IMPROVEMENTS IN DESICCATING AND IN PRESERVING MATTERS FROM DECAY
Year: 1863

page_text: PROVISIONAL SPECIFICATION left by William Clark at the Office of
the Commissioners of Patents, with his Petition, on the 21st January
1863. A communication from abroad by Jean Baptiste Pierre
Camille Bergouhnioux, of 29, Boulevart St. Martin, Paris, Gentleman.
I, WILLIAM CLARK, of 53, Chancery Lane, in the County of Middlesex,
Engineer and Patent Agent, do hereby declare the nature of the said
Invention for "IMPROVEMENTS IN DESICCATING AND IN PRESERVING MATTERS
FROM DECAY," to be as follows:-
This Invention consists in the numerous applications herein-after described
and hitherto unknown, which I have imagined, maintaining at all times the
following conditions:-In a space as limited and closed as possible, either
free from or filled with any gas at any tension, and any temperature,
there exists a definite or more or less indefinite source of vapor. In contact
with this vapor is a chemical or physical agent, which incessantly in either
condensing that vapor or decomposing it on the very spot, or presenting to
it always on the same spot a combination which it embraces with avidity,
has for final result either a diminution or even an annihilation of the tension
of that vapor.
I will presently describe and exemplify some of the hitherto unknown
applications I have conceived, yet not departing in the least from the above
conditions. Supposing I have to dry some damp substances, such as wood
for building, naval, or other industrial purposes, or wool, cloth, linen, paper,
ribbands, corn, medical plants, and so forth, I enclose the substances to be

page_text: dried in a space as limited and closed as possible free from any gas or air, in
this space
I introduce a sufficient quantity of a chemical agent for which
water steam has great affinity, caustic potash for instance. If steam has great
affinity for the chosen body, or if the contact surfaces are well spread and
renewed I obtain the desired desiccation. Supposing that I desire to preserve
certain substances such as corn, flour, fruits, preserved sweetmeats, or other
nutritive substances, matches, tobacco, and other hygrometric matters liable
to be injured by an excess of dampness, I enclose such substances in a space
limited and closed, in which space either free from or full of air, or of any
gas at a suitable tension or temperature according to the article to be operated
on, I dispose a chemical agent more hygrometric than the substance to be
preserved, and if the absorbing body is too hygrometric desiccation will be
effected, but there will also result the necessary preservation if the chosen
body is but sufficiently hygrometric. Now this expression "free from any
gas "must be well understood, for if it be not sufficient in order to preserve
certain peculiar substances to enclose them in a gaseous atmosphere sufficiently
unhydrated, it is further necessary that the gaseous bath be sometimes air,
sometimes azote, and sometimes hydrogen, or others, and it must be considered
as free from any gas. Supposing I have to suppress in a hot fruit house the
moisture which darkens and drops from the panes on the precious plants in
this fruit house, which in this case forms the space as limited and closed as
possible, before mentioned, I dispose a refrigerating surface colder than the
glass and frame, whatever may be the fall of the external temperature or
the rise and fall of the internal temperature it is only on the coldest
surface that the moisture will appear, and should this condensing surface
be so disposed that condensed water may be easily collected then I have
obtained the solution of my problem, and therefore the expression physical
agent, whereby the vapor can be condensed will be easily understood. Sup-
posing I have to inhabit damp premises, a cellar or otherwise, underground,
for instance, (the space being as limited and closed as possible,) I close air-
tight the door and windows, then under my bed or upon any furniture I spread
upon a tea board, or in a number of plates a sufficient surface of a substance
having a sufficient affinity. for water, chloride of zinc for instance, and
I awake next morning without a cold or a rheumatism. Now. it is thereby
evidently. demonstrated that the source may be more or less indefinite, for in
the last instance this source is no other but the very walls and sides of the
space, and there is great probability that the supply of chloride of zinc should
be nearly renewed every night. Supposing now that I wish to dry the upper
story of my own house, when scarcely finished, here again the same solution,

page_text: but the source is definite, if I have the first day collected five gallons of liquid,
next day I shall have less, and no water at all after a certain period.
Supposing that I have used ether to dissolve tannin, and wish without heating
to separate these two bodies the conditions are the same, the space will be
composed of two crucibles disposed neck to neck and carefully luted, the
crucible shall contain the solution and shall be sufficiently cool so that the
whole ether vaporizing in the one crucible may be condensed in the other
crucible. Supposing, finally, that I have dissolved india-rubber or caoutchouc
in essence of turpentine, and that without heating or ventilating I wish to
insulate, this caoutchouc in the space limited, and closed as above, I can
destroy the vapor from essence of turpentine by decomposing its very elements
either by combustion or chemical agency.
I trust that I have by the above various examples justified all the conditions
in which I have bound myself, and which limit the Invention, for which I
desire to obtain Letters Patent, my explanations will I believe enable any
industrial person to make use of and perform my Invention when the same
has become public property, but I will further treat of some peculiar points
which may be further improved.
1st, when I use chemical agents having great affinity for vapour, this having
no real value, and the chemical agent having one, I intend revivifying such
chemical agents, and restore to them as economically as possible their former
properties. For instance I dry in free air and by the cheapest vapourizing
processes chloride of zinc, which although having to day served to dry will
still serve to dry to-morrow, and this must be considered as part of my
Invention.
2ndly, in case when for saving time it should be necessary to multiply the
operations more than the extent of the space will allow, or the extent of the
surface of contact between the chemical or physical agent and vapor will
allow, some arrangements more or less ingenious may be adopted. Thus the
absorbing power of a given surface may be increased tenfold without its real
extent being varied, for instance, in the operating space where I have enclosed
milk to be evaporated I arrange bellows to circulate the air in the space,
blowing it through a cask filled with quicklime or chloride of calcium. This
air enters the cask in the damp state and goes out from it in a dry state, by
doubling the height of the cask, and the rapidity of the passage of the air, and
increasing the capacity of the bellows, I may attain the same result in a shorter
and shorter time, but this is but a corollary of my Invention.
3rdly, at any temperature and at any pressure, as stated above, the effects
shall be produced as indicated. However it will be an advantage when this

page_text: is possible to raise the temperature and diminish the pressure of the gas.
Slightly heated wood will emit, vapors in greater quantity and carbonate of
potash for a little rise in the temperature will not in consequence have less
affinity for water. At a low temperature the like effects will be produced,
but all these improvements are but mere details, the observance or non-
observance of which will be no deviation from the very principle of my
Invention.