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these appear to have been in some measure superseded by Dr. Bancroft's discovery of the utility of the quercitron bark : a discovery of which the advantages were secured to him by act of parliament for a term of years, although he failed in his application for an extension of that term in 1798, potwithstanding the advantage which the public had derived from the singularly liberal manner in which he had conducted the monopoly. In less than twelve months after that time, the bark rose to three times the price at which he had constantly supplied it, and at which he would have been bound to supply it for another term of seven years, if the bill had been passed. He has presented us with an immense variety of experiments and of practical directions relating to the use of this substance, and his communications must be of great value to the intelligent manufacturer.
We cannot altogether agree with the author in the decided preference which he appears to entertain for the process of bleaching by the oxymuriatic acid, (II. 176.) which seems at present to have become almost universal, not a little to the advantage of manufacturers and tailors, and to the prejudice of the public in general. Sir Humphry Davy has found that, even when neutralized by an excess of lime, the muriatic acid, formed during the process of bleaching, is injurious to the fibres of the cloth; (Elem. p. 242.) and whatever precautions it may be possible to employ for avoiding this evil, we are persuaded, from continued experience, that they are not commonly adopted by manufacturers, either in bleaching cotton or paper. • the rubia tinctorum, is a very well known and impor
Madder tant vegetable, much employed for dyeing red with an aluminous basis, on common woollen cloths. Its effect, in giving a red colour to the bones of animals that feed on it, was first observed by Lemnius in the 16th century, and is now well known to physiologists. Madder does not appear to be capable of affording a prosubstantive colour; and it is absolutely necessary that the basis should be separately applied to the linen or cotton which is to be dyed with it. Galls are commonly employed by practical dyers as a preparation for the aluminous impregnation, in order to promote the attachment of the alum to the cloth ; but they add nothing to the durability of the colour.
The rubia peregrina, or Smyrna madder, is principally used in the complicated process for dyeing the Turkey red on cotton, with the assistance of oil, alum, galls, and some blood, which seems to brighten the colour, besides that of the substances which have passed through the alimentary canal of the sheep, carrying with them some of the gastric fluids, and which, in Dr. Bancroft's opi
nion, are highly conducive to the stability of the colour, although some former chemists have much ynderrated their efficacy.
Brasil wood is the heart of the caesalpinia echinata; its name is not derived from the country which affords it; the old name of kermes having been grana di brasile, implying the colour of fire or live coals; and the country of Brasil was afterwards so denominated from its producing this substance, which affords a dye of the same hue. The rose colour, which it communicates to water, is destroyed by confinement for a few days with sulfurated hydrogen: but the same effect was not produced by a protoxyd of tin, which would have destroyed the colour of indigo. Acids make the infusion yellow, but alum reconverts it to red, and affords a precipitate, which is employed as an inferior sort of carmine; and the addition of an alkali throws it down in greater abundance.
Logwood, the haematoxyton campechianum, is sometimes used for dyeing purple, with a mordant of muriosulfate of tin, tartar, and sulfate
of copper; the latter Dr. Bancroft thinks superfluous, since it affords only a fugitive colour: but the most extensive employment of logwood is for dyeing black.
For browns, the mangrove bark, rhizophora mangle, the mahogany, and several species of walnuts are recommended, principally with bases of iron. Galls give, with an aluninous basis, a fawn, or light cinnamon colour.
In the fourth part of the work, the author gives a few practical directions only respecting the mixtures of colours, and proceeds to the subject of black dyes and writing ink. He objects altogether to the chemical distinctions and definitions of the gallic and tannic principles, as contained in astringent vegetables, and is rather disposed to consider the colouring matter as distinct, and as not agreeing in general with the characteristic marks of any particular chemical combination. Thus, the quercitron, mangrove and mahogany bark are astringent to the taste, precipitate glue, and tan leather, but produce no darker tint than an olive. Catechu tans admirably well, but affords only a snuff colour with iron: on the other hand, the walnut bark and logwood afford a black ink, but are not astringent to the taste, and do not precipitate glue. Dr. Bancroft imagines that logwood bas no claim to the title of an astringent in a medical sense ; but we have reason to think that in this respect he is greatly mistaken. We may add the artichoke to the number of vegetables which have no astringent taste, and yet blacken iron: the Jerusalem artichoke, which has a taste nearly similar to that of the common artichoke, does not possess the same property. The gallic acid, so called, blackens the peroxyds of iron, but Dr. Bancroft is rather disposed to attribute this effect
to some accidental mixture of the colouring matter, than to the essential constitution of the substance itself.
Ink may be deprived of its blackness by a stream of sulfureted hydrogen, which can only act by combining with the oxygen: by exposure to the air it recovers its colour, with a fresh supply of oxygen. It is well known that the ink of the ancients was carbonaceous: Indian ink, according to Cuvier, is obtained from some species of sepia. Dr. Bancroft finds the best proportion of galls three times the weight of the sulfate of iron; and if a portion of logwood be employed, half as much of the galls may be omitted: the sulfate of copper, recommended by Chaptal, he thinks useless: it is true that it tends to prevent mouldiness; but we have found inconvenience from its corroding and blunting the penknife, when it happens to touch it. Dr. Bancroft directs twelve ounces of galls to be boiled with six of logwood in five quarts of soft water for two hours, the decoction to be strained, and made up one gallon, to which five ounces of sulfate of iron, five of gum arabie, and two of muscovado sugar are to be added. A simpler mode, lately recommended by a celebrated chemist, is to infuse three ounces of galls, one of logwood, one of sulfate of iron, and one of gum arabic in a quart of cold water for a week, and to add four grains of corrosive sublimate, in order to prevent mouldiness. We may add, that when economy is an object, the soluble parts of the galls may be much more effectually extracted by the repeated affusion of fresh portions of the water, than by steeping them in the whole at once.
