New-York tribune., 1874-09-21
APPLIED SCIENCE.


TESTING MrLK-As result of investigations, Prof
SAGE proposes as test for the dilution OF milk, mix
ing IT with its volume of alcohol OF 7Oo Tr. when
with pnre milk the coagulum formed viii equal the
milk in volume and invariably rise TO the top.
wr,-r,xc CoA1 4 MysrAKE-It has frequently
been maintained that wetting coal increases 'io
amount of heat given out in combustion but care
full inquiry has shown FIRST that there is no
Of heat second that q loss of heat always 49,
addition of water third both the alnoun, ~ SrnbIv
and the temperature Of the hre arc
diminished
DETEcT1oS or SrARCH IN MILK'-Dr' magyar az
counts for occasional discrepancies III tue
of different chemists iu regard to the presence Oh
starcb in sample of milk by the peculiar property
which lacteo-protein substances possess OF eomon
,ng rapi5lv with iodine and thus decolorizing So
Infion of H. In consequence no reaction Tor staich
is obtainabe untli the mix Is oident chemist
NAV stop short of tins point, ana tali 10 get 'ne
reaction for starch
So1rBLr SrsoUIoxIDE OF IRON IN DYEING SILK
The injurious effect of the usually very acm NOR
dants upon the durability Of silk may be avoided Dy
eronoving the aoueous solution of peroxide OF ron
which remains in dialyscr. supplied with bottom
of animal membrane parchment paper, and hl'eo
with solution Of chloride of iron, and noatec iol
some time in vessel of water, the larger paTt q
the hydrOchlOric acid passing llto the water 1hl3
solution is also much more enecJlNe lhal Ihe usu"l
iron mordant since The affinity OF the IRON 1or the
siik is not weakened by an acld. In fact mOr1dnt-
lug by salts seems itself to rest upon ui"J TIC
process.
DIREcT PHoroGRAPHY OF THE SOLAR PRoTUBER-
ANcEs-Prof Sellack OF Cordoba, who has the use
of 13ipeh Photographic objective narrates MS eX-
nerienee in attempting the photography OF solar
protuberances by means Of the spectral Ine H.
gamma According to him, thin layer OF iodide OF
silver upon plate of glass absor6s all the Vioet
light Of the spectrum and he therefore proposes 10
cover the surface of his lens with thin LAYER OF TINS
substance BY means OF the hight that Is then Trans
mitfed he would directly photograph The sonar pro
fuberances. His first attempts Tor many reasons
have been quite unsatisfactory; but tle suggestion
seems worthy of further development by those spec
trOscopists who have greater cOnEenlehceS az theH
command.
REGENERATION OF OIL-PAISTNGs.-Besid the
irremedable darkening Of oil paintings byage they
are also liable 10 deterioration by the cracking OF
the paint on severe drying, aud also to loss OF bil
laucy by the formation Of numberieSs small rs
snres in the originally transparent, heavy MIN OF
Ysrnish upon them The former defect eau only be
removed by the tedious filling of the cracks with
fresh paint. AS a means for remedying the latter,
Dr. Weiget suggests, as an improvement on pan
proposed BY PettenkOter, that the VaInlsh pe par
fiallv dissolved and the assures thus nlled up, Dy
leading upon the picture through gI oIyiDS' HDe' II
bv means of a bellows, through flask containing
alcohol, and gently warmed
EXPLOSIONS OF FIRE-DAMP IN Coal MINEs.-The
subject of the connection between explosions in coal
mines and the weather has attracted the attention
of Messrs. Scott aud Galloway III England during
the past four years Their third report has recently
been presented covering the year 1873, from which
it appears that the number Of fatal explosions was
90 causing the loss of 1G3 lives. OF these explosions
hS per cent are due to changes of barometrc press
ure: II per cent to great heat . per cent are not
attributed TO meteorological agencies. Inc NUMBER
of explosions not found to have any apparent de
pendence upon the direction from whlch the WI Wiuu
blows, The results place u beyond the possibility
Of doubt that the escape of re-damp ana the con-
sequent explosions are related mainly to the eOndl
1iOns of atmospheric pressure, and that cIeiuI
watch the barometer is, above all necessary III
each cOllery.
QUANHArIvE DIFFERENTIATION OF TANNIc ACID
The following method, by Terrell, is regarded as
sufficiently Trustworthy for techuologca purposes,
although other organic substances beside tan
min act in "a similar manner. 1t rests upon the fact
that O1 gramme of pure tannin will absorb - cubic
centmeters of oxygen. graduated glass tuoe,
with a glass stop-cock at the bottom and ground
glass stopper at the top, is partially filled with SSs
per cent solution of potash and the substance III
which the tannin is to be determined is introduced
as finely pulyerized as possible and wrapped IN IN
sized paper, aud the tube then closed the ielIpea-
fnre and barometric pressure being noted at the
same time. The liquid Immediately begins to turn
brown and after q hours the amount OF oxygen aD-
sorbed is read of, by opening the stoP-cock under
water and from 1t the quantity OF tahhh present Is
calculated.
THE EVAPORATION OF LIQUIDs-Stefan has en-
deavored 10 reduce to some definite laws the phe-
nomeua of the evaporation of liquids Especially the
diffusion of vapors and has made series of expert
rnents principally on the evaporation of ether. He
finds that in narrow open tubes the velocity Of the
evaporation is uversely proportional 10 the distance
of the surface Of the liquid from the open end OF
the tube Ii is independent of the diameter OF the
fnbe and increases with the temperature, so far as
the vapor pressure increases with the temperature
If the pressure Of the vapOf becomes equal 10 that
of the air the formula given by Stefan shows that
the liquid then bois the evaporation takes pace
at such q rate that the times IN which equal numbers
of bubbles form are proportional TO the numbers o,
5. Z, &c. III the tube contains hydrogen lnstead oI
ar. the bubbles form in one-fourth OF the tlme or,
10 other words evaporation proceeds IOur times as
rapidly IN hydrogen as III alr
CONVERSION OF ORGANISATIONS MATTER INTO
FUEL.-Dr. Petn of Berlin has perfected process
for producing odorless blocks of fuel from excre-
ments. which also burn without odor, with heat
ing effect equal to brown coal. and aifordng an ash
excellent as a phosphate fertilizer. The excrements
are first rendered perfectly odoress in the recepta-
cles before removal by the addition of chemically
prepared powder. and are then concentrated by
evaporation in peculiarly constructed vessel with
out the least annoyance to persOus present., to the
consistency of CLAW and the mass then delivered
ly the machine to be cut by wires into blocks.
which are pressed and dried like bricks. IL Is not
necessary 10 separate solid from liquid eXcrements,
and the disnfected matter can be transported az
any time without annoyance 70 any one. since the
machines act rapidly and without requiring many