226 Mr. Murray’s Chemical Observations. 
addition to our stock of means for imparting scientific _know- 
ledge to the juvenile mind. 
CHEMICAL OBSERVATIONS: BY MR. MURRAY. 
1. Singular Modification of Temperature by Copper and Silver 
Leaf. 
When we grasp in the hand a few foils of copper or silver 
leaf, a peculiar glow of temperature is communicated and felt. 
I found that a delicate thermometer placed in the hollow of 
the hand, the ball completely enveloped, indicated 98° 5! F. ; 
with the ball wrapped round with loose copper leaf, the tem- 
perature shown was 101° F.; with silver leaf, 101°+ F.; with 
mixed silver and copper foil, 99° 75’. 
2. Aphlogistic Phenomena of Gum. 
If a portion of powdered gum arabic be placed on a dise of 
platinum and burnt to charcoal, it will, when ignited, continue 
long to glow in that state: let fall on paper it ignites the 
paper; and placed on the platinum wire of the “lamp with- 
out flame” it continues aphlogistic with the coils, and it will 
ignite a sulphur match, &c. 
The platinum cage supplied with these aphlogistic live coals 
produces a fine effect ; and when even the platinum has become 
extinct, they will continue to glow and give light, and the 
reignition of the wick is more certainly secured. 
When the aphlogistic gum is introduced into a glass cylinder 
containing a portion of ether, it will glow in the superior part 
of the vessel; when immersed too low and brought near the 
surface of the ether, it will be apparently extinguished ; but 
when raised to its former position it will be rekindled, and 
continue to glow with additional brightness. There is this 
difference, however, between the platinum and the gum; there 
is no appretiable waste in the former, while there is a sensible 
expenditure in the latter. 
When this substance reduced nearly to whiteness is intro- 
duced into the lower part of the flame of coal gas, the starlike 
brilliancy is excessive. It will be easy now to account for the 
peculiar intensity of light which supervenes on introducing 
into the exterior verge of common flame, platinum wire, bits 
of straw, &c. reduced to whiteness,—the brilliancy ef mag- 
nesia, &c. before the ignited gas in the compound blowpipe, 
&c.—these being al] reducible to the class of aphlogistic phae- 
nomena. 
3. Liquid Aqueous Ammonia, burning with Flame in Chlorine. 
It is well known that if two cylinders, the one containing 
chlorine 
