58 A new Green Colour.—Geritian. 
referred to any other known substance ; 085 of magnesia; 056 
of oxidulate of iron ; 074 of water. M. Gadolin proposes to 
change the name of blue quartz into Steinheilite, as a mark of 
respect to M, Steinheil, Governor of Finland, who has distin- 
guished himself as a mineralogist, aud was the first. to remark 
that this species should not be confounded with the quartz.— 
Revue Encyclopédique. 
A NEW GREEN COLOUR DISCOVERED BY M. BIZIO OF VENICE. 
In repeating the beautiful experiment of Brugnatelli on the 
colouring matter of coffee, 1 had occasion to observe some new 
phenomena. When a drop of the infusion or decoction of 
the grain fell upon a piece of cloth, it formed a yellow spot sur- 
rounded with a beautiful green border. I attributed this green 
colour to the oxidation of the oil of coffee. In order to fix that 
colour I boiled a hectogramme of coffee powder and reduced the 
decoction to eight hectogrammes. I added an equal quantity of 
sulphate of copper dissolved in water, and used as a precipitate 
a solution of caustic soda. A deposit was formed weighing 105 
grammes, which on drying in the air took a green colour; the 
more it was exposed to the air while it remained humid, the 
brighter the colour became. Water, ether, alcohol and the al- 
kaline subearbonates had no effect on the colour. Ammonia in- 
dicated the presence of copper; caustic potash changed it to 
sky blue, and took itself a green colour; caustic soda did not 
alter it, and received but a slight tinge of the green. 
The deposit, which is a true lac, resists acids sufficiently well, 
and, with the exception of the sulphuric and oxalic, no others 
destroy the colour totally, Acetic acid in dissolving this lae pro- 
duces a solution of a much finer green.— Annales Generales des 
Sciences Physiques, par MM. St.Vincent, Drapiex et Van 
Mons. 
The Editor of the Bibliotheque Physico- Economique, after an- 
* nouncing the preceding discovery, affirms that twenty years ago 
a Frenchman named Magnan, of Chaumont (Haute-Marne), 
had by accident discovered the same colouring property in coffee 
when surcharged with soda. 
4 
GENTIAN. 
Some researches into the cause of the bitterness in the root 
of Gentian (Gentiana lutea) have led Messrs. Henry and Caven- 
ton to ascertain several important facts with respect to this me- 
dicament. They recognised: 1. A very. fugitive odoriferous 
principle. 2. A bitter yellow crystalline substance which they 
have named Centianin. 3, A matter identically the same as 
glue, 
OE 
See ee oe Pee 
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