BLASTING. 



BLEACHING. 



The complete success of this experiment (by which it ii said six 

 months' time and 7000/. were saved to the company) naturally lad to 

 the adoption of similar maun in other like owes. On Much 3, in the 

 same year, a second blast took place, little beyond Round Down Cliff, 

 on a smaller scale than the former, an the man requiring remoTal waa 

 not so bulky ; there were 7000 In*, of gunpowder used, and 50,000 

 cubic yards of chalk dislodged. On April 18 a third blast took place, 

 which consumed 10,000 11 w. of gunpowder. Later in the same year, in 

 October, a fourth blast took place, in which the powder was distributed 

 in twenty-eight distinct parts, deposited in as many separate excavations, 

 and all intended to be exploded simultaneously ; but from some dis- 

 arrangement of the wires, several of the charge* did not explode, and 

 these were fired separately on the following day. 



The success of these really grand operations naturally drew the 

 attention of engineers, both civil and military, to this powerful agent ; 

 and during the subsequent period of sixteen yean, the employment of 

 the method has been very extensive. Mr. Brunei employed electro- 

 blasting in the cliff-works connected with the Smith Devon Railway ; 

 Mr. Rid well, in quarrying rocks near the Wrekin Hill, in Shropshire,. 

 made use of the same agency ; as did Messrs. Kemp in disintegrating 

 a large mass of stone at Rosyth Castle. A small application of the 

 same system occurred at Black Gang Cliff, in the Isle of Wight; and a 

 very Urge one at Seaford, on the Sussex coast. The construction ef 

 Portland Harbour of Refuge (now rapidly advancing) is greatly facili- 

 tated by the occasional employment of electro-blasting. The same 

 mar be said in reference to the great harbour-worka at Holyhend. 

 Indeed, civil engineers now regularly employ this process in their 

 great works of tunneling and excavating through hard rock ; while 

 military engineers are equally ready to avail themselves of it for 

 destroying bridges or defence-ivorks, and naval engineers for blowing 

 up sunken or wrecked ships. The system has been partially adopted 

 in clearing the harbour of Sebastopol of the ships which the Russians 

 purposely sunk there in the autumn of 1854. 



In the professional papers of the Royal Military Engineers much 

 valuable information is given regarding the best modes of blasting 

 rock. In one paper, containing ' Instructions for blasting Rock in the 

 Work* of the River Shannon,' very exact rules are given, of which a 

 few may here be briefly noticed : The charges of powder are not to be 

 regulated so much by the depth of the hole to be bored as by the 

 length of the line of least resistance, or the thickness of the rock to be 

 blasted. Charges of powder, to produce similar proportionate results, 

 ought to be as the cubes of the lines of least resistance. In the larger 

 class of explosions advantage may usually be taken of fissures in the 

 rock, to economise the amount of powder employed. The quantity of 

 powder required to fill a hole one foot in depth varies as follows, 

 according to the diameter of the hole : 



1 inch S'028 ounces 



li 11-304 



2 inches 20-112 .. 



24 U1-I1.; .. 



3 ,, 45240 



One pound of powder loosely poured, but not shaken, will occupy 

 about 30 cubic inches : a cubic foot weighs about 574 ""* When a 

 rock about to be blasted is stratified, and in close beds or seams, the 

 holes should be bored in the direction of the strata ; when unstratified, 

 a tolerably exposed and even face should be prepared, and the holes 

 bored parallel to that face. In small explosions, more powder is com- 

 monly used than is necessary : the best mode has been employed 

 when the report of the explosion is trifling, and the mass lifted and 

 thoroughly fractured without any projection of the stones. For tamp- 

 ing, the best material, as well for efficiency as for safety, is dried clay ; 

 the clay may be rolled into cylindrical pieces of two or three inches 

 diameter, or any other convenient form, and dried at a smith's forge. 

 After the charge and the wadding have been introduced into the 

 hole, an inch or two of the tamping should be simply pressed down, 

 the ramming being used only for the subsequent portion of the 

 tamping ; by thin means fewer accidents will occur than by ramming 

 down the whole of the tamping. 



It may not be amiss here to describe an ingenious raft or float 

 employed by Mr. Casebourne a few years ago in submarine blasting, 

 on tin- works of the Hartlepool West Harbour and Docks. This raft 

 was contrived in consequence of the clay or marl which forni.-.l tin- 

 bed of the channel into the harbour being so hard, at a certain 

 that the ordinary dredging-machine was found to have little or no 

 effect on it. The engineer, to overcome this difficulty, coutrivl i n<>\v 

 apparatus. It consisted of a platform or raft, supported by four legs, 

 on each of which was fastened a rack working into a pinion on the 

 deck or platform, so that the latter could be raised or lowered at 

 pleasure. The working level on the ebb tide was about eight feet 

 above the level of the ground, in which position it remained for about 

 five hours, or five and a half, until the tide flowed again. During this 

 time two seU of boring-irons were in use, working through wooden 

 boxes or tubes. These tools made holes in the day four inches in 

 diameter, and of the necessary depth for receiving a cartridge contain- 

 ing three or four pounds of powder, to which one of Bickford'i fuses 

 was attached, and the hole was then carefully tamped : and when the 

 tide roue to the level of the platform the fuses were lighted, the raft 



being floated away to some distance, to be out of danger when the 

 explosion took place. 



