CHEMICAL SCIENCE. 2G1 



The methods generally in use at the present tune for the detection of oil of 

 turpentine in other ethereal oils are as follows : 



1. To rub the suspected oils Tjetween the hands, and to detect the adultera- 

 tion by its peculiar smell; or to insert a strip of paper into the same, then to 

 light it, and extinguish it a little while after -.van Is, when the peculiar smell of 

 turpentine will be remarked, if it is present in any considerable quantity. 



2. To mix the oil in question with an equal quantity of 80 alcohol, when, 

 if it contained any oil of turpentine, fennel, or anise, no complete solution 

 will ensue. 



3. Oil of turpentine will not dissolve red sanders, though many other 

 ethereal oils will, whereby this property will be diminished, if any oil of tur- 

 pentine had been added. 



4. Iodine, if brought into contact with oil of turpentine, will raise a slight 

 explosion; but not so with many other oils. Yet, if the former had been 

 added to the latter, and if even in only small proportion, a similar effect will 

 result. 



ON TIIE AMOUNT OF CAFFEINE ES T COFFEE-BEANS. BY PROF. 



A. VOGEL, JR. 



The method hitherto employed for the extraction of caffeine from coffee- 

 beans and tea-leaves, is both complicated and uncertain. It consists in 

 extracting the coffee-beans with water, precipitating the tannic acid from 

 the solution by lead salts, and evaporating only the solution freed from lead 

 for crystallization. This method is exceedingly inconvenient, and this is 

 probably the principal reason why the statements as to the amount of 

 caffeine in coffee differ so much from each other. 



The following method appears to the author to be much simpler, and to 

 lead to more accurate results. It is founded on the treatment of powdered 

 coffee-beans with commercial benzole. This extracts two constituents from 

 the coffee oil of coffee and caffeine. After the evaporation of the benzole, 

 these two substances may be easily separated from each other by agitation 

 with hot water, in which the caffeine dissolves, whilst the oil floats on the 

 surface, and may be skimmed off. The caffeine is obtained by the evapo- 

 ration of the aqueous solution, in very beautiful crystals, which may be sub- 

 limed. 



The whole of the benzole may be recovered, by distilling it in a retort, 

 after it has stood about a week upon the coffee-beans. The residue in the 

 retort is the oil of coffee and caffeine, which may be separated as above by 

 agitation with water, or by treatment with ether, which dissolves the oil 

 and leaves the caffeine in crystals. By this method oil of coffee and caffeine 

 might by obtained as subsidiary products in benzole manufactories. 

 Kunst-und Gewerbeblattfiir Baytrn, 18-38. 



EJECTION OF MINERAL ADULTERATION IN FLOUR BY CHLO- 

 ROFORM. 



A chemist at Charleville has contrived the following procedure, by which, 

 according to M. LassaiL r ne, a ten thousandth portion of mineral matter may 

 be detected in flour adulterated with the same. A glass tube, three centime- 

 tres hi diameter, and from fifteen to twenty in length, closed at one end, is to 

 be tightly corked at the other, so that fluid may be well shaken in it. From 



