Volume 4, Slice 1 Part 17 (1/2)
Worsted yarn spun on the English system, as well as woollen yarn and fabrics made from them, contain oil which has been incorporated with the wool to facilitate the spinning. This oil must be got rid of previous to bleaching, and this is effected by scouring in warm soap with or without the a.s.sistance of alkalis.
The actual bleaching of wool may be effected in two ways, viz. by treating the material either with sulphurous acid or with hydrogen peroxide. Sulphurous acid may either be applied in the gaseous form or in solution as bisulphite of soda. In working by the first method, which is technically known as ”stoving,” the scoured yarn is wetted in very weak soap containing a small amount of blue colouring matter, wrung or hydro-extracted and then suspended in a chamber or stove.
Sulphur contained in a vessel on the floor of the chamber is now lighted, and the door having been closed, is allowed to burn itself out. The goods are left thus exposed to the sulphur dioxide overnight, when they are taken out and washed in water. For piece goods a somewhat different arrangement is employed, the pieces pa.s.sing through a slit into a chamber supplied with sulphur dioxide, then slowly up and down over a large number of rollers and ultimately emerging again at the same slit. Wool may also be bleached by steeping in a fairly strong solution of bisulphite of soda and then was.h.i.+ng well in water.
Wool bleached with sulphurous acid or bisulphite is readily affected by alkalis, the natural yellow colour returning on was.h.i.+ng with soap or soda. A more permanent bleach is obtained by steeping the wool in hydrogen peroxide (of 12 volumes strength), let down with about three times its bulk of water and rendered slightly alkaline with ammonia or silicate of soda. Black or brown wools cannot be bleached white, but when treated with peroxide they a.s.sume a golden colour, a change which is frequently desired in human hair.
_Bleaching of Silk._
In raw silk, the fibre proper is uniformly coated with a proteid substance known as _silk-gum, silk-glue_ or _sericine_ which amounts to 19-25% of the weight of the material, and it is only after the removal of this coating that the characteristic properties of the fibre become apparent. This is effected by the process of ”discharging” or ”boiling-off,” which consists in suspending the hanks of raw silk over poles or sticks in a vat containing a strong hot soap solution (30% of soap on the weight of the silk). The liquor is kept just below boiling point for two or three hours, the hanks being turned from time to time.
During the process, the sericine at first swells up considerably, the fibres becoming slippery, but as the operation proceeds it pa.s.ses into solution. It is important that only soft water should be used for boiling-off since calcareous impurities are liable to mar the l.u.s.tre of the silk.
The silk is now rinsed in weak soda solution and wrung. In this condition it is suitable for being dyed, but if it is to be bleached, the hanks are tied up loosely with smooth tape, put into coa.r.s.e linen bags to prevent the silk becoming entangled, and boiled again in soap solution which is half as strong as that used in the first operation.
The hanks are now taken out, rinsed in a weak soda solution, washed in water and wrung.
The actual bleaching of silk is usually effected by stoving as in the case of wool, with this difference, that the operation is repeated several times and blueing or tinting with other colours is effected after bleaching. Silk may also be bleached with peroxide of hydrogen, but this method is only used for certain qualities of spun silk and for tussore.
_Ornamental feathers_ are best bleached by steeping in peroxide of hydrogen, rendered slightly alkaline by the addition of ammonia. The same treatment is applied to the bleaching of _ivory_. If peroxide of hydrogen could be prepared at a moderate cost, it would doubtless find a much more extensive application in bleaching, since it combines efficiency with safety, and gives good results with both vegetable and animal substances. (E. K.)
FOOTNOTES:
[1] Besides being used for cotton goods, plate singeing is also employed for certain cla.s.ses of worsted goods (alpacas, bunting, &c.), and for most union goods (cotton warp and worsted weft).
[2] A machine working on this principle has been constructed by F.
Binder, and the makers of the machine (Messrs Mather & Platt, Ltd.) claim that it does better service than the machines constructed on the older principle.
BLEAK, or BLICK (_Alburnus lucidus_), a small fish of the Cyprinid family, allied to the bream and the minnow, but with a more elongate body, resembling a sardine. It is found in European streams, and is caught by anglers, being also a favourite in aquariums. The well-known and important industry of ”Essence Orientale” and artificial pearls, carried on in France and Germany with the crystalline silvery colouring matter of the bleak, was introduced from China about the middle of the 17th century.
BLEEK, FRIEDRICH (1793-1859), German Biblical scholar, was born on the 4th of July 1793, at Ahrensbok, in Holstein, a village near Lubeck. His father sent him in his sixteenth year to the gymnasium at Lubeck, where he became so much interested in ancient languages that he abandoned his idea of a legal career and resolved to devote himself to the study of theology. After spending some time at the university of Kiel, he went to Berlin, where, from 1814 to 1817, he studied under De Wette, Neander and Schleiermacher. So highly were his merits appreciated by his professors--Schleiermacher was accustomed to say that he possessed a special _charisma_ for the science of ”Introduction”--that in 1818 after he had pa.s.sed the examinations for entering the ministry he was recalled to Berlin as _Repetent_ or tutorial fellow in theology, a temporary post which the theological faculty had obtained for him. Besides discharging his duties in the theological seminary, he published two dissertations in Schleiermacher's and G.C.F. Lucke's _Journal_(1819-1820,1822), one on the origin and composition of the Sibylline Oracles ”uber die Entstehung und Zusammensetzung der Sibyllinischen Orakel,” and another on the authors.h.i.+p and design of the Book of Daniel, ”uber Verfa.s.ser und Zweck des Buches Daniel.” These articles attracted much attention, and were distinguished by those qualities of solid learning, thorough investigation and candour of judgment which characterized all his writings. Bleek's merits as a rising scholar were recognized by the minister of public instruction, who continued his stipend as _Repetent_ for a third year, and promised further advancement in due time. But the att.i.tude of the political authority underwent a change. De Wette was dismissed from his professors.h.i.+p in 1819, and Bleek, a favourite pupil, incurred the suspicion of the government as an extreme democrat. Not only was his stipend as _Repetent_ discontinued, but his nomination to the office of professor extraordinarius, which had already been signed by the minister Karl Altenstein, was withheld. At length it was found that Bleek had been confounded with a certain Baueleven Blech, and in 1823 he received the appointment.
