Page:Encyclopædia Britannica, Ninth Edition, v. 3.djvu/841

Rh of very fine soap are dissolved. The solution ia generally boiled ; but before the silk is put into it, the heat must be lowered to about 90 Fahr., and at this temperature it must be kept during the process. The silks are to be hung in the liquor on rods or frames, and left till the gum is suffi ciently destroyed, care being taken to alter their position now and then, so that every part may be exposed to the action of the bath. When perfectly ungummed, they are flexible and of a dull whiteness ; in this state they are to be wrung out to clear them of the soapy water, then well shaken, and put into coarse linen bags, in parcels of from 20 to 30 fl&amp;gt; each. These bags are now to be steeped in a fresh bath, or, as the workmen say, are to be baked. The bath is prepared in a manner and proportion much as before, except that the quantity of soap may be somewhat diminished as the heat is to be increased ; for the silk is now to be boiled for an hour and a half, taking care to keep the bags from sticking to the bottom of the boiler, by frequently stirring them with a stick. For silk that is intended to be dyed, the former steeping in the lukewarm soap-bath is unneces sary, and the boiling only is employed, using a greater quantity of soap in proportion to the fineness of the colour. After boiling the silk is wrung as before, and then washed, and if it is found to be not sufficiently or not uniformly scoured, it must be submitted to a fresh bath. The white silk usually sold has a bluish shade given it by a bath impregnated with litmus or indigo. This is prepared by dissolving a pound and a half of fine soap in about 90 gallons of water, in which a small quantity of litmus or indigo has been diffused. This process gfves to the silk the tints known by the names of &quot; silver white,&quot; &quot; azure white,&quot; and &quot; thread white,&quot; according to the depth of shade which has been imparted. The &quot; China white &quot; tint is given by adding arnotto to the bath instead of indigo. From these processes the silk acquires a tolerably clear white, but the highest degree is given to it by the action of sulphurous acid, the silk being either^ as is usually the case, subjected to the acid in the state of vapour, or im mersed in a solution. At Lyons no soap is used in the tinting process ; but, after being boiled, the silk is washed, wrung dry, sulphured, and then passed through water pro perly blued.

Bees -wax in its raw condition, as it is first melted up from the comb, is a yellowish coloured substance somewhat greasy to the touch, and having a faint honey-like odour. It often contains mechanical impurities, besides traces of honey, and to remove these and discharge the colour the following process is adopted : The wax is broken up into small pieces and melted in a copper boiler, with water sufficient to keep it from burning. When melted it is run into a tub containing hot water, and while in the hot fluid condition the mechanical impurities it may have contained subside to the bottom. From this tub the melted wax flows into a vessel, the bottom of which is perforated with small holes. Through these thin streams of wax are received I on a cylinder kept revolving in water below ; and thus fine threads of solid wax are produced. These are exposed on I moistened sheets to the air and light for some days, during ! which they are occasionally turned and watered. By this exposure the wax loses much of its colour. It is then melted up into solid blocks and left for some time, after which the operations of melting, forming into threads, and bleaching in the light are repeated till it has attained a pure white translucent lustre, is of very firm consistency, and is free from all odour. Yellow wax is also decolorized by treatment with nitric acid, but chlorine, although it bleaches most expeditiously, is not available, as it leaves traces incorporated with the wax, which on burning evolves irritating fumes of hydrochloric acid. Palm oil, used in the manufacture of soap and candles, is bleached by the action of bichromate of potash and acid.

For bleaching generally, but especially for the bleaching of animal fibres and substances, the use of a considerable variety of processes, and of chemicals other than chlorine and sulphur compounds, have from time to time been proposed and to some extent put into operation. To some of these proposals incidental allusion has already been made, and generally their success has not been such as to warrant special notice. Among other substances which have been recommended for scouring wools and silk are feeble solutions of sulphides of sodium and of potassium, or aluminates of these alkalies, the cyanide of potassium, and a mixture of common salt and oxalic acid. The alkaline permanganates have also been frequently regarded as hopeful bleaching chemicals ; and a few years ago the permanganate of potash was introduced and used by MM. Tessie&quot; du Motay and Mare&quot;chal, who, in connection with the permanganate, used a solution of the peroxide of hydrogen. To this latter substance a peculiar bleaching application has recently been given. Under the name of golden hair water, or auricome, a liquid is sold by hair-dressers which is found to hold in solution a large percentage of peroxide of hydrogen. The use of this solution gives to the hair the brilliant golden yellow tinge which has come to be regarded as a highly fashionable colour. Other applications of this powerful oxidizing and re ducing agent have been suggested by its toilet use, and it has been employed for the bleaching of ornamental feathers, hair, &c. Doubtless, if it could be prepared in stable solution at moderate price it would be found extensively useful in bleaching and other industrial applications. It has also long been hoped that a means of applying ozone as a direct bleaching agent might be devised, but hitherto little success has been attained in this direction. In Germany ivory is bleached by steeping it a week in light naphtha or other volatile oil, and exposing it thereafter to the air and sunlight, by which the atmo spheric oxygen becomes ozonized in contact with the ivory and thus whitens it.  

 BLEEK,, one of the greatest Biblical scholars that Germany has produced in modern times, was born on the 4th July 1793, at Alirensbok, in Holstein, a village near Liibeck. While attending the elementary school there, he gave evidence of such ability that his father sent him, after he had acquired some knowledge of Latin and Greek, in his sixteenth year, to the gymnasium at Liibeck, where he spent three years, and there imbibed so great a love for the languages of antiquity, that he abandoned the idea of a legal career, which he had once entertained, and resolved to devote himself to the study of theology. After spending some time at the University of Kiel, he repaired to Berlin, and there, from 1814 to 1817, enjoyed the instructions of of these distinguished men, especially of the last named, exercised a decisive influence upon the whole of his after life. So highly were his merits appreciated by his pro fessors Schleiermacher was accustomed to say of Bleek that he possessed a special cJiarisma for the science of &quot; Introduction &quot; that in 1818, after he had passed the 
 * De Wette, Xeander, and Schleiermacher. The teaching