of forty tons, whereupon the safety-valve
of the large pump opens, and is kept so by a spring. While this
operation is going on, the attendant is occupied with filling the second
press; which completed, he opens the communication between the large
pump and the second press, taking care first to replace the
safety-valve. The ram of this press is then raised to the same height as
the other, after which the safety-valve rises a second time. The
attendant, as he closes the valve which opens the communication between
the large pump and the press, at the same time opens the valve between
the small pumps and the presses; and the pressure, amounting to about
300 tons, exerted by the small pump, is allowed to remain on the rams
for about seven minutes. From which it appears that, allowing three
minutes for emptying and charging the press, the process of expressing
the oil takes only three minutes in all; and it is done by this press in
this brief time in the most effectual manner. The oil, as it is
expressed, passes through the canvas and hair bags to a cistern, known
as the spill-tank, which is just large enough to contain the produce of
one day's working. The presses are worked by oil instead of water, as it
keeps both presses and pumps in better order. Each of them will produce
36 cwts. of cake per day of eleven hours, while the yield of oil is
about 14 cwts. The oil is pumped from the spill-tanks to larger ones,
capable of holding from 25 to 100 tons, where it remains for some time
in order to settle previously to being brought to the market.

I do not intend to enter into the relative merits of the various
presses, but content myself with having explained to you the manner in
which the oil is produced.

Before concluding, it may be interesting to give you some idea of the
vast extent of this manufacture. It appears, according to the official
returns, that in the year 1841 we imported 364,000 quarters of seed.

THE OIL FROM LINSEED.

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| 1842 | 368,000 | 1847 | 439,000 | 1852 | 800,000 |
| 1843 | 470,000 | 1848 | 799,000 | 1853 | 1,000,000 |
| 1844 | 616,000 | 1849 | 626,000 | 1854 | 828,000 |
| 1845 | 666,000 | 1850 | 668,000 | 1855 | 757,000 |
| 1846 | 506,000 | 1851 | 630,000 | 1856 | 1,100,000 |
______________________________________________________

Now if we take the last year's imports, we shall find that the produce
would amount to