FOODS 101 



prevent a growth of fungus. It is detected by soaking in a 

 solution of K 4 FeCy 6 , acidulated with acetic, when a purplish 

 or reddish-brown coloration indicates the presence of copper. 



Ergot in Flour. (i) Microscope ; (2) Place some 

 flour in a test tube, and a few c.c. 10 per cent KOH, and 

 warm gently : smell of propylamine (like warm urinous 

 napkin) ; (3) Shake up 2 grm. of flour with 10 c.c. of 

 alcohol (70 per cent) containing i /2 c.c. HC1. On standing, 

 a red colour slowly forms. 



Baking-Powders. Definition : " A baking-powder may 

 be defined as a salt or mixture of salts with or without a 

 diluent such as starch, which evolves carbon dioxide when 

 moistened, and on heating " (Moor). The Sale of Food and 

 Drugs Act, 1899, enables authorities to take cognizance 

 of the constitution of a baking-powder as an article which 

 " ordinarily enters into or is used in the composition or 

 preparation of human food." 



The best mixture is one containing the proper chemical 

 proportions of good cream of tartar (KHC 4 H 4 O 6 ) and 

 baking soda (NaHCO 3 ), with a filling of about 20 per cent 

 of pure starch. The chemical action forms rochelle salt 

 (KNaC 4 H 4 O 6 ). This keeps well, reacts slowly and in a 

 definite way ; and the rochelle salt formed has a very 

 weak retarding action on ferments, and so does not disturb 

 the digestive processes. 



Alum is objectionable from inhibiting the digestive 

 ferments, precipitating the phosphoric acid and phosphates, 

 and liberating sulphate of soda, which is purgative. 

 Bisulphate of potash also liberates the last-named salt. 



Tartaric acid and acid phosphate of lime liberate the CO 2 

 too quickly. 



Ammonium carbonate and superphosphate of lime (free 

 from sulphate) are not objectionable. 



Available carbon dioxide should be at least 8 per cent 

 by weight. 

 KHC 4 H 4 O 6 + NaHCO 3 = KNaC 4 H 4 O 6 + H 2 O + CO 2 . 



Numerous prosecutions for the presence of alum have 

 been made. 



STARCHES. 



Take a clean slide, and put on it a small drop of water. 

 With a platinum loop, transfer a portion of the starch 



