which the oxygen is condensed, and the 
light and heatgivenout, as theFrench che- 
mists assert; nor are heat and light speci- 
fie substances, differing from other matter, 
All bodies which have a strong chemical 
aihnity or attraction for each other, are 
found to possess two different states of 
electricity. ‘Thus, acids are negative, 
and the alkalies positive. Zinc and mer- 
eury, and other metals which possess 
_ Strong ‘Chemical affinities, are also'in dif- 
“ferent. States of electricity. This diife-’ 
rence in the natural states of electricity, 
Dr. Davy coisidered as the cause of 
Chemical afirity. Combustion is. the 
‘eflectoi chemical action. In such bodies 
as combine rapidly together, the parti- 
cles are vislently agitated; andy being se- 
parated. from each otber by their polar 
repuisions, are thrown off in straight lines 
through free space, and become radiant 
heat and light. According to Dr. Davy, 
_ the!particles of all bodies possess pularity. 
k 
powerful affinity, and combines with great 
rapidity; and, during this violent cheini- 
“eal, Action, much |; wht and heat are pro~ 
duced, Some of the French chemists 
have asserted, that oxygen is the only 
support of combustion, and that the light 
and heat given out comes from the oxy- 
~genalone. But light and heat are pro- 
duced in a variety of instances without 
“the presénce of oxygen. “Indeed, in all 
cases where bodies rapidly combine, the 
phenomena of combustion takes place. 
—The new metal potassium, or the metal 
of potass, was placed in a glass vessel 
filled with carbonic acid gas; by the heat 
of a spiritianp applied to the glass, the 
metal inflamed in this gas, and gave out 
a brilliant light. Charcoal was deposited 
on the side of the glass. In this experi- 
ent, it may. be said, that the oxygen of 
he carbonic acid) combined with the 
potassium; butit ought to be recollected, 
Hratithis oxygen had given out its hight 
and heat. According to Lavoisier, when 
combined with charcoal to form ear- 
monic vas, it ought not, therefore, to 
give out asecond time what it had be- 
e lost.—In another experiment, pot- 
assium and arsenic were placed ina close 
eturt, containing nitrogen gas; by the 
P of ‘the spirit lamp they combined 
ch light and heat were prodaced, 
oif the experiment was properiy 
de, no oxygen was present. Metals 
» inflame spontaneously in chlérine 
Soe tetrad called oxymuriatic acid 
‘bis yas, Dr. Davy. statedy was 
wruty Mac, No, 211. 
ie 
Litsrary and Philosophical Intelligence. 
With many. bodies oxygen has a most, 
idiy, and, during their consbination) | 
poles, hike the large magnet, 
265 
a sinple uncompounded substance, cot- 
taining no oxygen. His experinients on » 
this subject we shall afterwards mention. « 
—Ieat is radiated from the surfaces of 
all. bodies, but im different degrees, ace 
cording to their nature and colour. Black 
surfaces absorb aiid also emit radiant 
heat more rapidly than others. If a po- 
lished surface of metal, and an equal 
surface of charcoal, be heated to the 
same degree, and a thermometer be 
placed at the same distance from each, 
the charcoal will raise the thermometer 
more rapidly than the polished metal. 
This radiation of heat Mr. Leslie bad 
attribuled, to certain, aerial pulsations. 
Dr. Davy stated, this could not be the 
case, foc heat was more powerfully, ras 
diated, in vacuo thay in the. open air. 
Iie placed a-platina wire in vacuo, and a 
therinometer at-a certain distance from 
it; the wire was then ignited by means 
of the voltaic pile; the effect on the 
thermometer was greater and more rapid 
than when the same experiment was re- 
peated in the air. All the metals, are 
fused more rapidly in vacuo than in the 
open air, when acted upou by the voltaic 
pile, and give out a more intense devree 
of beat and light. Charcoal, in the same 
circumstances, ignites with a most brile 
Jiant light; and uns light may be continu. 
ed for any jength of time, without any) 
change or decomposition of the charcoal, 
The light and heat, in these experiments 
caniot proceed from combinations. of 
oxygen, but may be supposed to origi- 
nate from the vibrations or violence wf 
action of the particles of the. badies 
which are, thus operated upon... This 
Opinion was also adopted by Hooke and. 
Boyle. The experiments of Dr. Hers 
schel had shewn, that the sun constantly 
emitted invisible rays, (distinct. frou 
hight,) which produce heat; other inyie 
sible rays are, also emitted, which have 
the property. of reviving metailic calces. 
The one he calls, heat making, rags, the 
other, deoxydizing rays. Dr. Davy’s 
Opinions respeeung light, and other rays 
emitted from the sun, imply, that he does 
not believe any of these phenomena will 
admit of an explanation by the’ pulsas 
tions ofan ethereal medium. His obser- 
vations lead tothe supposition, that the 
particles. of hght and of other bodies 
possess polarity —Ifa magnet be broken 
into any given number of parts, each 
‘part has, its attracting, and. repelling | 
Ifa blunt 
insulated metaliic conductor be brought 
nearan excited glass cylinder, it acquires 
2L electrical 
