SUBSTITUTES AND ADULTERANTS. 2I9 



the analyst to at once deal with the whole class of pos- 

 sible adulterants, including many species of grain, while 

 the absence of more than traces of sugar in Roasted 

 coffee can likewise be turned to excellent account inas- 

 much as Chicory contains no starch, but is highly sac- 

 charine even after roasting, the percentage of sugar in 

 Roasted coffee ranging from o. o. to i. i, while in Roasted 

 chicory the quantity of sugar ranges from 12 to 18 per 

 cent. The proof of this character is best made by the 

 aid of the copper-reduction test, for which purpose a 

 standard solution of copper is required, which may be 

 prepared by dissolving 34.65 grams of crystalized sul- 

 phate of copper in 200 C. C. of water and adding to it 

 173 grams of double tartrate of potash and soda, with 

 400 C. C. of a solution of caustic soda, the whole being 

 subsequently diluted with water so as to occupy a litre. 

 The standard solution of copper made in this manner is 

 of such a strength that 10 C. C. are reduced by .050 

 grams of grape sugar, the best method of using this 

 solution being to take a known volume of it, say 10 C. 

 C. accurately measured out, and dilute it with three or 

 four times its volumeof boiling water and then dropping 

 into the boiling copper solution, w^hich is to be added, 

 until the point is just reached when the copper solution 

 is exhausted, and as the reduction of the copper-salt to 

 the state of red sub-oxide of copper progresses, the 

 precipitate will accumulate, and at the same time the blue 

 color will fade from the solution. The last delicate read- 

 ing is finally effected by half of the reduction between 

 the ferro-cyanide of potassium and copper solutions, for 

 which purpose a little of the liquid is filtered, acidified 

 shghtly with acetic acid and tested with a drop of the 

 solution of the ferro-cyanide of potassium. In this tri- 

 turate, as in all like cases, a rough and rapid estimation 



