APRIL 22, 1897 | 
NATURE 
393 
§ 4. The following flames and burnings were tried :— 
(1) Candle. 
(2) Paraffin lamp. 
(3) Spirit flame. 
(4) Portable electrometer matches. 
(5) Coal-gas (Bunsen. flame). 
(6) Hydrogen flame. 
(7) Glowing charcoal. 
(8) Glowing coals. 
§ 5. The method of experimenting was to place the burning 
substance in position at the bottom of the funnel, to insulate the 
quadrant of the electrometer in connection with the electric 
filter, and to start working the air-pump at the rate of one stroke 
per three seconds. The time of each experiment was ten 
the long vertical tube through which the acid was admitted, 
indicated the pressure under the nozzle, above which the 
hydrogen was burning. 
§ 6. In the case of the charcoal and coal, the burning fuel was 
placed at the bottom of the iron funnel in a thin rectangular 
metallic vessel with small holes perforated in the bottom and in 
the sides. A wire from the case of the electrometer passed 
through one of these holes, and was thrust into the burning fuel. 
It was noticed that when the burning charcoal was first put in 
position below the funnel it always produced negative electrifica- 
tion, which ultimately changed to positive. Thus, in four 
experiments, the electrification, which was at first negative, 
became positive after 8, 10, 14, and 18 minutes respectively. 
On investigation it was found that as long as any flame! was 
visible in the burning charcoal the electrification was negative ; 
Is Oya s FIG 
Fic. 
minutes (200 strokes of the air-pump). The results obtained 
are given in the following table. In testing the electrometer 
Sensz‘Yoeness of the electrometer, 111 scale diwestons per volt. 
|Number off Mean deflection P Fealh 
experi- It scale divisions CLA he 
| volt 
| ments. of electrometer. aut: 
| 
(1) One candle a 2 go neg oS neg. 
(2) One paraffinlamp... | 
(z) without glass funnel — 2 l\ Sale On7G. a5 
(6) with glass funnel ... 2 Sus 0727 
(3) One spirit lamp .. 4 | 109 ,, 0-99 55 
(4) Four portable electro- 
meter matches 6 2 2240 203) 55 
(5) One Bunsen flaine ... d 38) 5) O27 vas 
4 3 7 
, 
At low pressure gave small negative; 
) eke higher pressures large positive. 
| No electrification was found from 
| the jet at any pressure when not 
| burning. 
| Both gave negative electrification 
( | when there was a flame ; and both 
‘| gave positive electrification when 
they were glowing without flame. 
(6) One hydrogen flame 
(7) Charcoal 
(8) Coals 
matches, four matches were stuck in holes in a metallic plate, 
and the plate connected bya wire to the case of the electrometer. 
These matches, according to a suggestion made more than thirty 
years ago by Faraday, are made of white blotting-paper soaked 
in a solution of nitrate of lead, and rolled up with paste into 
little rods of about five millimetres diameter. The hydrogen 
was generated in an ordinary Woulffe’s bottle from zine and 
hydrochloric acid. The rise of the dilute hydrochloric acid in 
NO. 1434, VOL. 55] 
Hl 
So DP 
TH 
4 
E= 
but as soon as all the flame disappeared, leaving only the red 
glow, the electrification became positive. To test this the heated 
1 In a paper on ‘Electrification of Air by Combustion,” by Magnus 
Maclean and Makita Goto, communicated to the Philosophical Society of 
Glasgow on November 20, 1889, is a statement of results of many observa- 
tions to find the potential to which the insulated quadrant of a quadrant 
electrometer is raised when in metallic connection with various kinds of 
flames and fires. [tis there said : ‘t The effect of an ordinary lucifer match 
is very interesting. While the match is burning with a flame the deflection 
indicates positive electrification ; but after the flame ceases the electrifica~ 
tion becomes negative, the effect now being that of glowing charcoal." The 
following table is quoted from the paper. In some cases the burnings lasted 
so short a time that quantitative determinations of the potential were not 
obtained. It is conceivadde that all of the complementary opposite electricity 
separated from that which went to the electrometer in those experiments 
went to uninsulated solids in the neighbourhood. The experiments de- 
scribed in the text demonstrate that some of it was lodged in the air and 
fumes proceeding from the fire or flame. 
Substances giving flames or Electrification of Greatest observed 
burnings. insulated fuel. potential in volts. 
Charcoal 250 cc fi Negative | 3/0 
Lucifer match, wood, and paper 
glowing... ap fc aaa 9 370 
Hydrogen ace ene a5 re 06 
Iron burning in vapour of sulphur) Ss = 
Copper ,, 9 FA Bs ie = 
Paraffin lamp “Ae a Positive 06 
Alcohol lamp... aed aa ef o3 
Sulphur a0 oe aa m | 2'0 
Phosphorus exposed to air 7 | 15 
Magnesium : ae = 
Iron burning in oxygen cat » 
Lucifer match, woud, and paper 
burning with flame ois Re — 
Bisulphide of carbon... a 7 o'6s 
Sulphuric ether ... Foo ana on o'9 
Turpentine eral cee en at o'5 
Bees-wax ... reo ce mee PP o'7 
Camphor ... 2a Bo tee An 
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