stuff is worked for one to two hours in a bath
consisting of about 26 gallons sulphuric acid, of 3 deg. to 6 deg., 1 lb.
alum, 1/2 lb. salt, and 750 grains borax. It is then treated in a
centrifugal machine, and afterward subjected to a temperature of 212 deg.
to 248 deg.. For removal of the acid it is first washed with pure water
for 11/2 hours, then treated for two hours with fuller's earth, soda,
and lime, and finally washed for two hours with fresh water. As
sulphuric acid can only be employed with uncolored cloths, or such as
have been dyed with indigo, chloride of zinc and chloride of manganese
diluted to 6 deg. are substituted with fabrics otherwise dyed.

* * * * *

CAFFEONE.

Caffeone, the aromatic principle of coffee, may be isolated by
distilling 5 or 6 lbs. roasted coffee with water, agitating the
aqueous distillate with ether, and afterwards evaporating the ether.
It is a brown oil, heavier than water, in which it is only very
slightly soluble. An almost imponderable quantity of this essential
oil will suffice to aromatize a gallon of water.

* * * * *

THE HEMI-PLUNGER.

The novel form of vessel, to which the above odd name has been given
by its inventor, M. Donato Tommasi, of Paris, France, is a combination
of a boat wholly submerged with a raft: a connecting link, to borrow
the naturalist's expression, between the submerged torpedo boat and
the monitor. The advantages which are expected to be realized from
this hybrid craft, the inventor describes as follows: "It is evident
that a vessel, plunged several yards below the surface of the sea, is
no longer influenced by wind or wave. Let the sea be agitated, let
there be the most violent tempest, yet the boat which navigates under
water will never be wrecked, for the same reason that a fish cannot be
drowned. * * * What a beautiful vision, that of traversing the ocean,
as a balloon floats through the air, with the same tranquillity,
without shocks, without the insupportable rolling and pitching!" etc.
The construction of the invention introduced in this glowing manner
will be understood from Figs. 1 and 2. A is the plunger cylinder,
shown with its side broken away in Fig. 2. In Fig. 1, G is the rudder,
H the propeller, and I the tube through which sea water passes to the
pump. In Fig. 2, C is the smokestack, M M are compartments in which
water may be admitted to increase the weig