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the air is a proof, that the coffee be also tried, was of very inferior has lost some of its most volatile quality. parts; and as that liquor is found “ The common method of boile to have lost its peculiar ftavour, ing coffee in a coffee pot, is neither and also its exhilarating quality, it' economical por judicious.. A large is inferred, that both these qualities guantity of the material is wasted must undoubtedly depend on the in this method, and more than half preservation of those volatile paris of the aromatic parts, so essential which so readily escape.

to its good qualities, are lost. If the liquid were perfectly at One pound of good Mocha rest, the particles which could es- coffee, which, when properly roasted cape from its surface, would be in- and ground, weighs only fourteen comparably less in quantity, than ounces, will make, by proper mawould escape by agitation, which nagement, fifty-six full cups of the would continually present new por- very best coffee that can be made. tions of the fluid to the air. But " If it he not ground finely, the all fluids, while heating or cooling, surfaces of the particles only will by partial communication, are known be acted upon by the hot water, and to be agitated ; a fact long and well the waste will be very great, from known, but particularly explained the large proportion of coffee left and insisted upon by our author, in in the grounds. many of his valuable works, and “ The size of a coffee cup in which he again perspicuously and England usually answers to 8; cufamiliarly explains in the present bic inches, but the count considers essay. His object is to indicate the gill measure as a proper standby what means the heat of the li- ard for a cup of coffee, which he quor may be uniformly kept up in therefore adopts. This will fill the all its parts : for the consequence former cup 10 seven-eighths of its being, that the parts will, in those capacity, and quarter of an ounce' circumstances, be at rest, the mo- of ground coffee will be fully suftions by which the aromatic parts ficient to make a gill of the most might have been dissipated, will not excellent coffee. take place.

“ It is well known to chemists, " By pouring boiling water on that any solvent already in part the coffee, and surrounding the cona charged with a substance intended taioing vessel with boiling water to be taken up, will be less disposed or with the steam of boiling water than before to take up any addithe coffee itself will be kept perma- tional quantity; and upon this is nently at the same beat, and will founded the process of percolation not circulate, or be agitated. or straining, as is practised in brew

The count observes, that from ing and other arts, and has been for the well-known fact, that boiling some time recommended and used water is not the most favourable for in making coffee. To this the count extracting the saccharine parts from gives this approbation. He finds, malt in brewing, he was induced by experience, that the stratum of to try a lower temperature than the ground coffee to be laid upon a perboiling heat in making coffee; but forated metallic bottom of a vessel the coffee did not prove so good. or strainer, ought to be about twoThe cold infusion of coffee, which thirds of an inch thick, and to be

$ 2

reduced

seduced by pressure by a piston or and it would be well to have a round filat plate of metal (after levelling plate or rammer, to compress the it) to less than half an inch. From coffee on its bottom, and defend it the data he infers, by a chain of from the stream of hot water, when observations, that if the height of poured in. These several parts are a cylindrical vessel or strainer be to be dipped in boiling water before taken constantly at 5 inches, the using, and the difference between diameter of its bottom must be coffee made by this simple and To make 1 cup of coffee = 1{ inch cheap apparatus, of which the mug

2 cups = 21-3 or 4 cups = : 24 may also be applied to other uses, -5 or 6 = 31–7 or 8 = 4-9 or and that made by the most perfect 10 = 4-ll or 12 = 5.

machines, will scarcely be distin“ These strainers are to be sus- guishable. pended in their reservoirs or vessels “ Sufficient length has a!ready for containing the coffee, and the been given to our abstract, to forwhole included in another vessel bid us to follow the count in the called the boiler, which is to con- explanation of bis views directed to tain boiling water, kept hot by a the benefit of society, with relation lamp, or otherwise. The forms of to the comforts of individuals, as these are given with drawings, upon well as io the economy of the politi. which it does not seem needful to cal aggregate. That it would be enlarge in the present abridgment, preferable

to consume an article probecause there are several vessels of duced by the colonies of European this description, with the exception nations, who demand tbe manufacof the surrounding boiler, to be tures and products of the parent found in our shops.