During the six years that Bleek remained at Berlin, he twice declined a call to the office of professor ordinarius of theology, once to Greifswald and once to Konigsberg. In 1829, however, he was induced to accept Lucke's chair in the recently-founded university of Bonn, and entered upon his duties there in the summer of the same year. For thirty years he laboured with ever-increasing success, due not to any attractions of manner or to the enunciation of novel or bizarre opinions, but to the soundness of his investigations, the impartiality of his judgments, and the clearness of his method. In 1843 he was raised to the office of consistorial councillor, and was selected by the university to hold the office of rector, a distinction which has not since been conferred upon any theologian of the Reformed Church. He died suddenly of apoplexy on the 27th of February 1859.
Bleek's works belong entirely to the departments of Biblical criticism and exegesis. His views on questions of Old Testament criticism were ”advanced” in his own day; for on all the disputed points concerning the unity and authors.h.i.+p of the books of the Old Covenant he was opposed to received opinion. But with respect to the New Testament his position was conservative. An opponent of the Tubingen school, his defence of the genuineness and authenticity of the gospel of St. John is among the ablest that have been written; and although on some minor points his views did not altogether coincide with those of the traditional school, his critical labours on the New Testament must nevertheless be regarded as among the most important contributions to the maintenance of orthodox opinions. His greatest work, his commentary on the epistle to the Hebrews (_Brief an die Hebraer erlautert durch Einleitung, ubersetzung, und fortlaufenden Commentar_, in three parts, 1828, 1836 and 1840) won the highest praise from men like De Wette and Fr. Delitzsch. This work was abridged by Bleek for his college lectures, and was published in that condensed form in 1868. In 1846 he published his contributions to the criticism of the gospels (_Beitrage zur Evangelien Kritik_, pt. i.), which contained his defence of St John's gospel, and arose out of a review of J.H.A. Ebrard's _Wissenschaftliche Kritik der Evangelischen Geschichte_ (1842).
After his death were published:--(1) His _Introduction to the Old Testament_ (_Einleitung in das Alte Testament_), (3rd ed., 1869); Eng.
trans. by G.H. Venables (from 2nd ed., 1869); in 1878 a new edition (the 4th) appeared under the editors.h.i.+p of J. Wellhausen, who made extensive alterations and additions; (2) his _Introduction to the New Testament_ (3rd ed., W. Mangold, 1875), Eng. trans. (from 2nd German ed.) by William Urwick (1869, 1870); (3) his _Exposition of the First Three Gospels_ (_Synoptische Erklarung der drei ersten Evangelien_), by H. Holtzmann (1862); (4) his _Lectures on the Apocalypse_ (_Vorlesungen uber die Apokalypse_), (Eng. trans. 1875). Besides these there has also appeared a small volume containing _Lectures on Colossians, Philemon and Ephesians_ (Berlin, 1865). Bleek also contributed many articles to the _Studien und Kritiken_. For further information as to Bleek's life and writings, see Kamphausen's article in Herzog-Hauck, _Realencyklopadie_; Frederic Lichtenberger's _Histoire des idees religieuses en Allemagne_, vol. iii.; Diestel's _Geschichte des Allen Testamentes_ (1869); and T.K. Cheyne's _Founders of Old Testament Criticism_ (1893).
BLEEK, WILHELM HEINRICH IMMANUEL (1827-1875), German philologist, son of Friedrich Bleek, was born in 1827 at Berlin. He studied first at Bonn and afterwards at Berlin, where his attention was directed towards the philological peculiarities of the South African languages. In his doctor's dissertation (Bonn, 1851), _De nominum generibus linguarum Africae Australis_, he endeavoured to show that the Hottentot language was of North African descent. In 1854 his health prevented him accompanying Dr W.B. Baikie in the expedition to the Niger; but in the following year he accompanied Bishop Colenso to Natal, and was enabled to prosecute his researches into the language and customs of the Kaffirs. Towards the close of 1856 he settled at Cape Town, and in 1857 was appointed interpreter by Sir George Grey. In 1859 he was compelled by ill health to visit Europe, and on his return in the following year he was made librarian of the valuable collection of books presented to the colony by Sir George Grey. In 1869 he visited England, where the value of his services was recognized by a pension from the civil list.
He died at Cape Town on the 17th of August 1875. His works, which are of considerable importance for African and Australian philology, consist of the _Vocabulary of the Mozambique Language_ (London, 1856); _Handbook of African, Australian and Polynesian Philology_ (Cape Town and London, 3 vols., 1858-1863); _Comparative Grammar of, the South African Languages_ (vol. i., London, 1869); _Reynard the Fox in South Africa, or Hottentot Fables and Tales_ (London, 1864); _Origin of Language_ (London, 1869).
BLENDE, or SPHALERITE, a naturally occurring zinc sulphide, ZnS, and an important ore of zinc. The name blende was used by G. Agricola in 1546, and is from the German _blenden_, to blind, or deceive, because the mineral resembles lead ore in appearance but contains no lead, and was consequently often rejected as worthless. Sphalerite, introduced by E.F.
Glocker in 1847, has the same meaning ([Greek: sphaleros], deceptive), and so have the miners' terms ”mock ore,” ”false lead,” and ”blackjack.”