Czytaj książkę: «A History of Inventions, Discoveries, and Origins, Volume II (of 2)», strona 28
[Hops are extensively cultivated in Kent, Sussex, and Herefordshire; and to a less extent in Worcestershire, Wiltshire, Hampshire, Gloucestershire, Surrey, and several other counties.
From 50,000 to 60,000 acres of land are covered in England with hop-gardens, about one-half being in Kent; an excise duty of 18s. 8d. per cwt. is levied upon their produce. British hops are exported to Hamburg, Antwerp, St. Petersburg, New York, Australia, and other places. A trifling quantity is also imported, principally from Flanders. The duty on hops of the growth of Great Britain produced in 1842, £260,979.]
BLACK LEAD
To ascertain how old the use of black lead is for writing might be of some importance in diplomatics, as the antiquity of manuscripts ruled or written with this substance, or of drawings made with it, could then be determined.
I allude here to pencils formed of that mineral called, in common, plumbago and molybdæna, though a distinction is now made between these names by mineralogists. The mineral used for black-lead pencils they call reissbley, plumbago, or graphites; but under the term wasserbley and molybdæna they understand a mineral once considered to be the same as the former, but which, however like it may be in appearance, differs from it in being heavier, occurring much seldomer, and containing a new metal, almost of a steel-grey colour, exceedingly brittle, and named molybdænum. Plumbago, which is the substance here meant, when exposed to an open fire, is almost entirely consumed, leaving nothing but a little iron and siliceous earth. It contains no lead; and the names reissbley and bleystift have no other foundation than the lead-coloured traces which it leaves upon paper. The darker, finer, and cleaner the lines it makes are, the fitter it is for drawing and writing. These lines are durable, and do not readily fade; but when one chooses, they may be readily rubbed out. Black lead, therefore, can be used with more convenience and speed than any coloured earth, charcoal, or even ink.
It is well known that transcribers, more than a thousand years ago, when they wished their writing to be in a particular manner beautiful and regular, drew fine parallel lines, which they followed in writing. These lines may be still clearly distinguished in old manuscripts. In many instances, they have only been impressed on the parchment by some hard, sharp body; but they often exhibit a leaden colour; from which one might suppose that they had been drawn with our plumbago, and consequently believe that the use of this substance is as old as we must consider, from certain marks, the oldest ruled manuscripts. But, on a little reflection, one will be convinced that this would be a very fallacious conclusion. For lines so like those made with plumbago, that the eye can scarcely perceive the difference, may be made with lead958.
It can be proved that the ancients drew their lines with lead; and this could be done with more convenience, as this soft metal was easily rubbed off by the parchment, which, being harder and rougher than our paper, had therefore more body. It is well known that, formerly, when people wished to draw lines, a small round plate of lead, which could not so readily cut the parchment or become bent as a leaden style, was employed959.
Old manuscripts, ruled with lead-coloured lines, have been pointed out by modern diplomatists. Our learned Professor Schönemann, who was unfortunately hurried off by a premature death, has given a description of the Codex Berengaris Turonensis, of the eleventh or twelfth century, and the Codex Theophyli Presbyteri de Temperamento Colorum of the latter century, both preserved in the library of Wolfenbuttel; and remarks that lines are drawn on the first partly with a style and partly in a light manner with lead; but he says of the other, that it exhibits very fine lines drawn with a black-lead pencil960. Le Moine quotes a document of the year 1387, which is ruled with black lead, and at the same time says that the custom of ruling ceased about the year 1421 and 1424. The lines, therefore, after that period, became crooked and oblique961.
But the antiquity of black-lead pencils cannot be determined by the help of diplomatic documents. It might be traced out with more ease were it known by what mineralogical writer plumbago, and the uses of it, were first mentioned. The following is what I have remarked on this subject; but I suspect that there must be some older mention of it than any I have yet been able to find. I do not, however, believe that those who require more than bare conjecture will discover this mineral in the works of the Greeks and the Romans; for it cannot possibly be proved that it is to be understood under the terms plumbago, galena, molybdæna, and molybdoides, as has been confidently asserted by many, who, were it not superfluous, might easily be refuted. But in whatever obscurity these names may be involved, one can with certainty discover that they sometimes denote galena, or a real lead ore, or else some production of lead works.