BLAZONRY, the art of delineating figures and devices in their 

 proper colours or metals, on armorial shield* : also used to express the 

 batching of the same, according to their different colours, by the 

 engraven. The etymology of the word is somewhat uncertain, but 

 Jimiiis gives the English to Uaa abroad as its origin, and he is pro- 

 bably right, for the Anglo-Saxon i&n has that meaning, and it ha* 

 been used in that sense by modern English authors. Milton, in his 

 paraphrase of Psalm cxxxvi., I 



T.rt UR blaze his name abroad, 

 For of Gods he it the God. 



The German Uaten and the Anglo-Saxon Uatan, both meaning to blow 

 or sound a horn or trumpet, may have contributed, as it was thus 

 the attendants at a tournament announced the rank and dignities 

 of the combatant*. Mr. Lower, in his ' Curiosities of Heraldry,' says 

 in .- note that there are some who deduce it from the German Moor, 

 a mark ; a derivation we think wholly unfounded. 



Allowing the mere invention to the Germans, says Dallaway, the 

 splendid aid that heraldry receives from the art of blazonry is unques- 

 tionably the property of the French alone. Theirs are the arrangement 

 and combination of tinctures and metals, the variety of figures effected 

 by the geometrical positions of lints, the attitudes of animals, and the 

 grotesque and almost inexplicable delineations of monsters. Dallaway, 

 as well as other writers, considers that the tournaments held with such 

 magnificence towards the end of the 10th century, under the auspices 

 of Hugh Capet, were introductory of the more general usage and 

 assumption of arms. (Compare Dallaway K /m/uiriet m<o tkt Origin tuul 

 Progrett of Me Seitnce of Heraldry in England; Gough's StftiicknU 

 MmutmeHJn of Great Sri tain; Edmondson's Heraldry, pref.) 



BLEACHING is the process by which certain nlml and vegetable 

 products, and especially such as are used as articles of clothing, are 

 rendered white. The principal substances of the animal kingdom 

 which are subjected to the operation of bleaching are wool and silk ; 

 those of vegetable origin are chiefly cotton and flax. These bodies 

 contain a quantity of colouring matter, which though natural to them 

 is not an essential constituent; it appean also that the colouring 

 matter is more readily acted upon by chemical agents, and suffers 

 decomposition with greater facility, than the animal and vegetable 

 matters with which it is mixed. On these accounts it is removed by 

 operations producing little or no injurious effect upon the text 

 durability of the articles from which it is separated ; and thus not . mly 

 is their beauty increased, but they aro fitted for the reception i th. 

 colours of the dyer and the ornamental designs of the calico-printer. 



The process of bleaching is one of unquestionable antiquity, and 

 more especially in Egypt, where white linen was used as clothing. Of 

 the Egyptian processes nothing is known with certainty ; they were 

 probably tedious and imperfect ; consisting perhaps of little more than 

 exposure to air, light, and moisture. (See I'lin. xix. 1, on flax.) 



Down to the reign of George II. the art of bleaching was scarcely 

 known in Great Britain; it being usual to send the brown linen 

 manufactured in Scotland to Holland to be bleached. The Dutch 

 method consisted in steeping the linen for several days in a sohiti 

 potash, which was ]>oured upon it boiling hot ; the cloth was then 

 removed, washed, and afterwards put into wooden vessels containing 

 butter-milk, for nearly a week. This operation being over, the cloth 

 was spread upon grass, and exposed to light, air, and moisture for 

 some months ; the cloth sent from Scotland to Holland was generally 

 kept there for half a year. One of the earliest improvements made in 

 this tedious process was proposed by Dr. Home of Edinburgh, who 

 introduced the use of water acidulated with sulphuric acid, instead of 

 the sour milk previously employed : by this substitution a great 

 saving, especially of time, was effected, for the sulphuric acid was 

 as effectual in one day's application, as the sour milk in six or eight 

 weeks. 



Until the year 1787 little further alteration was made in the procewt 

 of bleaching. But a most important improvement was effected in it in 

 consequence of the discovery by Scheele, a celebrated Swedish chemist, 

 of what he termed dephlogisticated marine acid, about the year 1771: 

 this substance was afterwards called oxymuriatic .-i.-i-l. but i- u,.v. 

 known by the name of chlorine gag. The property which this gas and 

 its solution in water possess of destroying vegetable colours, suggested 

 to Itcrthollet the idea that it might be advantageously >-nn.loyed in 

 bleaching, and might essentially shorten the process. In the year 1785 

 he read a paper before the Academy of Sciences at Paris, which was 

 published in the 'Journal de Physique' of the same year. In tlii- 

 paper ho mentioned that he h.i n bliwhing cloth 



a perfectly successful result: in <h-- following year he published 

 another iipcr on the subject, and showed the exiwriment to Mr. Watt, 

 who first introduced this method of bleaching practically into England. 

 About the same time Mr. Thomas Henry of Manchester was iu 

 engaged on the same subject Indeed, these gentlemen appear to 

 have unreservedly described to each other the progress of th 

 periments : and to them lielongs the chief merit of inti < 

 new mode into the neighbourhood of Glasgow, and into Lancashire. 

 By the application of this method, as much bleaching is as well per- 

 formed in a few hours, and in a space of a hundred yards square, as 



