114 PUBLIC HEALTH CHEMISTRY 



Fat. Soak in petroleum ether for several hours, pipette 

 off 20 c.c. of ether and evaporate off ether in a tarred vessel. 

 Averages n to 14 per cent (chicory 1 to 2 per cent). 



Sugar. Extract with hot water, invert, and estimate. 

 Under 1 per cent (chicory 10 to 18 per cent). 



Starch. Make a 10 per cent decoction, boil with animal 

 charcoal to decolorize (or acid permanganate), cool, and 

 test with iodine solution. Pure coffee contains almost no 

 starch, and the presence would indicate adulteration with 

 breadcrumbs, etc. Mounting in iodine (1 in 1000) brings 

 out the concentric rings. 



Detection of Chicory. 



Qualitative. Throw a pinch on to the surface of a glass 

 of water. Pure coffee remains floating on the top for 

 some minutes at least, whilst chicory sinks almost instantly, 

 and colours the liquid. The fragments which fall to the 

 bottom are taken out separately and examined by the 

 fingers (coffee is hard, chicory is soft). They are then 

 examined microscopically for the long testa cells of coffee 

 berry and the ladder-shaped structures, and in chicory for 

 the cells and dotted ducts. 



Quantitative. Take 10 grm. of sample in a boiling-flask, 

 add 100 c.c. of water, bring to the boil, and continue for 

 one half minute. Strain through muslin or a fine sieve, 

 and then through a filter-paper. Cool to 15-5 C. (6o F.) 

 and take specific gravity by bottle. Under these con- 

 ditions pure coffee gives a decoction having a sp. gr. rarely 

 exceeding 1009-5, and chicory about 1024 to 1025, or say 

 1024-5. Thus a difference of 15 per 1000 represents the 

 difference between 100 per cent coffee and 100 per cent 

 chicory, and from these data the amount of adulteration 

 can be calculated. Say that the sp. gr. of sample is 1014-5, 

 that is a rise of 5 ; therefore, as 15 : 5 : : 100 : 33-3 per cent 

 of chicory, and a fall of 10 from the sp. gr. of chicory, and 

 therefore as 15 : 10 : : 100 : 66-6 per cent of coffee. 



A second method is to take 10 grm., add 100 c.c, bring 

 to the boil, filter, boil dregs with another 150 c.c. for five 

 minutes, allow to settle, decant off clear liquid, mix with 

 previous filtrate, make up to 250 c.c. with aq. dest., mix 

 thoroughly, pipette off 50 c.c, evaporate to dryness in 

 weighed capsule over water-bath, weigh, and calculate 