state, instead of sending bullion to " The reader must have recourse China for an article of less value: to the essay itself for these and other that it would be preferable that the particulars of considerable interest, poor should enjoy the innocent exand delivered in the familiar and per- hilaration of coffee, and the natrispicuous style which distinguishes ment of sugar, instead of forgetting the writings of this author. The their bardships during the momen. poor, and those who prefer simpli- tary intervals of insanity, produced city of structure to the extremes of by fermented and distilled liquors ; perfection, will be gratified by a that they should be cheerful, benedescription of his last apparatus, volent, animated, healthy, and infig. 8. It is a porcelain, or earthen dustrious with coffee, instead of bejug, with a tubular spout, not un- coming outrageous, miscbievous, dislike those which we call milk jugs, eased, idle, and sunk in languor and except that these commonly bave a debility with gin, &c. &c. nese lip-spout (which would answer are among the meditations internearly as well). Into the mouth of spersed through this little work, this is fitted a tin vessel, which fits which the reader will be gratified and descends a little way down. It in consulting, and will probably be has a flat bottom perforated with induced to make others in his turn. many holes, and a good close cover ;

ON

ON THE PROCESSES EMPLOYED POR DEFACING WRITING ON PAPER, POR

DETECTING, AND REVIVING IT; AND A NOTICE OF AN INDELIBLE
INK.

(By B. H. Tarry, M.D. as abridged by M. M. Berthollet, Vauquelin,

and Deyeux.)

WV

RITING is removed either “ In some cases the gallic acid'is

by scraping with a knife, capable of recomposing the writing, or by means of acids. When writing that has beer made to disappear by has been scratched out, commonly chemical mcans ; but its attraction jounce or size is applied to the for the oxide of iron is not so strong paper, that the ink afterward used as is commonly supposed. The red may not run. If pounce bave been or brown oxide of iron, obtained employed, the strokes of the same from the sulphate or nitrate by pen will appear more slender, if means of alkaline carbonates, cada size, more full, than on other parts not combine with the gallic acid to of the paper. Immersion in warm form ink, unless the carbonic acid water for a few minutes will dis- have been expelled from the oxide solve and wash away size : alcohol of iron by some more potent acid. will have the same effect on pounce. It is the same with respect to the After the paper is taken out, it oxalic acid, and acidulous oxalate shuuld be dried slowly ; at first in of potash : when this acid or this the shade, till three parts dry, and acidulous salt has seized the oxide afterward between the leaves of a of iron, the gallic acid cannot debouk, or a quire of paper. While it stroy the combination, because it is drying the ink last used will has an inferior attraction for tho spread and sink into the paper oxide of iron. more or less. Generally indeed close “ If the writing have been deinspection with a good lens will stroyed by nitric or oximuriatic acid, show wbere any writing has been the gallic acid in tincture, infusion, scratched out, by the appearance of or decoction of galls will revive some loose or toro filaments.

it. “ If the means employed to obli- “Liquid prussiate of lime or pota terate writing have been such as to ash is a good re-agent, to detect the remove the whole of the iron from presence of iron. If the ink have the paper, every attempt to restore disappeared in consequence of the the writing must be vain. If some decomposition of gallic acid, as ferruginous compound remain, the when oximuriatic acid has been emcharacters may be re-produced in ployed, either of these will render their original form; though the co- it legible, causing it to appear of a Jour will vary, according to the na- light greenish blue while wet. If ture of the compound in which the oxalic acid have been employed to iron is concealed, and of thç rem obliterate the writing, the prussiates, agent employed.

will restore it of a reddish brown

colour, lage,

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colour. If nitric or sulphuric acid directions. They are owing to have been employed, the prussiate the sulpburetted bidrogen conibinof lime will show this by staining ing with the oxide of the ferrugithe paper Elue, but it cannot pro- nous nitrate. If the undulating duce the writing.

lines, or the letters that have been “Hidroguretted sulphurets of the restored, should disappear, they alkalis, or of the alkaline earths, may be reproduced by dipping the are very prompt and powerful tests paper into cold water. Beside the of ferruginous salts. The alkali, or traces of writing, and the undulatcarth, combines with the acid ; and ing lines just mentioned, the paper the sulphuretted hidrogen with the takes a yellow colour when it is oxide of iron, forming an bidro- not impregnated with an acid, and guretted sulphuret of iron. Iron in

a green more or less deep when it the state of red oxide is partly dis- is. The green colour will be deeper, oxidated by the hidrogen, water is in proportion as the acid was stronformed, and the iron passes to the ger, or in larger quantity. In all state of black oxide. This is the cases the paper retains the colour of case with writing turned rusty: these fresh butter after it is dry. The biI re-agents immediately change it droguretted sulphurets should be to a green black, much deeper than diluted with halt or two thirds their. gallic acid would give. A solution quantity of water before they are of sulphate of iron mixed with an used, as in their ordinary state they bidroguretted sulphuret produces a are too strong. very deep green black ink.

