New-York tribune., 1874-03-14
APPLIED SCIENCE.


BrEAcurNG SHELLAC BY BoNE-BLACK AND sun
tIGHr.-Shellac blcachod 10y the ordinary process
affords polish for light woods. So. that is oii'o
and liable to peel Off while the presence OF 'Iaco
of chlorine causes metallic inlaymg TO become u'iu
These defects may be avoided by diiicfeh' n'ouc VI
bleaching namely by adding fine granuia'ed pone Slt
black 20 the solution of shellac IN w pei Scn' @
sinohol until , tin nasty mas, is formed, ana eN-
nosing Tins for several days 10 direct sunlight,
occasionally shaking n 'Aofous"i9 "'''
when sufficiently 6ieacheu
TgE MAGNETISM or ELEcTEo-MAGNEIS'-S
0,neain as the conclusion of an extensive ihNosu-
cation into the construction OF electro-magnetS'
tates that in order 10 explain his observations IL Is
nscesSsry 20 conclude that bar of iron contains
two shells of positive magnetism separated
by q layer of negative magnetism One can easily
see how TO superposc o greater or less number of
layers alternately, positive and negative, by pass
ing through the coils of the electro-magnet
moderate number of alternately positive and
negative currents of diminishing intensity, the law
of dimmutiOn not being matter ot chance
II is. however, necessary that the intensity
NJ the induced current should decrease
with 3 definite Tapidlty. When thus intensity
diminiShes too slowly the iron which IS SnDnitieo
to it's influence is in the same state If 1t had been
submitted only to the influence of current feehler
than that which has been employed. II ls the9
feeby magnctizcd. and If subjected TO action 0l
current OF greater intensity IT smagnctizcdDq
IN both the positive and negative senses. III Ihen
behaves as If it really IN pcutra state. Con
scmently whenever in the course OF his researches,
Gangain desires to domaguetzc bar OF IRON nc SUD
mts At TO the action OF series oi aherhating cur
rents whose intensity decreases gradually ana
slowly. lie suppcses that the same method "oulo
70 dcfuaeh6tiIc steer
TuE HrrrorIcToR 4 NEW ARTICLE or PHOTo-
GRAPHIC ArPAEArUs.-Tbc recognized value of
photography in furnishing representations OF OBJ
ecs Of scientific interest. free from subjective de-
feots has led Dr. Stein 10 devise arrangement for
DISPENSING " ith dark room and reducing the time
required Tor taking pictures. His apparatus, as eN-
hbitod at the Vienna Exposition. consists essentially
m an improved platehOlder, in which the collodio-
nized plate is sensitized. exposed and developed,
without removal from it, by successive admission OF
the usual solutions, through separate tunnels, the
progress being noted through yellow glass aper-
lures. and the apparatus cloanscd. after each
,nprcaSon by stream of water passed
through It, In addition to specimens III natural ms
tory and subjects met with in medicine and surgery.
1T is adaped, by use of the highly aCtlnlc magnesium
light to copy the views of interior portions OF the
. body obtained by specially constructed urethro-
SCOPE OpihamOscOpc, OrosCOpe and laTNneoSCOpe'
and may also he used with tho solar nlcroScope on
telescope IL is also claimed 20 be especially adapted
to military purposes While. however NJ NAV he as
simple and easily compIcheTded as - claimed IT. Is
TOO much to expect that any one enilrelS unahllar
with Photographic processes would he able, mechan-
icaly aud ~ once to operate with il successfully as
the statements made might lead one to iuier
Tue F,rsr RrrorT OF rmE BrrnSn ASSOCIATION
COMMITTEE on DYNAMICAL AND ELECDuCM CNIis
The first report of this Committee was made at
the recent meeting If the British Association for the
Advancement of Science and is confined principally
to the selection aud nomenclature OF units OF force
and energy, under which head the Committee Is
itsef prepared to offer certain definite recommenda-
tons winch are as follows: lst The gramme, cent?
meter and second are recommended as che UNITS OF
mass length and time, respectively; combination
winch has tho advantage OF making the
unit of mass appear identical with the
mass Of the unit volume of watcr-in other
words Of making the value cf The density of water
appear equal to unity From these fundamental
units the units OF electrical and magnetic magni-
tudes now in common use, may he derived; and II
Is recommended that, until special names shall be
prepared for them they I've distinguished from abSo
luto UNITS otherwise derived. by The three initial
letters G. G.. : As regards the name to be given to
the C. g. s. unit of force IL is recommended that il
Le derivatyt of the Greek word dan0mfs-the form
.lynamy appears 10 be the most satisfactory 10
eiymojoojets The work done bv this force working
through a cenGucter il the c. G.. ). unit OF work.
H i3r Tn.on m "a II a. q: S uit IF power is the power
of doing work at the rate of one Gg. per
saeond aud the power 0l on engine can be specified
IN rgs per second. The common and extremely
fourhs OF an crg per second. Tor me expression Of
hiph decimal lRultipieS ana sub-nUtiplcs. the sys
ten introduced by Nh. SiOney is recommended 1t
consists IN dCuOtmg tho exponent OF the power Of
tens winch serves aS multulier, by an appended
cardinal number # the exponent be positive, and
by A prc.iKcd OTdlnal number when the exponent
i negative thus ten I" the ninth power. or one
thousand million Qrammcs constitutes " "raInme-
nine and the one thousand milloDth OF grammc
constitute A Dinth-gIWnmc
PA,rEuE Process FoE MAKIVG UNnTFB,BIG
BrrR-Pasteur. the eminent French chemist, has
recently given method for preparing an unaltera-
BILE beer that is beer which win not turn
spoil upon keeping. II is important to con-
slider two facts as preliminary to this process
In tho frst place, says FaSteur, all the
Questionable changes which beer or must un-
dergo are due 20 the action of minute microscopic
organisms vibriones, bacteria, &c, whose germs
are carried in the air. contained i'll the materials
used or are found adhcring 10 the utensils employed
in the brewery. In the second place under all the
methods Of brewing commonly employed. every
must every yeast and every beer contains these
germs Without their presence beer can only nm
dergo alcoholic fermentation, and possibly some
minor changes which may in certain cases improve
its quality, and in other produce nothing
worse than vapdity. The thing to be done. there
fore. is TO prepare must free from Objectionable
germs and to feIment it by means Of an yeast SIM
ilarly pure. Pasteur proceeds as follows:
The must prepared by the ordinary methods
~ heated very hot in order 10 destroy all germs con-
tanned IN u. Ii is then incOsed IN a val provided
with tight cover whose interior communicates with
the outer air only through two vertical tubes. AT
one Of these tubes current If carbOnic acid is
allowed 10 enter Its excess beng discharged by the
other In this vat, thus sheltered from all germs
which might otherwise get III from the ar, the must
is allowed to cool Tho next stepis TO add the yeast