Eureka daily sentinel. [volume] (Eureka, Nev.) 1871-1887, 1878-02-07
A NEW Nox.CONDUCroR.

ure Of what is termed mineral wool"
or .'sllicate coiton." II Is pro-
duced by blowing steam through
melted blast furnace Stag. The
Stag Is allowed TO flow in a
thin stream across a steam jet. and
thereby is mechanically disintegrated
and subdivided iE globuIes, the
greater part of which are drawn out in
their flight into fine vilreous threads,
which break up easily and settle on
the floor and walls OF the receiving
chamber. somewhat after the fashion
of snowflakes In a whirlwind. The
apparatus used is said to be very sim.
Pile and inexpensive in construction,
and Is located convenient to tie fur
nace. so that the Stag is utilized while
still in the molten state. We are as.
sured by the Mining and Scientific
Journal that TIE effect Of the
blast in subdividing the Stag is sur
prising. A cubic foot of Stag weighs
from 100 to 100 pounds; of No. l min
eral wool (which Is the cheapest grade),
% pouuns; of No. ., l6 pounds. and of
No. 8, only s pounds. The different
grades as above enumerated are pressed
alike, and the difference in their weight
by measurement is caused by the re
spective ~fineness of fibre, and by the
intermixture of shot, which varies in
size from l.l6 Of an inch in diameter in
the cheapest, to o dust-like sand in The
finest quality. The only ingredient in
mineral wool which is soluble through
atmospheric influences is a small per-
centage (about one per cent? of sui
phide OF lime, which usually occurs in
biast furnace Stag. and in the wool
made therefrom. When such wool is
repeatedly steamed and heated as by
leaks in steampipes, this sulphide
changes into carbonate of lime, which
makes the wool 'istick," or slightly
cement together, without, however,
diminishing its volume. so that when
the canvas or jacket is removed care
fully from a s,eam pipe the wool will
hold on by its W adhesiveEess. For
applications where this change is CON
sidered Objectionable, the wool should
be made out of acid Stag, and when TO
be used as a filter for acids, etc., it a
be easily made from high silicates.
For general purposes, however, a near
~ neutral or somewhat basic Stag
seems to answer best. On account of
the ~iooseness of mineral wool, its ap.
plication to pipes requires some device
10 stuff it around and to hold it on.
These devices are So simple that any
average mechanic could suggest a
dozen different methods at first sight.
For boilers a sheet iron jacket bent
over the boiler before the wool is
stuffed in-is undoubtedly the best
covering. as it will las, as long as the
boiler, and costs less than the brick
encasings, which, besides, occupy too
much space. A substance, to be a su-
perior non conductor for application
on heated surfaces, should combine
great air, combining capacity with indie
st~ructibility which means thatit should
contain nothing organic. To further
sub>tanliate these statements. q few
experiments have been made after the
method used by Count Rumford in
1892. The ball and stem OF a Their
mometer were covered with an inch
thickness of the substance to be tried.
by placing it within q larger bulb of
glass and then filling the surrounding
interval between the two with the sub
stance, and after healingthis apparatus
to a given degree i'm boiling water, it
was surrounded by Ice, and the COM
parative lime required to cool the
thermometer q certain number of
degrees was noted. The figures
following the names of the substances
mark the number of seconds required
respectively for coofing down the Their.
mometer through 60 degrees Fahren-
heit: asbestos, 800; cotton. 43S; felt,
463; mineral wool, TO. Mineral wool
should be applied between v aud
three inches thick. The No l quality
Is used for lining large ice-houses.
brewers vaults. ETC.. and is put on
with the hes. results. four inches thick.
1t Q cost Of 1915 cents per square foot.
A square foot OF No. 2. two inches
thick, costs 10 cents, and II of No. 8.
cost 20 cents. From these facts it is
not surprising that this new product
Is gaining rapidly in popularity as a
o conductor, and that it is being
constantly applied to new uses-for
coating steam pipes and boilers; lining
refrigerstors and ice .honses; lining the
bottoms Of evaporating pans in chem
ical works; lining houses; deafsning
walls and floors; for filters for any
kind OF liquid. and for a great variety
Of other purposes Of o similar nature.
Not only is the manufacture ofmineral