The first author in whose writings I have as yet found certain mention of plumbago is Conrad Gesner, whose name I can never pronounce without respect. In his book on fossils, printed at Zurich in 1565, he says that people had pencils for writing which consisted of a wooden handle, with a piece of lead, or, as he believed, an artificial mixture, called by some stimmi Anglicanum. Such pencils must at that time have been scarce, because he has given a figure of them in a wood-cut. To judge by this, the pencil seems to have had a wooden sheath or covering.
Thirty years after, Cæsalpinus gave a more complete account of this mineral, which he calls molybdoides, because he thinks it was so named by Dioscorides. He says that it was a lead-coloured shining stone, as smooth as if rubbed over with oil; it gave to the fingers an ash-grey tint, with a plumbeous lustre, and pointed pencils were made of it for the use of painters and draftsmen. He adds, that it was called Flanders’ stone, because it was brought from the Netherlands to Italy962.
Three years after Cæsalpinus, a still better description was given by Imperato. The latter calls the black lead grafio piombino, and says that it is much more convenient for drawing than pen and ink, because the marks made with it appear not only on a white ground, but, in consequence of their brightness, show themselves also on black; because they can be preserved or rubbed out at pleasure; and because one can retrace them with a pen, which drawings made with lead or charcoal will not admit963. This mineral is smooth; appears greasy to the touch, and has a leaden colour, which it communicates with a sort of metallic lustre. It can resist for a long time the strongest fire; it even acquires in it more hardness, and therefore has been considered as a kind of talc. Sometimes it is foliaceous, and may be crumbled to pieces in scales; but it is frequently found denser and stronger, and in this case writing-pencils are made of it. The first kind was mixed with that clay called rubrica, and manufactured into crucibles, which were exceedingly durable in the fire. It is here seen that these Italians, at that time, were well acquainted with this mineral. It has been reckoned a species of talc by Justi, by Wallerius in the first edition of his mineralogy, and also by others. Its durability in resisting heat is certainly manifested, when it is kept in a close fire and between coals. But it is proved by the experiments of modern mineralogists, that in an open, strong, and long-continued fire, it becomes almost entirely consumed.
Bartholomew Ambrosinus, in the continuation of Aldrovandi’s Musæum Metallicum, printed at Bologna in 1648, uses the name lapis plumbarius. The short account which he gives of it has been borrowed from the two Italians last mentioned; but it deserves to be remarked, that even then he thought it worth his while to give Gesner’s figure enlarged.
In the works of Albertus Magnus, George Agricola, Encelius, Cæsius, Kircher, and many other old mineralogists, I have found no mention of black lead. But as the advantageous use of it for crucibles was known to Imperato, and as the crucibles made at Ips, which till very lately were employed by all the mints in Europe, and even in other parts, derived their superiority from plumbago being mixed with the blue clay, and as these crucibles are introduced more than once by Agricola without any mention of the addition, it must either at that time have not been usual, or it must have escaped the notice of this diligent man. How old then are the pits at Leizersdorf, which furnish plumbago for the crucibles of Ips or Passau? I know of one mineralogist only who has described that district, but on this subject he has given us no information.
I am equally unacquainted with the time when the pits in Cumberland, which, as is well known, produce the best plumbago, were discovered. They are situated on the Borrowdale mountains, about ten miles from the town of Keswick. The families to whom these pits belong, according to an established regulation, can open them only once every seven years, and take out but a certain quantity of the mineral, in order to keep up the price, and prevent the pits from being exhausted964. This production is called there black lead, kellow or killow, wad or wadt, which words properly mean black965. I have found no older information in regard to these pits than that of Merret, who wrote in the year 1667, and who calls this mineral nigrica fabrilis, because it had then no Latin name966. Pettus remarked, in his Fleta Minor, published 1683, that the pencils made from it were inclosed in fir or cedar. It is related by Robinson967 and others, that at first the country-people around Keswick marked their sheep with it. Afterwards the art was discovered of employing it for earthenware, and for preserving iron from rust. The last-mentioned author says also, that it is used by the Dutch in dyeing, in order to render black more durable, and that it is bought up by them in large quantities for that purpose. But this is only a pretence. I am inclined to think that they prepare from it black-lead pencils.
