portion of the acid and then poured 

 upon a filter, to remove the insoluble magnesium oxalate. A little 

 wash water is poured through the filter, the filtrate acidified with 

 acetic acid to prevent the partial precipitation of the magnesium on long 

 standing, and made up to a liter with distilled water. This solution 

 contains only the magnesium salt of glyoxylic acid. 



Hypobromite Solution. 6 The ingredients of this solution should 

 be prepared in the form of two separate solutions which may be united 

 as needed. 



1 Mylius's modification of Pettenkofer's test, pp. 211 and 449; v. Udr&nsky's test, pp. 

 211 and 449. 



2 Guaiac test, pp. 15, 265, and 447. 



3 Test for free acid, p. 156. 



4 Haines' test, p. 436. 



5 Hopkins-Cole reaction, p. 98. 



6 Used for determination of urea. 



