244 
force of a column of tan-liquor, to faci- 
litate their impregnation with tan. A 
cistern or tank of tan-liquor is to be 
provided, so much elevated above the ° 
intended tanning cisterns or vats, as to 
afford a pressure of nine or ten pounds 
upon asquare inch in the bottom of the 
pipe descending therefrom. The tan- 
ning cisterns may be about five feet by 
four, and six feet deep, consisting of very 
strong and close sides and a bottom, 
and furnished with a tight lid, which, 
by means of moveable screws (of a 
well-known construction, though appa- 
rently claimed by Mr. F.) may be 
screwed fast down, and yet the lid be 
capable of being easily removed. Into 
one of the sides of the cistern, near its 
top, the descending pipe from the tan- 
cistern is to be soldered or flanged; a 
stop-cock is to be provided on this de- 
scending pipe, and a short.pipe for the 
exit of air is to be provided, and fur- 
nished with its stop-cock, near to the 
top of the tanning cistern’s side. 
The skins or hides, after being limed 
and cleansed in the ordinary way, are 
to be lapsely placed in the cistern, and 
then its lid is to be screwed on, and 
made air and water-tight. The cock for 
the exit of the air is then to be opened, 
and also the cock on the descending 
pipe: and when this last has entirely 
filled the vacuity of the cistern with 
tan-liquor, the air-cock is to be shut, 
and then the full effect of the hydro- 
static column of fluid will be exerted, to 
force the tan-liquor into the pores of 
the skins. In order to facilitate the 
tanning, the lid of the cistern must be 
removed daily, and the skins taken out 
and hungto drain, before returning them 
to the cistern, and turning upon them 
the column of tan-liquor, as already de- 
scribed ; towards the latter part of the 
process of tanning, the strength of the 
tan-liquor should be increased. 
Instead of having recourse to an ele- 
vated cistern to produce the requisite 
pressure on the. skins,, Mr, Fletcher 
claims, under this. patent, to effect the 
same, after the cistern’s lid has been 
tightly screwed on, by forcing in air with 
a condensing pump, to press on the sur- 
face of the tan-liquor in contact) with 
the skins, 
Before the first of these patents had 
been specified, and when it had merely 
been mentioned in the newpapers that 
Mr. Spilsbury used pressure in aid.of his 
new tanning process, the Writer, in p..593 
of vol, 56, took occasion to throw out a 
Patents for Mechanical and Chemical Inventions. 
[Ocr. 1, 
suggestion, as to applying pressure for 
expelling the spent tan-liquor from the 
pores of the skins, different from either 
of the modes above described. The same 
mode had then lately been successfully 
applied in dyeing, to expel the spent 
dye; and his reason for publishing the 
suggestion was, to prevent. the same 
being locked up: from general use by 
the public, in a patent. Mr. Spilsbury 
would have been well entitled, had he 
chosen to ayail himself of it, to four- 
teen years’ benefit of all the possible 
ways of carrying his principle into 
effect; but not having done so, he 
should, we conceive, be held as hav- 
ing given up to the public, the several 
modes or processes different from his 
own, 
Here we cannot avoid remarking, 
that the practice established in apply- 
ing for and obtaining patents from the 
crown, and the state of the law which 
sanctions the monopolies thereby cre- 
ated, strongly, yet improperly, operate 
upon inventors, to induce them to be 
as general and as little explicit as pos- 
sible in the titles under which they ap- 
ply for patents ; and hence our remark 
at the head of this article, that the pub- 
lic are little interested in the announce- 
ments of new patents, prior to their — 
haying received definite and unalterable 
forms, in the enrolled specifications, 
A considerable proportion of the pa- 
tentees, including mostly those who 
claim monopolies in things. of trivial 
value, and often in such as are of no 
importance whatever to the public, have 
been wont, in crying up their inven- 
tions in puffing advertisements and 
hand-bills, to try to. make it be be- 
lieved, that the novelty and merits of 
their invention had been canvassed and 
fully approved by the crown, or its offi- 
cers, prior to the patent being granted 
to them: and that the grant had been 
made, in special reward to them for 
their ingenuity, and for the importance 
of their discoveries : than which, nothing 
can be further from the truth; because, 
except when, in consequence of a caveat, 
another person possessing, or alleging 
to intend applying for a patent, on the 
same subject, appears before the Attor- 
ney General, and claims his exparte and 
secret investigation of two contempo- 
rary inventions, so far only as to, enable 
him to report, whether such, are. the 
same or different inventions, and whe- 
ther one or two patents may issue (and 
almost invariably the latter is the issue), 
there 
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