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IMPROVED FILTERING APPARATUS. for which we rank the higbest in the inelancholy hours to which every universe. Take the steam-engine for mortal is liable, and at some time or an example : without that pride of other must experience. It forms one British industry, where would be our of the most solid pillars of human inanufactories and commerce? How happiness, and contributes as much should we be able to compete with to virtue as to rational amusement. our neighbours in the cheapness of merchandise and the beauty of workmanship? Let only these things be DISTILLATION OF SEA WATER. well considered, and I think every

The distillation of palatable water one will, with me, exclaim

at sea has been effected by P. Ni“ Philosophia mater ompium bonarum cole, of Dieppe, by simply causing artium est.

the steam arising from boiling sea In conclusion I have only to re- water, in a still, to pass through a mark, that, “next to religion,” I stratum of coarsely powdered eharconsider science the best and sweet- coal, in its way to the condenser, or est source of recreation in those worin tub.

MP R O V E D FILTERING APPARATU S.

Cistern

Sır,-) think your « Improved F; a false bottom, to receive the Filtering Apparatus," in Number 86, water from the ball-cock, E, and to · may be reduced to one cask, by in- supply the tube, CC.** troducing through its centre a tube,

CC is the tube through which the to convey the water from the cistern

water from the cistern, W, is to pass to

the bottom of the cask. S to the bottom of the cask.

it lui

BB, the space to receive the water Youappear to have no means by from the tube, CC.” which to carry off the * aqueous åbo !, the false buttom, as you represent. mination that must remain at the five inches from the real bottom. Thiby bottom of the cask: I think the fol. G, a cock to discharge the impure

water. 1szins i Syuló

* A, a cock to discharge the pure water. your plan. ve 9 r . .

The water should all be discharged,

G. C. and the cocks left open during one Manchester, April 20, 1825. ve

night in the week. viit! ' Description. ill.,

· It is not necessary to have a vessel

to retain the pure water, as the quantity E, a ball-cock, to regulate the filling

discharged by the cock, A, will be raof the cask from the cistern, W. pidly replaced. .

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SIR, If you consider the above inven- bells, it gives the advantage, by a retion of mine, for conveying telegraphic ference to the index, of telling the intelligence, worthy a place in your use- servants what is wanted, the graduate ful Magazine, your speedy insertion of scale being marked with such things the same will give me much gratifica- as are usually wanted in a house. tion. If I am not too sanguine, this ap- . This contrivance would be found of 'paratus, if carried into effect,would con- great advantage in cases of fire. Let vey intelligence to the remotest parts there be one station in every parish, of England by the darkest night as with pipes leading from thence to every well as by the brightest day, and an- engine-house in the metropolis. At swers would be returned with nearly the moment the men bear the alarm'the same facility and precision as two whistle at the engine-houses, let them persons van question and answer each shut the cocks and look to the index, other, sitting in the same apartment and the point where the fluid or index It is also suited to domestic use, for, rests will mark the parish the fire is besides answering all the purposes of in. Let them make another move at 282

CALCULATING WEIGHT OF ÍRON PLATES. the parish station, and the place where of pumping air into the tube,SSS,in Lon. it settles the second time will point out don, it must be exhausted from it, which, the street. As all the persons on the rarelying the air within the air tubes,

SSS, the atmospheric pressure will act different stations will receive notice at

upon the fluid in glass tubes, and will the same moment, the engines may be

cause it to sink in proportion to the directed immediately to converge to quantity of air exhausted, viz. from the spot.

30 to 0 (in both places at the same I am, Sir,

instant), or any point between the two. Your obedient servant,

If intelligence is to be conveyed

from Portsmouth to London, what is JAMES BUTTEBS.

directed to be done in London must be 36,Wigmore-street, Cavendish-square, done at Portsmouth.

July 6th, 1825.
Description of the Drawing.
BB are two graduated glass tubes,

CALCULATING WEIGHT OF IROY the one at London and the other at

PLATES. Portsmouth, charged with rinted oil. Sir, - Being constantly employed SSS, a metallic tube which connects

etallic tube which connects among iron plates, range backs, &c. the two glass tubes, and extends from and having frequently occasion to London to Portsmouth. It is proposed

weigh them when I want only a rough to lay it eight feet beneath the surface

calculation of the weight, I was inof the earth, where the temperature is

duced, in order to save trouble, to use always the same, so that no expansion

the following manner of calculation,

which I generally find comes very near or contraction of pipes can take place.

the real weight, frequeutly within a CC, air-cocks, with wbistles to give pound of it. alarm.

