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dluding, however, from consideration mere mountain bogs, and also all bogs of less extent than 500 acres, of each of which description the amount is very considerable; of the extent of the latter some idea may be formed from The commissioners then proceed to a fact state the particulars of their Larkin that to Cavan, which he has surveyed, there are above 90 bogs, no one of which exceeds 500 Irish acres, but which taken collectively contain about 11,000 Irish, which is equivalent to above 17,600 English acres, besides many smaller bogs varying in size from five to twenty acres.

considerable obstacles to improvement, the overcoming of which would in itself demonstrate the practicability of the improvement of the bogs of Ireland in most other cases."

in the single county of out the bogs to be surveyed,celling

are

Most of the bogs, which lie to the eastward of the Shannon, and which occupy a considerable portion of the King's county and county of Kildare, generally known by the name of the Bog of Allen: it must not how ever be supposed that this name is applied to any one great morass: on the contrary, the bogs to which it is applied are perfectly distinct from each other, often separated by high ridges of dry country, and inclining towards different rivers, as their natural directions for drainage, so intersected by dry and cultivated land, that it may be affirmed generally, there is no spot of these bogs, to the eastward of the Shannon, so much as two Irish miles distant from the upland and cultivated districts.

With this first and general view of the subject, we had no hesitation in se lecting at once the whole of the eastern portion of the great district above referred to, as the object of our first enquiries, forming in itself one whole, whose parts had more or less connection with each other, lying in the centre of Ireland, in the immediate vicinity of some of the richest and best cultivated counties; intersected also by the two great lines of navigation, the Grand and the Royal canals, and presenting in common apprehension very,

ent engineers, with the pay allotted to them and the persons employed under them; and they then give some observations derived from the first report delivered in, that of Mr Griffith, to whom was consigned a district forming the eastern end of the Bog of Allen, and containing 36,430 English acres of bog. Of these we shall transcribe some of the most instructive.

"There are many, we believe, who consider the bogs of Ireland to be low and marshy tracts of country, not very dissimilar in their composition from the fens of Lincolnshire; others, aware that the substance of which they are formed greatly differs from that of the fen districts, attribute nevertheless the origin of both to pretty nearly the same causes; while an opinion, more preva lent, and perhaps not less erroneous, than either of the foregoing, attributes. their formation to fallen forests, which are supposed at some former period to have covered these districts, and to have been destroyed either by the effects of time, or by hostile armies in the early wars of Ireland.

"The facts stated in Mr Griffith's report are obviously inconsistent with any of these suppositions ic the bogs which he has surveyed being every where in elevated situations; and the trees which have hitherto been so constantly found buried in the edges of these bogs, where alone it is probable they have generally been sought for, are very rarely to be found in the inte rior parts, at least of this s district, 1939

"Without entering in this report into any enquiry as to the origin of these peat bogs, we are however anxious to

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such persons as have not had an
give
Opportunity of examining them, some
idea of the general appearances which
they actually present.

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ness from one to six feet ;
places the peat rests on a thinner stra-
tum of yellowish white marl, contain-
ing upon an average about 60 per cent.
of calcarious matter. This stratum
of clay in this district universally rests
on a solid mass of clay and limestone
gravel mixed together, and extending
to an unknown depth.

"We should further consider the peat
moss as partaking in its general nature
of the property of sponge, completely
saturated with water, and giving rise
to different streams and rivers for the
discharge of the surplus waters which
These
it receives from rain or snow.
streams in this district almost universally
have worn their channels through the
substance of the bog down to the clay
or limestone gravel underneath, divi-
ding the bog into distinct masses, a
presenting in themselves the most pro-
per situations for the main drains, and
which, with the assistance of art, may
be rendered effectual for that purpose.
"Such is the internal structure of
4 193
the bogs in this district.