The best black woollen cloths are first dyed red with madder, and blue with indigo or woad, since without this preparation it would be necessary to use so much of the common black dye as would materially injure the texture of their fibres. Sometimes, in coarser cloths, logwood only is employed for the first dye, with a salt of copper: in this mamer a black is produced, wbich inevitably turns in a short time to a brown.
In dyeing silk black, the galls are applied first, being more strongly attracted by the silk than the icon, and they may therefore be considered as the true mordant; after this, alternate immersions in a solution of sulfate of iron, and in a decoction of logwood are frequently repeated, in order to obtain a deep black; but to cotton; the iron is usually applied first. Some of the black vats, with iron and various vegetable substances, are suffered to remain unemptied for centuries, being supposed to have their qualities improved by age. For a probsubstantive topical black, the addition of vinegar and nitric acid to galls and sulfate of iron is found to increase the durability of the dye, without any corrosion of the substance of the calico.
Dr. Bancroft has investigated the whole subject of black dyes and inks with great attention, and has made many elaborate experiments respecting them. Some of these experiments have indeed been productive of no immediate practical improvement; but in these, and in other similar instances, he describes his fail. ures with a degree of candour which does him no less honour than his success on more fortunate occasions. We sincerely wish that he may be enabled long to continue his favourite pursuits, and that the public may hereafter profit by the additions' con tingent on the prolongation of a life, of which the sixty-ninth year is now passing away.'
In vol. ij, p. 325, 1. 16, by the oxide,' we suppose is meant the oxide of tin ; and p. 361, 1. 10, by a little,' probably a little lime.
Art. XV. 1. Remarks on the Calumnies published in the Quarter
ly Review, on the English Ship-builders. 1814. 2. Substance of the Speech of William Harrison, Esq. before the
Select Committee of the House of Commons, on East India
built Shipping. 1814. 3. Minutes of the Evidence taken before the Select Committee, to whom the several Petitions of the Ship-builders and others interested in the Building and Equipment of Ships, built in the
East Indies, were referred, &c. Ordered, by the House of Com
mons, to be printed. 1914. 4. The Substance of the Speech of John Adolphus, Esq. on sum
ming up the Case of the English Ship-builders, ge. 1814.
T was not to be expected that words, which are but the imper
fect representatives of things, should be exempt from that universallaw of change which operates on the things themselves. Among others, the word. calumny,' which, if Dr. Johnson's authority be worth any thing, was once used to signify 'false charge-groundless accusation'-is now very frequently employed to express an Sunpleasant truth,' and sometimes the opposite of its original meaning. In the instance before us, we shall have no difficulty in shewing that for the calumnies of the Quarterly Review,' we might, without the least violation of truth, substitute 'true charges, or * well-founded accusations. We did not, however, prefer charges or accusations, either true or false, against the English ship-builders; though in the course of our examination of certain important papers on the state of oak timber, of the navy, and of recent improvements in naval architecture, we had occasion to animadvert on some part of the conduct of the Thames ship-builders; and this is a distinction which we beg may be kept in view. Our
remarks indeed were equally applicable to modern built ships of war in the King's yards; nay, the very first ship that caught our attention was the new first-rate, the Royal Charlotte, and we blended in the same censure the Ocean and Foudroyant with the Albion and the Ajax. But these gentlemen, or their indiscreet advocates, were so very tender of their own handicraft, that they instantly levelled their whole artillery against us through the medium of the daily prints. They, therefore, and not we, were the aggressors. We have little disposition for controversy, and still less desire to speak of our own labours : and however unpleasant so serious a charge as that of calumny may be to those who wish to stand well with the public, we should probably have submitted in silence to be pestered with a popinjay; and this the more readily, when we found that the champion of the Thames builders had brought to the task of writing Remarks' on our 'calumnies' no one qualification beyond that of dauntless assurance, and a fearless contempt of truth.
We now find ourselves, however, literally put upon our trial ; we are attacked unmercifully by a host of lawyers and attorneys, purveyors, ship-builders, timber-merchants, underwriters, ropemakers, twine-spinners, and the whole click connected with the shipping interest of the Thames; some of whom are our accusers, and others are brought forward to give evidence against us before a Select Committee of the House of Commons; the object of all is that of refuting our original opinions and falsifying our facts. Nothing therefore remains for us but 'to play the part of advocates' in our own cause, which, according to the writer of the Remarks,' is one of our grievous offences. Before we proceed to justify, it may not be out of place to say a few words on the general character of the articles we propose to examine.
The author of the 'Remarks on the Calumnies of the Quarterly Review' has indulged in all the latitude which this sweeping title may be supposed to give him-some of his remarks having nothing to do with the question, others being very remotely connected with it: he does not attempt to argue; but he declaims and asserts, and moralises and whimpers; he is sometimes scur rilous, and sometimes ventures to impute motives to us which could exist only in his own mind. The blunders and misrepresentations that occur in every page afford the best evidence of the utter incapacity of the writer for subjects of this kind; and if we should venture to designate him, from his works, we should say
he is one of those inferior instruments of the law, who, in our times, have succeeded in persuading mankind, that the most ordinary concerns of life require their helping hand, and who thus contrive to put their paw into every man's mess.'
The opening speech of the learned counsel, William Harrison,