The greater part of the plumbago at present used in commerce, but which, as far as I know, is fit only for iron-black, comes from Spain, where it is dug up in the neighbourhood of Ronda, a town in Grenada, a few miles distant from the sea; but, in regard to the antiquity of these pits, I have found no information. In commerce, it is called potloth; and the mills, such as those at Bremen, where it is ground fine, are named potloth mills, an appellation which in all probability has been borrowed from the Dutch, among whom potloot signifies as much as potters’ lead. From this word the French have made potelot, which however in many dictionaries is omitted. If I am not mistaken, this mineral was first found in France at a very late period in Upper Provence, near Curban, and not far from the river Durance, between Sisteron and Gap, from which it is sent to Marseilles.
It appears to me probable, that in the sixteenth century the use of plumbago was first introduced into Italy, a country which abounds with draftsmen and drawing-schools; where other minerals had been long used for drawing, and where the best kinds had been carefully sought out. It is likely, therefore, that some one may have made a trial with plumbago, induced by its appearance; and indeed nothing but a trial was necessary to show its superiority to charcoal, and to black and red chalk. I am inclined to think also, that the earliest mention of it will be found in the oldest Italian works on drawing, rather than in those on mineralogy, to the authors of which this substance first became known by its use. For a long time, all the black-lead pencils employed in Germany and in the neighbouring countries were made at Nuremberg. I shall here observe, that the very convenient method of wiping out writing made with a black-lead pencil, by means of Indian rubber, was discovered about twenty or thirty years ago, and, as I believe, first in England.
After I had completed this article, Professor Fiorillo, who as an artist has studied the master-pieces, and as a man of letters the writings of the Italians, communicated to me, at my request, the following information, which at any rate will form an additional fragment towards the history of drawing. The pencils first used in Italy for drawing were composed of a mixture of lead and tin fused together, and the proportion was two parts of the former and one of the latter968. To obliterate a drawing or piece of writing, it was rubbed over with crumbs of bread. A pencil of this kind was called stile. Petrarch has immortalized a painter named Simone Memmi by a couple of sonnets, out of gratitude for a picture of his beloved Laura969. In these he says that the artist made the drawing with a stile in carte. The author here evidently alludes to a drawing-pencil, and not to a graver, as some have supposed. Boccacio, a scholar of Petrarch, celebrates an artist who was equally expert at drawing with the stile, the pen, and the pencil. Michael Angelo also, who died in 1564, says, in a sonnet on Vasari, quoted by Fiorillo, “Se con lo stile e co’ colori avete.” Such pencils were long used also in Germany; and formerly they were found at the most common writing-desks.
The use of red and black chalk seems to be more modern. The former is called by the Italians matita rossa, and the latter matita nera. This name is derived from hæmatites. Vasari celebrates Baccio Bondinelli, who died in the middle of the sixteenth century, because he could handle equally well lo stile, e la penna, e la matita rossa e nera. Baldinucci says, that the best red chalk comes from Germany; good black chalk from France; but the very best from Spain, whence that of the first quality is obtained at present.
I can, however, point out no mention of our plumbago in the works of the old Italian artists. Armenini, who wrote at the end of the sixteenth century, relates how pupils were taught to draw a hundred years before his time970. He says that they made the first sketches with piombo over cannella col lapis nero, and afterwards filled them up with a pen. But when his whole description is read, there can remain no doubt that the substance here meant is black chalk. Baldinucci, who did not write till 1681, has introduced particularly into his dictionary matita rossa, nera, and also lapis piombino; and says that the last-mentioned is an artificial production, which gives a leaden colour, and is employed for drawing. It is evident therefore that the author here alludes to plumbago, which was then very common. But when Bottari says971 that artists first began to use red and black chalk in the time of Vasari, whereas lapis piombino only was employed before that period, he has named plumbago, commonly used in his time, instead of the metallic pencil which was called stile. If I am not mistaken, the Italians have no proper appellation for black lead, but call it sometimes matita and sometimes piombino.