and

"It appears from Mr Griffith, that each of the four bogs included in the subject of his report, is a mass of the peculiar substance called peat, of the thickness of 25 feet, no where average less than 1 12, nor found to exceed 42; this substance varying materially in its appearance and properties, in proportion to the depth at which it lies; on the surface, covered with moss upper of various species, and to the depth of about ten feet composed of a mass of the fibres of different vegetables in different stages of decomposition proportioned to their depth from the surface, generally, however, too open in their texture to be applied to the purposes of fuel below this, generally lies a light blackish-brown turf, containing the fibres of moss still visible, though not perfect, and extending to a further depth of perhaps ten feet under this. In the instance exhibited in the section at the close of Mr Griffith's re- "Viewing them externally they preport, are found small branches and sent surfaces by no means level, but twigs of alder and birch; but we do with planes of inclinations amply suf not understand him as being of opi- ficient for their drainage. The highnion that such is by any means ge- est summit of any part of the bogs in nerally the case. At a greater depth this district is 298 feet above the level the fibres of vegetable matter cease to of the sea, taken at an ordinary springbe visible, the colour of the turf be- tide in the bay of Dublin; while the comes blacker, and the substance much lowest point any where on their sur more compact, its properties as fuel face is 84 feet lower than the highest, more valuable, and gradually increa- and therefore 214 feet above the level sing in the degree of blackness and com- of the sea. It requires a mere inspecpactness proportionate to its depth. tion of the map and sections to be Near the bottom of the bog it forms convinced that there is no part of these a black mass, which, when dry, has a bogs from which the water may no strong resemblance to pitch, or bitu- be discharged into rivers in their imminous coal, and having a conchoidal mediate vicinity, and with falls adecture in every direction, with a quate to their drainage; e and we ob. black shining lustre, and susceptible serve, in the instance of the bog of of receiving a considerable polish. Im Timahoe, that a part of its water is mediately below this lower stratum discharged into the sea at Drogheda, there is generally found a thin stratum and another part below Waterford.” of yellow or blue clay, varying in thick.

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The art of discharging writing is very ancient, and the means employed are very simple. In fact, we know that it is sufficient to moisten a writ. ten paper with any acid, when the writing will gradually disappear. But all the acids cannot be employed with equal success. Some leave a stain on the paper, which is not easily removed; others corrode, and render the paper unserviceable. The way to avoid these inconveniences is to make choice of an acid which shall act on the writing only, without injuring the paper, or or - a colour different from that giving which it had before it was written upon.

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In order to discover such of the acids as are best suited for the operation in question, the author determined to submit common writing ink to the action of different acids, and to observe carefully the phænomena which these bodies present at the time of their mixture. According to him, the sul. phuric acid easily takes out writing, phuthe out at the same time it gives an oily tint to the paper.

The acid oxalate of potash produces

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It is not the same case with the nitric acid, which always takes out the ink, but soon penetrates the paper, and forms above it undulated lines of a yellow colour.

We may succeed, however, in softening both these effects, by taking the precaution to dilute the nitric acid with a sufficient quantity of water, or to wash the paper immediately after the writing has been taken out.

A mixture of the muriatic and nitric acids has but a slow action upon writing. It bleaches the paper, and does not oppose its desiccation," when we employ the nitric acid alone.

In general, whatever be the kind of acid employed to discharge writing, it is always proper, when the operation is performed, to dip the paper in water, in order to dissolve the new combina tions which the acids have formed with the particles of ink which have been discharged.

Mr Tarry, at the conclusion of this article, does not fail to observe, that China ink does not act like common ink with the acids, as its composition is quite different from that which we use for writing of all kinds. So far from the acids attacking China ink, they make it, on the contrary, of a deep black: it cannot be discharged therefore without erasing it.

ARTICLE II.

Processes for ascertaining what Writing has been substituted for something taken out, and Methods of reviving the Writing which has disappeared.

All the methods which have been 10

given for discharging writing consist, as abovementioned, in decomposing the ink, and in forcing its constituent parts to form other combinations. These combinations, being decomposed in their turn by different agents, may regain a tint, which, if it be not that of ink, at least exhibits a shade which becomes perceptible enough for ascertaining the letters and words which had been traced on the paper before it was touched by the acids.

The gallic acid is, according to the author, one of those agents, which in this case succeeds very well.

The liquid prussiate of lime also produces a good effect.

