detecting Adulterations in Coffee. 



105 



/ 



Uc 



in length, which terminates below in a narrow 

 tube (b c) I of an inch in diameter and 4 inches 

 in length ; the lower small opening (c) is closed by 

 means of a cork to a certain point, from which it is 

 graduated to tenths of a cubic centimetre : a number 

 of these tubes, with a suitable stand and a small 

 measure holding one cubic centimetre, complete the 

 apparatus. 



When it is to be used, the tube is closed below 

 and filled to within half an inch of the upper extre- 

 mity (a) with cold water (that has been boiled to 

 expel the gas and kept in a well-stoppered bottle to 

 prevent its reabsorption); a cubic centimetre of the 

 sample of ground coffee under examination is then 

 cautiously dropped on the surface of the water, 

 when we should notice (1) whether it sinks quickly 

 or slowly; (2) what tint and odour it imparts to 

 the water ; (3) the expansion in bulk as measured 

 in the graduated small tube ; (4) the change in colour 

 of the grounds, and whether they collect loosely or not. 



If it is good coffee and a pure article, it floats on the surface 

 for a considerable period, and if freshly roasted and ground will 

 often remain suspended for clays if the tubes are kept free from 

 agitation. In the majority of instances it falls in a few hours, 

 and imparts to the water in the large tube a delicate amber tint 

 and a faint coffee-like odour, each particle as it rests in the small 

 tube retaining its outline, individuality, and colour, and the in- 

 crease in bulk being about one-half a cubic centimetre. 



If it is chicory it sinks instantly, nearly the whole mass tum- 

 bling into the small tube in a single minute, and even in its 

 rapid passage through the water imparting to it a deep brown 

 colour, and an odour somewhat like that of liquorice. The tint 

 of the particles is at the same time altered greatly ; the expansion 

 of the mass is also very considerable, its bulk in a short time in- 

 creasing to nearly two and a half cubic centimetres ; and the 

 particles, losing their individuality, seem to fuse together and form 

 a mass almost without interstices. 



By preparing mixtures of chicory and coffee in different pro- 

 portions, we find that the first sinks rapidly, while the latter 

 remains suspended for a considerable period, though a small 

 portion may be carried down by the chicory in its sudden sub- 

 sidence. After a time (which may be shortened if desired, by 

 agitating the tube) the coffee sinks also ; and by noticing the 

 proportion of compact and loose sediment in the small tube, and 

 the position of the line of meeting of the dark- and light -coloured 

 solutions, we obtain an indication of the proportion of chicory to 