[Great difficulty was formerly experienced in protecting the Borrowdale black-lead mine from robbery. At present, the treasure is protected by a strong building, consisting of four rooms upon the ground floor; and immediately under one of them is the opening, secured by a trap-door, through which workmen alone can enter the interior of the mountain. In this apartment, called the dressing-room, the miners change their ordinary clothes for their working-dress as they come in; and after their six hours, post or journey, they again change their dress, under the superintendence of the steward, before they are allowed to go out. In the innermost of the four rooms two men are seated at a large table, sorting and dressing the plumbago, who are locked in while at work, and watched by the steward from an adjoining room, who is armed with two loaded blunderbusses. In some years the net produce of the six weeks’ annual working of the mine has, it is said, amounted to from 30,000l. to 40,000l.
An inferior kind of plumbago is imported from Mexico and Ceylon; and a composition with which more common pencils are manufactured is made of a mixture of plumbago-powder, lamp black and clay.
A useful and convenient application of the black lead in the form of minute cylinders which slightly projected from a cylindrical cone, and which was fitted to a pencil-case, was patented in 1822 by Mr. Mordan, and has come into general use: the cylindrical form of the plumbago is produced by passing square strips of it through holes in a ruby, somewhat in the manner of wire-drawing. It is stated that the supply of plumbago from the Cumberland mine is almost exhausted; fortunately, a process has been devised by which the same firmness and equality may be communicated to the powder by compression. This is effected by carefully washing and grinding the dust obtained in sawing plumbago into thin plates, sifting it through spaces less than the 1/50000th part of an inch, and placing it under a powerful press, on a strong die or bed of steel, with air-tight fittings. The air is then pumped from the dust, and while thus freed from air, a plunger descends upon it and it becomes solidified. The power employed to perform this operation is estimated at 1000 tons, several blows having been given, each of this power. This process was invented by Mr. W. Brockedon, the talented draftsman of Alpine and Italian scenery.]
SAL-AMMONIAC
It is not very probable that Dioscorides, Pliny, and others who lived nearly about the same time, were acquainted with sal-ammoniac, or mentioned it in their works; for no part of mineralogy was then so defective as that which is the most important, and which treats of salts. The art of lixiviating earths and causing saline solutions to crystallize was then so little known, that, instead of green vitriol, vitriolic minerals, however impure, were employed in making ink, dye-liquors, and other things. Places for boiling vitriol were not then established, and therefore Pliny beheld with wonder blue vitriol, which in his time was made only in Spain, as a thing singular in its kind, or which had not its like. On this account those salts only were known which occur in a native state, or which crystallize as it were of themselves, without any artificial preparation, as is the case with bay salt. But that neutral salt, formed of muriatic acid and ammonia, occurs very seldom in a native state, and almost exclusively among the productions of volcanoes. I do not, however, suppose that this volcanic sal-ammoniac was the first known, but that it was first considered to be sal-ammoniac after that salt had been long obtained by another method, and long used.
But even if it should be believed that our sal-ammoniac was known to the ancients, how are we to discover it with certainty in their writings? This salt has little or nothing by which these writers could characterize it. Neither its external form nor taste is so striking that it could be described by them with sufficient precision. The use of it also could not at that time be so important and necessary, as to enable us to determine whether they were acquainted with it; whereas, on the other hand, green vitriol and alum can easily be distinguished among the materials for dyeing.
Nay, if this salt had been then made, as it is made at present in Egypt, and if any allusion to it were found, one might readily conjecture that sal-ammoniac were really meant. But even though it must be admitted that traces of sublimation being employed occur in the writings of Dioscorides and others, who lived nearly at the same period, we are not authorized to suppose that the knowledge of it was sufficient for the preparation of this salt.
Besides, there are two properties with which the ancients might have accidentally become acquainted, and which in that case would have been sufficient to make known or define to us this salt. In the first place, by an accidental mixture of quicklime, the strong smell or unsupportable vapour diffused by the volatile alkali separated from the acid might have been observed. In the second place, it is very possible that the complete volatilization of this salt on burning coals may have been remarked; for it had been long known that common salt decrepitates in the fire. This excited wonder, and in examining other salts people were accustomed to observe whether they possessed that property also. Had any one, with this view, thrown a bit of sal-ammoniac on a burning coal, he must have seen with astonishment that instead of decrepitating it became entirely volatilized. For this experiment, however, very pure sal-ammoniac would have been necessary. Had a little common salt been mixed with it, decrepitation would not have been altogether prevented; and if the sal-ammoniac had been rendered impure by earthy particles, as is almost always the case with the volcanic, some earth at least would have remained behind on the coals.