It is the same case with the alkaline hydrogenated sulphurets. But it is very certain that we never obtain any success from the employment of these agents, when we have left any acid long in contact with the writing, and particularly if we have washed the paper afterwards.

In short, we may easily conceive, that in this case the constituent parts of the ink which were combined with the acid, and had formed with it compounds soluble in water, having been taken up by this fluid, ought not to leave any trace of their existence longer; and consequently it is impossible that the agents employed for discovering them can render them visible.

It is also for this reason that the gallic acid, the liquid prussiate of lime, the alkaline hydrogenated sulphurets, and so many other re-agents which have been so much praised, can no longer be regarded as infallible methods for reviving writing.

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destroyed; others imperceptibly lose their black colour, and assume a yel low one; several, after a length of time, enter into the paper and spoil it; lastly, there are some which are first pale, and them become very black.

All these differences arise from the nature of the substances which have been employed in the making of the ink.

Convinced of the advantage of having a good article of this kind, the author commenced a series of experiments, but is forced to admit that he has not discovered any recipe superior to that which has been published by Lewis. This ink, according to our author, combines every advantage; but we must observe, that it is no more exempt than the rest from being dissolved in the acids, and in this respect it has an inconvenience which those who wish to discharge writing from paper know very well how to profit by. This circumstance, no doubt, induced M. Tarry to make some new experiments, in order to obtain an ink which should be unalterable by chemical agents; and he appears to us to have succeeded in his object.

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ink. The oxymuriatic acid makes it assume the colour of pigeons' dung. After the action of this last acid, the caustic alkaline solutions reduce it to the colour of carburet of iron; the characters of the writing nevertheless remain without alteration, and it cannot pass through these different states, except after long macerations. The principles of which it is composed render it incorruptable, and it can retain its properties many years."

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The results which we obtained coincided entirely with those of the author, and we have so hesitation in saying, that his is the best we have ever seen of the kind which is called indelible ink. It is liable, however, to deposit a sediment, a disadvantage which we think might be removed by M. Tarry after a few experiments. We have tried to discharge it with all the known chemical agents, but without effect; and we think the inventor deserves the thanks of the Institute, and of the community at large..

ON THE CULTIVATION AND MANU-
FACTURE OF WOAD, AND ITS BE-
NEFICIAL USE COMBINED WITH IN-
DIGO. By Mr John Parrish.

From the Bath and West of England

Agricultural Society's Papers.

Woad is a plant which, combined with indigo, gives the best and most permanent blue dye hitherto discovered. It is of great importance to our coma merce, as well as to agriculture, beHsing in nature one of the best preparers of land for a corn crop that has hitherto been discovered; and, if the land is properly chosen for it, and well managed, will be found very profitable, smore particularly at this time, when its price is advanced to almost an unpreyltedented degree: therefore I conceive,

that in rendering its cultivation and preparation better known and under stood, it may be greatly beneficial to the nation.

I have the honour to be a member of the Bath and West of England Agricultural Society, where many noble and exalted characters unite their talents to promote the public benefit. And to one of its earliest and most respectable members I presume to address this information.

I have been many years a considerable consumer of woad, and have also cultivated it with much success: and though I am well experienced in the usual method of its preparation, I was induced to depart from it in consequence of the great waste of its juices in the old method of grinding and balling. But I shall endeavour to give instructions for carrying on each process, and leave those who shall undertake it to proceed as they think best.

This plant is cultivated in different parts of England for the use of the dyers, as well as in France, Germany,

&c. It is best to sow the seeds in the month of March, or early in April, if the season invite, and the soil be in condition to receive it; but it requires a deep loamy soil, and is better still with a clay bottom, such as is not subject to become dry too quickly.

It must never be flooded, but situated so as to drain its surface, that it may not be poisoned by any water stagnant upon it.

If (at any reasonable price) meadow land to break the turf can be obtained, it will be doubly productive. This land is generally freest from weeds and putrid matter, though sometimes it abounds with botts, grubs, and snails. However, it saves much expence in weeding; and judicious management will get rid of these otherwise destructive vermin. A season of warm show.

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