EXAMPLE. PP, pumps for condensing or rarefy

Suppose I want to find the weight ing air in the air tubes.

of a cast plate which measures 32 The upper dotted line shows the iuches long, 20 inches wide, and 1 inch height or level at which the tinted oil thick. I first multiply the length and will stand hoth at London and Ports. breadth together, which gives me the mouth, when the apparatus is not at number of square inches contained ; work--the lower dotted line, the surface I then divide by 4, supposing four of the earth.

square inches of cast iron to be equal Having described the different parts to one pound-this gives me the weight of the apparatus, it will only be neces- in pounds; I then divide by 112, 28, sary for me to explain the manner of and 4, which brings it into ewts., as working it. Both the alarm-cocks, under :with the whistles, must always be open when the apparatus is not at work.

Suppose we want to make a communication from London to Portsmouth,

4) 640 .t's u shut the alarm-cock in London, and pump air into the tube SSS, and the

112) 160 (1 cwt. air injected will drive the air in the

, 1761 tube wder ground to Portsmouth, when it will escape through the cock there and make a lond whistle ; the

28) 48 (l quarter. 15 man, upon hearing it, will immediately

28 . shut the cock, and the compressed air not being able to escape, will press

20 lbs. upon the Auid in tubes BB in both places, and raise it from 30 to 60 in the graduated glass columns, or any By so calculating I find the weight point between the two. The figures or is 1 cwt. I quarter, 20 lbs. If the plate characters on the corresponding gra is one inch and a half thick, I proceed duated scales may represent letters, in the above manner, and after I have words, or sentences, as may be agreed divided it by 4, which brings it into upon. . When the characters or figures pounds, I then add the half of it, then to be pointed to stand below 30, instead divide it by 112, &c.; but, if it is two

32

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USES OF SALT IN, MANUFACTURES AND AGRICULTURE. 283 inches thick, I divide the square inches laid on the article manufactured, since, by 2 instead of 4, and so on according however, remitted. to thickness.

| Epsom salt is prodiiced entirely from in 1, 1 am, Sir, ... . . . salt, or the evaporation of sea water. Los Your obedient servant, on The brine, which yields 100 tons of * Norwich.

J. W. G. salt, gives from four to five tons of

this valuable article. Dr. Henry,

the celebrated chemist of Manchester, · [We shall be glad to receive 'our has discovered a process of preparing Correspondents' « similar calculations it from magnesian limestone, and has as to cound and flat bars, jack weights, reduced the price one-half. It can round balls,” &c.; not that we think be made still cheaper from sea water, them so deserving of adoption, as that for the employment of which a duty they may lead to the communication is laid. of some other modes equally simple

Magnesia is made from salt brine, and still more exact.-EDIT.]

or sea water. The English duties are so high as to render it probable that both this and the preceding article will,

in future, be obtained by Henry's prouses'OF SALT IN MANUFACTURES

cess from magnesian limestone. AND AGRICULTURE. '

Crystallized soda is also made from Important advantages are now de

common salt; aud if the latter, or sea rivable from salt, since it can be water, could be obtained free of duty procured without duty., In a work in England, it would supersede tbe impublished at New York, by Dr. Rens portation of American or Russian pot selaer, some of the purposes to which and pearl ashes, and 10,000 tons would salt may be applied are thus de- be used annually, several hundred tons scribed :

in washing alone. Sal ammoniac, pr muriate of ammo Barylla, of an excellent quality, is nia, is made in abundance from con- made froni salt. mon 'salt. The manufacture of this

In the manufacture of hard soap salt article was abandoned in England, in

is a necessary ingredient. consequence of the heavy duty of 301. per ton laid'on salt. In consequence, Corrosive sublimate is always made however, of bittern, from the salt works, from common, salt. . being allowed in Scotland for the ma Patent yellow is also prepared from nufacture, the price has been reduced common salt. nearly one-half.

In the Fisheries, in salting provisions In the manufacture of glass, salt is for the sea service and for exportation, largely employed : soda, which is pro

salt is largely employed.
salt is largely

'
cured from common salt, is used for
plate-glass; potash, for flint-glass; and

Butchers, morocco dressers, and skincommon salt, with kelp, for crown- ners, employ it in large quantities. glass.