“ From what has been said, we « The same attractions are exert. may hope to restore writing, that ed when the hidroguretted tests are has been obliterated by any agent applied where writing has been ob- except the nitric acid : and if this literated by the oxalic acidule or the have been employed only in small oximuriatic or nitric acid. If the quantity, without the assistance of oxalic acidule were employed, the any other acid, and its action has characters will reappear of a green not been too long continued, on black or brown red. If the oximu- holding the paper to the fire the riatic acid, of a green black or pale writing will reappear of a rust corust colour. The less the revived lour. writing approaches a black, the “ With regard to the improvemore the iron was oxided in the ment of ink, little progress has been metallic salt decomposed, or the made since the time of Lewis. Toks less the iron was disoxided by hi- made by infusion, and with green drogen. The writing on which ni- sulpbate of iron, are of a Prussian tric acid has acted strongly cannot blue colour, light, pale when writo be reproduced: but on passing sulo ten with, but growing black as they phuretted bidrogen over the paper dry on the paper. Those made by where it was, waving lines of a decoction are blacker, thicker, and green black will be formed on form a more copious sediment, which the remotest parts to which the is of a dirty Prussian blue colour. sulphuretted hidrogen penetrates. Decoction extracts from galls all the These lines may be produced in soluble parts ; infusion takes up great number, and in different chiefly the gallic acid, and muci

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On the Process employed for defacing Writing on Paper, &c. lage, with a little extract and tan- forms with it a very black and nin. In the decoction the iron of purer ink; and the alkali in the the green sulphate beroines more solution facilitates the union of the oxided, and the extract and tannin oxide of iron with the gallic acid, acquire oxigen, by absorption from by combining with the sulphuric the atmosphere; and the iron in a acid of the sulphate. The oxigehigher state of oxidation, and the nized extract concurs in rendering oxigenized extract, produce a deeper the ink blacker, as does the oxide black with the gallic acid and tan- of iron more highly oxided. nin. The more abundant sediment “ Infusion of galls is preferable is owing to a larger quantity of ex- to the decoction, as it dissolves the tract and tannate of iron. In inks principle, that is essential to the made by infusion, the oxide of composition, and very little of those iron, extract, and tannin, increase that are foreign to it. Logwood their oxigenation very little, till they browns the ink, and loads it with come to dry on paper. Nitric acid its colour ; it is better therefore, to immediately obliterates writing with use in its sttad a small quantity of ink made by infusion, but that galls in addition to that directed by which has been made by decoction Lewis.' The following is the comresists its action much longer, on position of a good ink. account of the larger quantity of " Infuse in one litre (a wine extract in it.

quart] of rain or river water 125 “In proportion as the infusion or 'gran. [4 oz. troy) of bruised galls, decoction of galls grow's old, its letting them stand in the sun four surface is covered with mother, bours in summer, or six hours in which is the mucilaginous principle winter. This infusion may be used separated. This mother ceases to immediately after straining ; but it form in about a year, during which is better to let it stand four or six the pellicle produced on the surface months, removing the mother that should be removed three or four forms on the top now and then, times. The infusion or decoction and finally separating by filtration of galls grows brown as it becomes both this and the tannin that has oxigenized, takes an amber colour, fallen to the bottom. In this disand emits a pleasing smell; and, solvę 32 gr. [a troy ounce] of pow. when combined with green sulphate dered gum arabic; then add the of iron, no longer produces a Prus- same weight of finely powdered sian blue, but a green black. The sulphate of iron, superoxigenized amber colour of this infusion or de. by calcining it till it grows reddish; coction is owing to the oxigenized and continue shaking the mixture extract and taunin. The green co- till this is completely dissolved. The Jour of the ink arises from the mix- ink thus made is fine, light, and of fure of the black of the gallate of a purple ringe, but black when dried iron with the fawn colour of the on the paper. It is vearly, if not oxigenized tannin, which in this precisely, the composition of Guystate can no longer combine with ot's ink. the oxide of iron. If the tannin Dr. Tarry next proceeds to his be separated from the infusion or indelible ink, the composition of decoction by means of an alkali, which however he does not disclose. the green or red sulphate of iron He says only, that it contains neither

galls,

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