The name sal-ammoniacus is indeed old; but as those who, in consequence of the name, considered the alumen of the ancients to be our alum, and their nitrum to be our saltpetre, were in an error, we should be equally so were we to consider their sal-ammoniac to be the same as ours. Our forefathers believed that the ancient writers were acquainted with all minerals, as well as with all plants; and when they discovered a new one, they searched in old books till they found a name which would suit it, or which at any rate had not been given to another. Our sal-ammoniac, in all probability, acquired in the same manner its name, which is not often to be found in the writings of the ancients972.
When everything they have said of it is collected and impartially examined, no proofs will be found that under that name they understood our sal-ammoniac. On the contrary, one will soon be convinced that sal-ammoniacus was nothing else than impure marine salt. As the ancients were not acquainted with the art of separating salts, of refining and crystallising them, they gave to each variety or kind in the least different, which was distinguished either by the intermixture of some foreign substance or by an accidental formation, a particular name; and, considering the wants of that period, this method was not so bad. For among the impure saline substances, there were always some which were found to be fitter than others for certain purposes. On this account they distinguished with so much care misy, sory, chalcitis and melanteria, instead of which we use a substance contained in all these minerals, that is to say, green vitriol. Our apothecary shops however have at present the lixivious salt under the name of various plants, from which it is extracted, with different degrees of purity.
When this is known, it will excite no wonder that the sal-ammoniacus of the ancients was nothing else than our common salt. Dioscorides and Pliny speak of it expressly as a kind of this salt; and Columella973, in a prescription for an eye-salve, recommends rock-salt, either Spanish, Ammoniacal, or Cappadocian. Pliny says974 that sal-ammoniacus was found in the dry sandy deserts of Africa, as far as the oracle of Ammon. It is stated, both by him and Dioscorides975, that this salt can be split or broken into smooth pieces; and the former adds, that the best are white and transparent; that it however has an unpleasant taste, but can be used in medicine. In like manner later physicians, when they wish to prescribe common salt, recommend in particular the ammoniac. Thus Aetius, who lived in the fifth century, remarks, that when fossil, or as we say at present native salt, is employed, ammoniac or Cappadocian ought to be chosen.
From what is said by Pliny, it may with certainty be concluded that this salt was dug up from pits or mines in Africa; for he relates, that it appeared wonderful that a piece of it, which in the pit was very light, became, on exposure to the open air, much heavier. Without repeating the explanation which he gives of this phænomenon, I shall only remark, that many kinds of rock-salt, taken from the mines of Wieliczka, experience the same change in the air; so that blocks which a labourer can easily carry in the mine, can scarcely be lifted by him after they have been some time exposed to the air. The cause here is undoubtedly the same as that which makes many kinds of artificial salt to become moist and to acquire more weight. In this case it is owing to some impurity, such as muriate of lime, which is called sal-ammoniacus fixus976, and which attracts from the atmosphere so much moisture, that it deliquesces in it to the so-called oil of lime.
Synesius, who was born in Egypt in the fifth century, in the Pentapolitan town Cyrene, and who resided as bishop in Ptolemais, the capital of the district, says, in a letter wherein he describes many rarities of his native country, that what was called sal-ammoniacus977, both according to its appearance and taste, was a salt of a good quality, fit for use; that it lay under a soft kind of stone which covered it like a crust, and that it could be easily dug up when this stone was removed.
Herodotus, Strabo, Arrian, and others, speak of rock-salt which was dug up in Ammonia, and carried thence as an article of merchandise. The first mentions a hill of salt; and we are told by the last, that native salt was brought to Egypt as a present to the king and others, from the neighbourhood of the oracle of Ammon, by the priests of that place, in boxes made of palms worked together. Many pieces were three inches in length; and because this substance was purer than bay salt, and as clear as crystal, it was particularly employed in sacrifices. This salt is certainly that which, under the name of sal-ammoniacus, was sent from Egypt to the king of Persia, like the water of the Nile, as is related by Athenæus from an historian long since lost978.
