BEVERAGES 129 



excess of acidity (over o-i per cent acetic) is also made 

 by consulting another table. (Bass, 1056). 



Saccharin. Treat dried extract with anhydrous ether ; 

 evaporate to dryness ; if residue sweet, infer presence of 

 saccharin. 



Preservatives. Boric acid: test ash (as on page 80). 

 Salicylic acid: kiln-dried malt contains a principle which 

 gives an identical reaction with ferric chloride. Hence 

 use Spica's test : Take 100 c.c. of beer, acidify with 

 H 2 SO 4 ; extract with ether ; separate ether ; evaporate 

 spontaneously ; and warm residue carefully with a drop 

 of strong HNO 3 . If salicylic acid is present, picric acid 

 is formed. Add AmOH or NaOH, and a bright-yellow 

 picrate is formed, which will stain a woollen thread 

 immersed in it. 



Arsenic. By Reinsch's test. Take 200 c.c. of sample, 

 add 30 c.c. strong HC1 and a piece of clean bright copper 

 foil \ in. x in. Boil for forty-five minutes, adding aq. 

 dest. to keep up bulk as required. Cool, and examine 

 copper foil. If clean and bright copper-coloured, As, Sb, 

 and Hg are absent. If changed, there may be A s or Sb 

 if deposit is black ; but if silvery, it is Hg. Wash gently 

 with water, alcohol, and ether in succession. Dry at 100 C. 

 Put in a perfectly dry 2-in. glass reduction tube, the upper 

 part of which has been previously warmed. Heat gently. 

 As, Sb, and Hg all sublime and condense in the upper part 

 of the tube as, respectively, As 2 O 3 (crystals) ; Sb 2 O 3 

 (amorphous) ; and Hg (globules). Examine sublimate 

 magnified 200 times. Arsenic gives octahedral crystals. 

 Antimony gives an amorphous mass. Mercury gives 

 globules. If arsenic found, wash out sublimate with 

 weak KOH solution and put two portions on a white slab : 

 (i) Touch one with ammonia-cupric solution, when 

 Scheele's green is formed ; (2) Touch other with ammonia- 

 silver-nitrate solution canary-yellow precipitate. If 

 antimony found, wash out with weak tartaric acid, which 

 forms tartrated antimony. Add HC1 and H 2 S orange 

 precipitate. If mercury found, expose to iodine vapour 

 yellow iodide formed. A control should be done with the 

 distilled water and the HC1 and copper foil. 



Marsh's and Gutzeit's tests are also used. 



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