C|)E $oj>ular detente iSttPS 
AND 
BOSTON JOURNAL OF CHEMISTRY. 
Volume XXIV 
BOSTON, MARCH, 1890. 
Number 
CONTENTS. 
Familiar Science.— Fire 33 
Extraordinary Hailstones 34 
The Proto- Helvetes, or Lake -Dwellers of 
Switzerland 34 
Egyptian Language and Chronology — Char- 
acters of Egyptian Inscriptions — The 
Rosetta Stone 35 
What the Winter Woods Aftbrd 36 
Scientific Brevities 36 
Practical Chemistry and the Arts. — L'ltia- 
marine -37 
A Device for Writing in Moving Vehicles . 37 
The Scientific Knowledge of the Ancient 
Greeks and Romans , . . 37 
The Out-Door World. — Reports from Chap- 
ters of the Ninth Century 39 
Photography 40 
Practical Photographic Points 40 
Editorial. — Pre-historic Rock Inscriptions in 
Sweden 42 
Brief Studies in Biology 42 
An Ancient Indian Village Site 43 
Meteorology for January, 1890 44 
Astronomical Phenomena for March, 1890 . 45 
(^estions and Ajjswers 45 
Literary Notes 45 
Medicine and Pharmacy. — Sleep .... 46 
Monthly Summary of Medical Progress . . 46 
Bacteria, Bacilli, Micrococci, and Microbes . 47 
Pathological Inferiority of the Left Side of 
the Human Body 48 
The Deadly Cold JBed 48 
Medical Miscellany 48 
Publishers' Column 48 
Banjiliar Scieijce. 
FIRE. 
What is fire.' We fancy that few persons 
coiild answer. this question oft' hand, although 
the phenomenon of combustion is perfectly 
familiar to everyone. The ancients consid- 
ered fire to be one of the primitive elements, 
like the earth, air, and water, — all of which 
la.st we now know to be compound and not 
elementary substances, — and this idea of an 
elementary fiery principle survived under the 
names of phlogiston, caloric, etc., down to 
the time of Lavoisier, and was not entirely 
overthrown until after the beginning of the 
present century. 
We have, in the preceding paragraph, 
spoken of fire as a phenomenon, and that 
is exactly what it is. Fire is not a substance ; 
it is not even an immaterial force, like light 
or heat ; but, as generally understood, is 
simply the sensible phenomena of light and 
heat resulting from an intense chemical 
reaction — generally, but not always, a pro- 
cess of oxidation. We may dissolve a piece 
of zinc in sulphuric acid, b}' itself, or do the 
same when it forms a pole of a galvanic 
battery ; or we may heat it until it bursts into 
ftame. In all these cases the process is a 
similar one, — that of oxidation, — but fire 
accompanies the process only in the last. 
There the oxidation takes place so rapidly 
that the heat .set free is not- only suflicient to 
be detected by our nerves of sensation, but 
the resulting particles of zinc oxide are heated 
to such a degree that they become luminous. 
So if finely divided metallic iron is exposed 
to the air, it gradually absorbs oxygen and is 
converted into rust. But if the same iron is 
ignited with a match, it takes fire, becomes 
luminous, smoulders away like a glowing 
coal, ami is soon converted into a similar 
oxide, or rust. Just as much heat is set free 
in one case as in the other, the only difference 
being in the rapidity .of its development, 
which determines whether or not it shall 
become evident to our senses. When hydro- 
gen and oxygen gases are burned together, 
as in the oxyhydrogen blow-pipe, the result- 
ing flame, although one of the hottest known 
to us, is almost invisible, and to the eye alone 
there is no appearance of fire ; but introduce 
a piece of metal, or a lump of lime, or other 
refractory substance, and the brilliant lumi- 
nous phenomena at once indicate the intensity 
of the chemical combination which is taking 
place. 
Fire is not always dependent upon a pro- 
cess of oxidation. A mixture of iron filings 
and flowers of sulphur is readily ignited, 
forming ferrous sulphide ; and sodium, potas- 
sium, copper, and some other metals readily 
burn in the vapor of boiling sulphur, giving 
rise to the same igneous manifestations as 
when they combine with oxygen. Nitrous 
oxide, or laughing-gas (N^ O), also sup- 
ports combustion, although the reaction is 
one of true oxidation, the same as with pure 
oxygen or air. 
A very important distinction must be 
drawn between fire and flame ; the latter 
is merely an incidental manifestation of the 
former. Burning charcoal simply glows and 
wastes away ; there are no combustible gases 
formed, and the chemical reaction takes place 
only on the surface of the coals. With wood, 
oil, wax, tallow, etc., the heat produced by 
the oxidation sets free from the unconsumed 
portioii, a large quantity of hydrocarbon 
gases, which take fire and burn at a distance 
from the original burning body, exactly as 
the gas which we burn in our houses is 
driven oH' by heating the coal at the distant 
gas-works. If we burn a piece of magne- 
sium,^ flame is apparently present, but it is 
only the incandescent particles of oxide as 
they fly off" into the air at a white heat. A 
similar artificial flame may be made from 
charcoal itself by finely pulverizing it, throw- 
ing the dust into the air, and igniting it. 
Serious explosions have occurred by dust 
igniting in this manner, but such phenomena 
are nof, strictly speaking, true flames, which 
are only produced by the combustion of 
gases. 
A word shouU be said in reference to 
electric lights, wliich are simply masses of 
carbon heated to an excessively high temper- 
ature. There is no true fire or oxidation 
about them, but a transformation of electrical 
energy into heat and light. There is an 
oxidizing process at the foundation, however, 
and the heat of the oxidizing carbon in the 
furnaces under the steam boilers which fur- 
nish the power to drive the dynamo machines, 
is just as truly transferred through the wires 
to the distant electric lights, as the water from 
tile pond or stream is transferred through the 
pipes to the dwellings of the city. In one 
case it is the tiwnsference of energy, in the 
other that of matter. 
The knowledge of fire is a distinctive attri- 
bute of mankind. No ape, however intelli- 
gent, has been found but what regards it with 
terror, and no race of men — with, perhaps, 
one or two doubtful exceptions — but what 
enjoys its numerous benefits. It is hard to 
say how it was first brought to the knowledge 
of mankind. The Greeks considered it a 
direct gift from the gods ; but, disregarding 
that belief, the lightning-stroke,* the volcano, 
an accidental spark, from the striking of a 
stone, falling upofi dry leaves, or even, as has 
been suggested, by a drop of gum exuding 
from a tree acting as a natural burning-glass, 
— any or .all of these causes may have intro- 
duced this useful but dangerous servant to 
mankind. Once discovered, the knowledge 
seems to have been carefully preserved, and 
the art of producing fire has advanced 
through the fire-sticks and drills of the 
savage, to the flint and steel, and friction 
matches of later times, until in this modern 
age of electricity a touch of the finger is 
suflicient to produce an electric spark, which 
will instantly ignite the fires and gas-lights of 
the largest building, or, if desired, those of an 
entire city. 