It is also certain that the old Arabian physicians, Avicenna and Serapion, who both lived in the eleventh century, under the name sal-ammoniacus understood nothing else than rock-salt. The former says that it ought to split easily, and to be clear and transparent like crystal; and the latter states that this salt is cut from the solid rock, and that it is sometimes clear as crystal, sometimes reddish, sometimes blackish, sometimes of another colour, sometimes hard, and sometimes friable, or, as the translator expresses it, pulverulent. All these colours and properties are not uncommon in rock-salt, and always proceed, no doubt, from an admixture of ferruginous earth. Serapion says that this salt was obtained from Corasini. I shall leave it to others to determine where this country was situated. He often names it, and says that mala granata and bezaar were obtained from it. But who knows how the name was written in the original? And the Arabian author perhaps did not mention the place where the salt was dug up, but that from which, in his time, it was procured979.
In regard to the purpose to which the ancients applied their sal-ammoniacus, it appears that it required only common salt and not sal-ammoniac. It is oftenest mentioned by the physicians, because it was the purest table salt that could then be procured. On that account it has been praised by Scribonius Largus, who lived in the first century, and by Aetius who lived in the fifth, as well as by Avicenna, Serapion, and others. I have however not yet met with it in the writings of Hippocrates or Galen. In the works of the Greek agriculturists it occurs in a recipe for the preparation of a cement employed to close up wine vessels980. According to a recipe of Apicius, in his book on cookery, sal-ammoniacus was to be roasted. By these means this rock-salt lost its water of crystallization and became stronger. On this account, in Transylvania, Siberia, and other countries, before it is brought to the table it is pounded and roasted. Of our sal-ammoniac, however, were it roasted, very little would remain. But whether the ammonium which Palladius recommends for a cement981 be that salt, I will not pretend to determine. On the other hand, I have no hesitation to contradict the old commentator on Ovid, who, in a passage where the poet recommends sal-ammoniacus in making a cosmetic water, understands the resin or gum of that name. Ovid however had no intention that young women should lacker themselves.
For the reasons therefore already mentioned, I am convinced that the sal-ammoniacus of the ancients was rock-salt, and not our sal-ammoniac. The oldest commentators also on these writers had no idea of any other than rock-salt; and it was not till a later period, when our sal-ammoniac was introduced into commerce, and acquired that name, that the most learned commentators began expressly to remark, that the new sal-ammoniac, notwithstanding its appellation, was different from the sal-ammoniacus of the ancients. As this could not then be obtained, people used the former, which they considered only as an artificial substitute for the latter, though it was incapable of supplying its place. But in more modern times, when our sal-ammoniac became common, and physicians and mineralogists no longer took the trouble to read the works of the ancients, some of them, if not the greater part, spoke in such a manner as if our sal-ammoniac had been the sal-ammoniacus of the ancients; and it was then generally believed that it had been, at any rate, known and used since the time of Dioscorides and Pliny.
No one has maintained this with greater confidence and zeal than F. I. W. Schröder982, whose judgement however was perverted by alchemistic conceits. According to his assertion, the Egyptians practised from the earliest periods the art of making sal-ammoniac, but they kept it a secret; and he obscurely hints at the purpose for which these great chemists used so much salt. He refers, on this occasion, to what Pliny says of flos salis983, in which he thinks he can find the martial sal-ammoniac984 flowers of our chemists, or the so-called flores salis ammoniaci martiales. Those who cannot make this discovery he declares to be ignorant and blind. This decision, however, when the character of the person who gives it is considered, cannot dissipate a single doubt. It is certain that what Dioscorides and Pliny call flos salis has never yet been defined. It was moist, oily, and saline; and in the vessels, in which it was sent from Egypt, was grey at the top, saffron-coloured at the bottom, and emitted a bad smell. The most ingenious conjecture was that of Cordus985, who thought that it might be sperma ceti; but though I should prefer this opinion to that of Schröder, I must confess that, on the grounds adduced by Matthioli and Conrad Gesner, it has too much against it to be admitted as truth.
