150 Intelligence and Miscellaneous Articles. 



isting in a mineral water or in a fluid of animal origin is discovered 

 by a green colour gradually developed by the action of the air. 



The property which coffee possesses of rendering albumen green 

 by the action of the air, is derived from the gallic acid which it con- 

 tains ; from which it follows that the reputed green colour of coffee is 

 a product, and not an educt or immediate principle of the bean. Gallic 

 acid renders albumen green ; the effect is gradually produced ; it is 

 strongest on the surface of this substance. As albumen contains car- 

 bonate of soda, it may be supposed that the green colour is derived 

 from the action of this alkali ; and this appears to be the case, for on 

 saturating the alkali of the albumen with vinegar, no green colour is 

 produced. — Plants which contain emeta or veratria are devoid of 

 gallic acid. When tannin is combined with the alkalies, it appears to 

 approach the nature of gallic acid. — Ibid. 



NEW EXPERIMENTS ON THE COMBUSTION OF COAL-GAS. 



The Rev. W. Taylor, of York, in performing some experiments 

 on the combustion of coal-gas, has obtained results which promise 

 to be of public importance. He has discovered very simple means 

 by which the illuminating effect of a common argand gas-burner 

 may be much increased, while its flame is proportionately enlarged. 

 The following brief statement will show the nature of the experi- 

 ments, which have been repeated by several members of the York- 

 shire Philosophical Society, as well as by many inhabitants of York. 



Exp. 1. — A piece of wire-gauze being laid upon the glass chimney 

 of a common argand gas-burner, the flame is immediately enlarged 

 to twice its former dimensions, and its light fully doubled. 



(A similar experiment being tried with a common argand oil- 

 lamp, or reading-lamp with a flat wick, the flame is often enlarged, 

 but so discoloured as to yield less light.) 



Exp. 2. — Place the finger, or a bit of cork, so as to close the 

 lower opening of the interior air-passage of a common argand gas- 

 burner : — the flame experiences a sudden enlargement, with an in- 

 crease of light nearly equal to that in Exp. 1. 



(The inner air-passage of an argand o/Z-lamp being closed, the 

 flame is greatly deteriorated and darkened.) 



Exp. 3. — The air-tube of an argand g«5- burner being stopped as 

 in Exp. 2, and the flame consequently enlarged, no further change 

 happens when wire-gauze is laid on the top of the glass chimney. 



Exp. 4. — Over the glass chimney of a single-jet gas-burner, wire 

 gauze being laid, produced no enlargement of the flame, and no in- 

 crease of the light. 



In an experiment at the rooms of the Mechanic's Institute, York, 

 it was found that one hundred feet of gas were consumed in three 

 hours and twenty-five minutes, by six Argand gas-burners in the 

 ordinary state; while the same gas-b\\Yt\eTS, provided with tvire gauze 

 caps to their chimneys, yielded an equal light for an equal time, 

 but consumed only ahoMt Jifii/ feet of gas. 

 York, Dec. 9, 1828. J. Phillips. 



