The sun. [volume] (New York [N.Y.]) 1833-1916, 1892-07-24
NOTES ON SCIENCE AND INDUSTRY

N. Dronier claims to have perfected now
magnesium lamp which burns for regular
periods Of twenty-four hours without extinc-
ton. Tho light which 1t can produce with one
kilogram (22 pounds) Of magnesium is. he
SAYS. equal to that generated with 100 kio-
grams OF candles. $50 Kilograms OF OIL 80
Kilograms OF petroleum. or 230 cubic metres
OF illuminating gas Pho cost OF first in
staliation 10 comparatively low. and. more
over. the use of such lamps obviates danger
from fire They burn forty grams. or 0.009
pounds OF magnesium per hour. and, with tho
magnesium costing fifty francs per kilogram.
the hourly expense is about two francs But
have recently been brought to notice the cost
OF aluminium production Will doubtless be SO
such lamp more than experimental.
The want OF sufficient strength to withstand
pressure. resulting in boiler explosions, is q
fact to which considerable attention has re-
Gently been directed. and. though it Is ad-
mitted that the lack OF strength may be In
herent in the original construction. the opinion
is expressed that 1t Is most frequently the
effect OF weakening Of the iron by strains
due to unequal expansion: the cause Of such
unequal expansions. and also OF weakening by
burning and blistering the iron. is usually
the presence Of deposit or scale on the heat
Ing surface. It Is estimated. by engineering
nuth ority, that the presence OF one sxteenth
men OF scale causes loss OF thirteen
Of Of and 1t
half inch involves loss OF 60 per cent. Of fuel.
kemnrking upon this. writer In an engineer,
on a locomotive in. the Middle and Western
states has, by careful estimation. bcen found
the same power In stationary boilers about
the same am cunt this extra expenditure duo
to incrustation alone.
Remarking upon the various processes now
resorted to for sizing paper. the Scientific
American notes the advantage OF using alumni
nate OF soda for saponifying the rosin used
for size instead OF soda ash or caustic soda. as
duo to the fact that In filing the paper. its
alumina serves the purpose represented by
the alumina OF the alum generally used. rem
derinc 1t practicable to dispense with alum
entirely. and. In the case of its uso together
with the illuminate OF soda. giving an excess
Of alumina, which IL a valuable addition to
tho pulp at his stage OF It's MANUFACTURES
Tho further advantage, too. oi using soluble
salts OF magnssin and cnlciHm. instead OF
alum. TO docomposo the losin soap. Is tha3
these salts are neutral. while, alum is acid
they are also cheaper than alum. aud. In tho
4 new method Of prccipiatins aiu,nina ii ' tic
this process and con ssts in aiding aluninatn
OF soda to tho san"naceous solution OF rosin
HlStu Win pup. toPother Win tne. sulphate
or chloride OF mngnesia. the chloride NJ cal
ciun. or the sulphute Of aluminl. used to pre-
cipitate the tosin from, the soap and form with
1t the sizing compound.
Some interesting facts. though Of a tochni-
cal character. are given 10y NJ. Moyrot in the
IeirtTi|r Prntique on tho chemical peculiar
tiles of silk, from which 1t appears that,
though the material. AS 1t comes into conf
merce contains from 8 to Is per cent OF
moisture. 1t Is capable of taking M much
more than this amount. fact Of which due
advantage IL taken. That IL. the usual amount
which Is recognized In all sales Of six is IL
TO contain less than that. the price Is pro.
portionntely increased. and, on the other
hand. II IT contain more. II Is reduced.
which silk contains-usually from 0.b4 o O.S0
per cent In reeled silks and about LoS In