CHEMISTRY, 



113 



< in Coffee. Professor John 0. 



York, has contrived nil appara- 



i adulterations in colfec. It is n I ube 



in diameter anil cijht inches long, 



!.>\v in a narrow tube one 



:in inch in diameter and four inches 



lower small opening is closed by 



n eojk to a cenain point, from which 



-radiiated to tenths (1 f a cubic centimetre. 



When tli" tube is to li- used, it is closed below 



\iled to within half an inch of the upper 



,:iity with cold water (previously boiled 



,;>el tin. 1 air"). A cubic centimetre of the 



Iti f ground coffee, under examination, is 



then dropped <>n the surface of the water. If 



offeo and a pure article, it floats on 

 irt'aco for a considerable period, and if 

 . roasted and ground will often remain 



-uspcnded, if the tube is kept free 

 from agitation. In the majority of instances 

 the coilVe falN in a few hours, and imparts to 

 the water in the large tube a delicate amber 

 tint and a faint coffee-like odor ; each particle 

 as it rosts in the sma 1 .! tube retaining its out- 

 line, individuality and color, and the increase 

 in bulk of the whole being about one-half a 

 cubic centimetre. If the article is chicory, it 

 sinks instantly, nearly the whole mass turn- 

 into the small tube, in a minute, and in its 

 rapid passage through the water imparts to it 

 a deep-brown color and an odor like that of 

 liiniorici-. The tint of the particles is at the same 

 time altered greatly; the bulk increases to 



and a half cubic centimetres; and 

 the particles, losing their individuality, seem to 



iref her and form a mass almost without 

 interstices. In testing mixtures of chicory and 

 coffee in different proportions it is found that 

 tho lirst sinks rapidly, while the latter remains 

 suspended for some time, though a small por- 

 tion may be carried down by the chicory in its 

 sudden subsidence. Presently the coffee sinks 

 also ; and by noticing tho proportion of com- 

 pact and of loose sediment in the small tube, 

 and tho position of the line of meeting of the 

 dark and light-colored solutions, an indication 

 can bo obtained of the proportion of the chicory 

 to the coffee, which coincides very nearly with 

 that employed in making the mixture. The 

 tint of the fluid in the large tube and tho in- 

 in tho bulk of the solid matter are also 

 of use in arriving at a 'correct estimate. Old 

 coffee-grounds, wheat, etc., also subside rapidly 

 with the chicory, and collect in tho small tube. 



s or beans are present, they may bo easily 



distinguished under microscopic examination, 



peculiarities of the starch-cells of each ; 



and such examinations are greatly facilitated 



by the use of the tube, for when the subsidence 



!]>Icte, it only remains to remove the cork 

 gently from the small tube, and allow a little of 

 tho lower portion of the sediment, which con- 



t ho foreign matters, to escape into a shal- 

 low dish, whence particles may bo transferred 

 microscopic slide; and in this way layer 

 after layer of the deposit may be examined. 

 VOL. vii. 8 



The Akazga Potion. Dr. Thoman R. Fraser 



h:i- subjected to a cli.-lnicnl examination the 



celebrated akazga poison, the admim-- 

 of which is the ordeal for tho detection of 

 crimes and witchcraft adopted by some of th- 

 tribes on the West coast of Africa, alluded to 

 in the writings of M. du Chaillu and Winwood 

 Reade. The akazga is a tree the bark and leave* 

 of which yield the drug. By boiling the pow- 

 dered bark with alcohol of 85. per cent, and 

 distilling and evaporating the tincture, a brown 

 shining extract is obtained, weighing from 12 

 to 15 per cent, of the bark employed. It has a 

 bitter non-persistent taste, and when treated 

 with concentrated sulphuric acid produces a 

 brownish-yellow color, which is not materially 

 affected by heat nor by solution of protochlo- 

 ride of tin. This extract is treated with a very 

 dilute solution of tartaric acid which removes 

 77 per cent., and is filtered. The clear yellow- 

 ish-brown acid solution is shaken with succes- 

 sive portions of ether so long as any color is 

 removed; and by this means also a small 

 quantity of an aromatic oil is separated from 

 it. After decantation, a solution of carbonate 

 of sodium is added to the liquor, so long as it 

 causes a nearly colorless, flocculent precipitate. 

 It is again shaken with ether, which is decanted, 

 and agitated with three successive portions of 

 distilled water, and finally received in a bottle 

 containing a dilute solution "jpf tortaric acid, 

 and shaken with it. The tartaric solution is 

 afterward exposed to a gentle heat to free it 

 completely from ether filtered, and again 

 treated with carbonate of sodium, by means 

 of which a bulky, colorless, and flocculent pre- 

 cipitate is obtained. This is collected in a 

 filter, washed, and dried, by exposure to a gen- 

 tle heat for a short time, and then by tho ac- 

 tion of sulphuric acid in vacuo. By this 

 means a colorless, amorphous substance is ob- 

 tained, which is the active principle of the 

 akazga poison, and which possesses the general 

 properties of a vegetable alkaloid. About ten 

 grains may be separated from 500 grains of the 

 powered stem-bark, or 2 per cent. "When 

 heated the substance becomes yellow, then melts, 

 and gives off fumes of a pungent, disagreeable 

 odor, and finally becomes charred, but leaves 

 almost no residue if the heat be continued for 

 a sufficient time. Its solutions have an alkaline 

 reaction, and neutralize acids; and the salts 

 are freely soluble in water, and have a very 

 bitter, non-persistent taste. Concentrated ni- 

 tric, hydrochloric, and sulphuric acids change 

 its color to brown, but these in a diluted state, 

 as well as many of the organic acids, form with 

 it pale-yellowish solutions. 



The alcoholic extract of akazga possesses 

 physiological properties very similarjto those 

 of mix vomica ; and comparative experiments 

 were detailed, to show that the alkarokl of 

 akazga has exactly tho same actions as tho ex- 

 tract, and a proportional activity wit. 



There are several instances in which a natu- 

 ral order produces several very similar active 



