,a7e ig,, protected by the lines are
colored by the solution
naDer. therefore, in a
Treating the
prussiate hath
brings up the drawings iu clear, dark
blue lines on a white ground. The
sheet of reproduced drawing is well
washed in water, ami then all traces 01
the urotosalt of Iron is removed in a
bath acidulated with hydrochloric acid.
i Color may be applied to the fac-aimile
in the uual way
As an illustration of the niefeoroloical
effect of ocean currents, Mr. .J K
Lauton lately called attention in a lec
ture to some estimates made by Mr.
("roll of the heating influence of the
Gulf Stream. He calculated that the
surface water of the North Atlantic, if
deprived of the Gulf Stream, would be
, reduced to a temperature very lar ueiow
' the ireezing point, and that the heat
which this great current disperses into
the air ahove it. it c -inverted into pow
er, would be qual to the horse-power
. r
of 400 OtO.OUO oi the largest Iron-ctaa
menor-war. It is this heat w hich,
carried over the northwest of Europe,
makes there green nehls ami op. n nar
"O during the winter, while iu I.at-
.buried wUh gnow anJ the harbors
; blocked with Ice.
The most certain test tf the goodness
ber; bad iron will break like a carrot,
it snaps in two.
