Mineral Point tribune. (Mineral Point, Wis.) 1869-1938, 1875-09-30
MECHANICAL AND SCIENTIFIC.

MECHANICAL AND SCIENTIFIC.
"A good test for gold or silver is a
piece of lunar caustic, fixed with point
ed stick of wood. Slightly wet the metal
to be tested and rub it gently with the
caustic Ii gold or silver the mark will
be faint; but if an inferior metal il will
be quite black.
To make limitation ground glass that
steam will not destroy, put piece of
putty in muslin, twist the fabric tight and
tie it into the shape of pad; well clean
the glass first, and then pat it all over
The putty will exude sufficiently through
the muslin to render the stain opaque.
Let it dry hard, and then varnish If a
pattern is required, cut it out in paper as a
stencil, place it so as not TO slip, and pro-
coed as above, removing the stencil when
finished. If there should be any obec-
ton to the existence of the clear spaces,
cover with slightly opaque varnish.-
Journal Of Chemistry.
"A new and beautiful optical instru
ment called the microscopic telescope has
been invented for the use of photogra-
piers. 1t consists of two parallel tele-
scopes about three feet in length and two
inches in aperture, connected by hinges
and separated to'the distance of the eyes
by an adjusting screw. In order to pro-
duce the effect of the microscope there are
placed before the object glass prislnatic
lenses OF about three feet focus, so that
when these lenses are in position an OBJ
iect three feet in front of the object glass
will be seen by both eyes distinctly and
magnitied according to the power of the
eye piece.
In a lecture on coal Prof Brewer
adopting the theory that the sun is the
fountain head of all force on this earth,
argues that when coal is burned we are
merely receiving the heat and light shed
by the sun on vegetation in bygone geo
logical eras, the fact being that force is
never destroyed, being simply changed
from one kind of force to another He
defines coal as a substance of vegetable
origin, made perhaps of swampy material
or of vast forests, and consisting princi.
pally of carbon, with which are united
hydrogen and oxygen, together with some
earthly matter, its hard or soft character
depending on the amount of volatile mat
ter present
The JoHUal Of the Society Of Arts OBJ
iectS to pavements of wood, because that
material is porouS--composed in fact, of
bundles of tibres-and therefore absorbs
and returns wet very freely, foul wet es.
pecially, The iibreS of the wood being
necessarily placed vertically, the uppe,
ends fray out, are abraded, become like
| painters brush stumps and are about as
permanently dirty or they break up like
the wooden handle of chisel which has
Otter been struck with an iron hammer, or
a wooden mallet when used upon an iron
| chisCl, At all times wood is wet or damp.
| more or less, except duringcontinued very
| dry weather, and its structure is such that
| ii admirably adaptS ii 10 receive and hold.
| and then to give Off in evaporation very
| foul matters, which faint the atmosphere
and consequently iniurc health Absolute
| cleanneSS and dryneSS are prime conditions
| in pavement-wood is the extreme CON
| trary of this it is necessarily dirty soon
| after use, and is almost continuously damp.
MIR. SAMUEL PLINsoLL's recent apology
| to the House OF Commons for the use of
| supplementary language recalls sim
| liar incident in the life of Lord North.
| Ii is related Of him that. in one of the de-
bates on the American war of 1882, he was
violently attacked by a member of the
| House, who called him the "Scourge OF
the country" whereupon, losing his tenn
| per for once, he was retorting that he
| had been used from that quarter TO
| language so uncivil, SO brutal he might
| say So inSoent--n when he was stopped
short and ordered omake an apology, not
! only TO the House, but TO the member per-
sonally. His Lordship replied that he
was ready to ask pardon of the House.
| but of the member never" After tn.
| multi of over three hours, however. he had
10 submit, powerful As he was, to even
| this humiliation.
THE report of the Deputy Master of the
| English Mint for the year 1874 has recent
/ ly been presented to both houses of Par.
lament Il appears that during the year
| the total coins struck numbered q i61 =.
| lie, OF the value of CASH., .S9. The gold
coinage, including both SovereignS and
| halt.soyoreigns, amounted in value to 81.
| 462 800, or considerably less than in pre-.
| Cedinc years, but TO this must be added
| nearly two millions sterling Of gold coin
ace imported from Australia
->
THEopoRs TILroN lectures before Baylie. 5
Great Mercantile College, al Keokuk Iowa,
in November. Other eminent speakers follow.