The Princeton union., 1893-12-28
SCIENCE ANU INDUSTRY
USEFUL INFORMATION FOR THE
CURIOUS. ss
.dustca1 Anal, sis of Gnses-The New
French Battle Ship-Electrlcity in
Sugar Rcfin1ng-.A Light That Fail
cd-Science Notes.

The eminent French scientist, Castor
Tissandier, describes all absolutely new
method of determining the quantity of
foreign gas contained in air by the pass
ing Of the gaseous mixture through son-
orous tubes. The invention is credited
TO M. e. Hardy, a distinguished French
physician, who calls it the "formcne-
phone" and intends it primarily for the
detection Of fire-damp in mines. Vari-
GUS scientific apparatus have been de-
Vlsed for this purpose, but few have
turned out to be practical. One of
these is the fire-damp metOr of NJ Co.
quillion, perfected by NJ. Grehaut This
certainly measures the quantity of gas
IN the air, but is too delicate for the
wear and tear of mining work. One Of
the best Indicators Of gas yet known is
the safety lamp, in which the presence
OF the dangerous fumes is made mani
fest by the appearance Of an auroele
around the flame Of the lamp. The
radical objection to this method of de-
lection is that the aureOle doesnOt show
itself until such a quantity Of gas is
present as constitutes a critical danger
The formenephone, on the contrary,
oA' So uilC liAb1CtlIlOuo Ill IL ltN ScCOlltlS.
The principle on which it is based is
that when two organ tubes giving the
same pitch are subjected to The intil-
ence of two equal blasts of pure air the
sound produced is identical. But, every
thing else being equal. if one of the
tubes is blown into by mixture of air
and gas of different density, the sound
of the tube is corrcspondingly modified,
and the vibrations produced are more
or less frequent as more or less gas is
mixed with the air. This occurs with
such unvarying results that NJ Hardy
has been able to lay down a regular
scale of vibrations and their signiti-
canoe for the guidance of those using
his Invention. The apparatus consists,
briefly of two blowers, or pair of bel
lows, inclOsed in air-tight metallic en-
VelOpeS. One Of these cases contains
pure air only, and to the other is con-
Quoted by a pipe the air Of part Of the
nine to be tested The air in each re-
ceptacle is blown hy the disengagement
Of a weight on the top Of the bellows,
whereby downward and forcible pres
sure is Immediately produced, into the
organ tube with which each receptacle
Is provided The resultant sound is so
intensified by 4 special adoption of the
microphone and the telephone that it
can be distinctly discerned, and com
parison of the difference in sound Of
the two tubes gives an absolute indica-
ton of the quantity of gas in the air
tested. In order to secure greater precis
ion in the record Of this indication, u
register is provided Oh which the num-
Der of beats given per second is mark
cd, so that all chances Of inexactitude
are eliminated. While this invention is
designed mainly for use in mines, it is
equally applicable to the analysis Of a
mixture Of air and any gas not having
the same density, and especially mix
tulre of air and carbonic acid. Installed
in a room Of ordinary dimensions, it
will tell exactly to what extent the air
has been vitiated by the presence Of
one Or more persons in a given time.