New-York daily tribune. [volume] (New-York [N.Y.]) 1842-1866, 1864-04-23
sCIENCE AND ART.
American Institute Polytechnic Assecia-
tion.

tion.
A regular meeting was held on Thursday
evening April IA, S. d. TuI,fAy esq, presiding.
A CALoKIC ENGINE.
Mr.. RoPER Of Boston explained, with the aid Of dO'
grams calore engine now in operation at the SAM
tary Fair designed to be used where small power is
suired It's popularity is that it does not use, upon
bic piston common air heated but only the products Of
sombuston The air to supply oxygen FOR the combus-
bon Of anthracite coal is pumpad in; the carbon Is
burned rapidly and completely, under pressure aud tie
resulting carbonic acid gas and uneombned nitrogen
has from the air are passed m the generator to the PTS
bn. which is in the form Of a hollow plunger.
hanged that il is packed and fitted only the top where
here is the least heat. In this way the common diff
splty of ubrieating lot cylinder and piston is obvi
tted The generator Of heat is surrounded yith fire
brick soapstone which prevents the iron from being
burnt The engine Is single Ncting-tbat II, tie power
applied 20 the piston moving in direction, durir
Which movement the air to feed the fire is pumped in
DE momentum acquired at the same time by n balance
ywhee is used 10 carry the p ton back 10 its orig
hal position The diameter Of the arpump in the en-
zine the For is ~ inches that u It's piston j. 10
inches the difference in the Of the pump and pis
cn multiplied by the usual pressure. eight pounds per
tquare inch shows that this engine exers twohorse
bower II requires about 10 pounds Of coal per hour
!. occupies five square ieet OF ROOM and weighs @V'O
Er BARTLETT thought this par for using TIRE products
Of combustion one justly deserving our careful con
federation.
The CHAIRxAx said en- engine was invented by Banch-
ard which used both steam and the products Of cOmbus
Ron steamer was built on this plan and for
Zone tine in New.Tork HarbOr A Committee from
his Institute examined IT, and reported saving o..
hel By the arrangement. Bot when the steamer was
out regular route II was found she was not always
10 be relied upon. The combustion in this pan was
tarried on under pressure; the steam used
hde Of piston and the gaseous products Of combustion
IN the other. There vas danger in that Arrangement
hat the cylinder would be marred by the solid particles
b. The products but In the plan before us this defect Is
ssmeded Many persons have been deceived by san
func statements regarding air or eaOric engines. II
not claimed for this plan has been for nearly ell
others Of this eass that 1t is great saver OF fuel In
bct 1t takes Ette more than the best steam ongncs
but IL Is SAFE convenient and will not burn out so
tspdly those having the iron cylinders in direct oon
tAct with the IRE.
DU.IPryG WAGON.
Mr.. DAVIS exhibited a model of q new dumping
saigon which could alo be used for the ordinary work
81 a farm. 1t is Vermont invention. The wagon is
vded into several Compartments and tho load in each
D balanced 80 as % be readily discharged
Prof FLEURY addressed The Association on the Sepa
cation Of Gold from Quartz and other ores.
After abiding to tie ordinary process Of extracting
gold bg means Of mercury, which forms anal gam
kasy separated by heat the speaker said the general
tpinion has been thGt gold 10 times heavier than
faraday has shown that when chloride Of gold in
Solution was placed In bottle, and gradually small
portions OF phosphorus were added the gold instead Of
sinking 10 the bottom, remained suspended in the
bqud, giving to it fine red color Does this curious
sct-explaning 10 as the deporable loss Of least 50
per cent of gold In the ordinary washing processesno
Indicate the existence Of some fixed law by which
heavy bodies may be so finely divided that they may
remain suspended between the atoms molecules Of
liquids or gases
Several processes for extracting gold were adyerted
so and facts presented which the speaker was not
sware had been fully discussed at previous meetings Of
The Association.
IL was stated In reply. that the late Prof Renwick
had explained how gold eluded the grasp of the washer
when the form Of sulphuret, and why the taiings
after being exposed the dir for several year5 would
yield gold ON second washing. Prot. EVERETT said
the process fOr dlsso!ying gold quartz by means Of
hydrOiuOfic acid not economical on account OF the
cost Of making this acid from the decomposition Of uor
spar.
CoLoR-BLINDsTSs.
DR. ROwfLL had placed on The wall some blue cOlored
cards having upon each ons large and one small red
spot be wished 10 show how much the power 10 dsiin.
that the small spot viii appear blue when the spectator
bas removed certain distance. This distance is differ
snt for nearly every spectator.
Mr. GAvIIT said this experiment did not illustrate
What Is commonly known as color blindness, Tor the
thus defective cannot distinguish certain cOOrs
when they are placed quite the eyes. Distance
has nothing to do with color blindness Since different
colored lights have been used signals on railroads
and IN Lighthouses the seacoas tie subject las as
splned great Importance lie remembered that in cross
fDg the Atlantic in 1876 this subject the topic Of
conversation the snip in sight Of a certain light
which was known to be red yet 10 no two perons did
this igt appear TO be Of the same color The number
OF persons decient IN the power ~ distinguish all ue
coo's is much la,gcr than is generally supposed. AZ
bis request Mir Garvey the Secretary read lie fol-
lowing extract Mis- from TIE Popular Science
Rerep; From the calculations OF various authors TINT
person out vi fifteen cOUr blind and from
s4e Invest cations Of the late Dr. Wilson upon l per-
ss~ 1 Edinburgh, male In 1871, we gather that