Dr. Rensselaer here calculates that, Oxymuriate of lime, and other oxy

in England, three times the present muriatic salts employed in bleaching,

quantity would have been eaten if are made from salt, and consume a

there had been no duty] large quantity of it in the manufac Farmers use great quantities in ture.

making butter and cheese, and for Spirit of salt, or muriatic acid, re- steeping wheat to prevent smut. quires large quantities of salt : at least In glazing earthenware much salt is 1000 tons are used for this purpose in consumed, and is far preferable to the England every year, notwithstanding preparations of lead, which are liable the enormous duty. It is used in a to he dissolved by vinegar and eateu, variety of processes in dyeing and In England the manufacturers of earthcalico-printing

en ware sometimes pay unc-twelfth of BilGlauben's salt is made from what of the real amount of their sales for remains in the stills after the distil. salt. ' lation of muriatic acid. This residuum Salt is likewise employed by ironwas formerly thrown away, until a per- founders in metallic cements, and in son employed it in making Glauber's rendering har iron very malleable. It salt, when a duty of 301. per ton was is used by whitesmiths and cutlers in

salt.

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284

PROTECTION OF COPPER SHEATHING. case-hardening, in tempering files and of that metal to become covered with some other edge-tools; mixed with other weeds and shell fish, except in cases substances, for reducing metallic ores, of rapid motion, such as in steam

boats, where the chemical action of fusible, by the refiners of silver, and to prevent the oxidizement of some

sea water upon copper may be enmetals. It is used to moderate the

tirely prevented without the possibiflame of combustible bodies, and is

lity of the copper becoming foul. extensively employed by the philoso The President describes a number phicaland manufacturing cheinist, and of experiments, which show that the by the druggist for a variety of phar. most rapid motion does not interfere maceutical purposes.

with the principle of protection. He In horticulture salt is much used, ascribes the relations of this proparticularly in England, where its perty of electro-chemical agency to merits are better appreciated than with the conducting powers of metals and us. It prevents the depredations of of fluid conductors ; and he shows insects on fruit trees, and, when pro- that a certain contact with fluid conperly applied, protects them from the

ductors, even upon a small scale, is honeydew. Persons ambitious of having good cider vrcbards should dig

sufficient to enable oxidable metals a small trench a few yards from each

to preserve more difficultly oxidable tree, and place within it a few pounds metals, and that slight chemical of salt, which by the rains is gradually changes are sufficient for the effect. conveyed to the roots, and produces Iron in a solution of brine which most desirable effects.

contains no air is very slowly acted upon, and yet iron in brine in one cup will preserve copper in sea water

in another cup, provided they are PROTECTION OF COPPERSHEATHING.

connected by a moist thread of cotton. 7 At a recent meeting of the Royal He points out the limits to this kind Society, there were read, “ Further of action, and illustrates it by a very Researches on the Preservation of curious experiment. If of two vessels Metals by Electro-chemical Combi- containing salt and water connected nations; by Sir Humphry Davy.by moist cotton, and forming an

In this paper Sir H. Davy enters electro-chemical series by means of into a minute detail of the causes zinc and iron, a few drops of solution which operate in producing foulness, of potash or soda be poured into as it is called, or the adhesion of that containing the iron, the action weeds and shell-fish to the copper of of the iron on the sea water will be ships. This he attributes to a crust diminished, but the copper will still of carbonate and submuriate of cop- be protected; but if the solution per, and carbonate of lime and mag- containing the iron be made alkaline nesia, which gradually fix upon the to any extent, the copper will begin sheathing, and which, by rendering to corrode, and the iron will become the copper in the surrounding parts the electro-negative metal. positive, occasions its corrosion, so Sir Humphry ends this paper by that ships are sometimes found, in the inportant practical conclusion, the common course of wear, foul in that copper may be preserved by some parts, and the copper worn in nails, or masses of zinc oriron placed holes in other parts.

zender the sheathing, and that, in this He conceives that proper protec. way, there is less loss of the oxidable tion, if not in excess, by producing metal, which is partly revived upon a similarity of electrical state, or of the interior of the copper, so that disposition to chemical change in the saine metal will açt for a long every part of the copper, 'will pre- time; and thus protectors may be vent the rapidity of its wear without applied to save the whole or any giving it any disposition to foulness; portion of the copper without interbut if iron or zinc are used in such fering with the external surface of ii, quantities as to save all the copper, and without the deposition of any then they will increase the disposition matter likely to cause adhesion,

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