FIREPROOF CONSTRUCTION. 



FIREPROOFING. 



90 



what method or in what proportion, with sulphur and with the pitch 

 that is extracted from evergreen firs." One of the properties here 

 stated to belong to naphtha is well known to be, and indeed is, 

 obviously incorrectly ascribed to it ; if it were spontaneously inflam- 

 mable it could not even be collected, and of course could not be 

 mixed with the other ingredients which are named. Whatever may 

 have been the precise nature of the mixture, the account of its 

 effects, from which somewhat of the marvellous must be deducted, is 

 thus strikingly portrayed by Gibbon : " From this mixture, which 

 produced a thick smoke and a loud explosion, proceeded a fierce and 

 obstinate flame, which not only rose in perpendicular ascent, but like- 

 wise burnt with equal vehemence in descent or lateral progress ; instead 

 of being extinguished, it was nourished and quickened by the element 

 of water ; and sand, urine, or vinegar were the only remedies that 

 could damp the fury of thia powerful agent, which was justly denomi- 

 nated by the Greeks the liquid or the maritime fire. For the annoy- 

 ance of the enemy, it was employed with equal effect by sea and by 

 land, in battles or in sieges. It was either poured from the ramparts 

 in large boilers, or launched in red-hot balls of stone and iron, or 

 darted in arrows and javelins, twisted round with flax and tow which 

 had deeply imbibed the inflammable oil. Sometimes it was deposited 

 in fire-ships, the victims and instruments of a more ample revenge, and 

 was most commonly blown through long tubes of copper, which were 

 planted on the prow of a galley, and fancifully shaped into the mouths 

 of savage monsters, that seemed to vomit a stream of liquid and con- 

 suming fire." According to Gibbon, the secret of the Greek fire was 

 confined above 400 years to the Romans of the east ; it was at length 

 either discovered or stolen by the Mohammedans, and in the holy wars 

 of Syria and Egypt they retorted an invention contrived against them- 

 selves on the heads of the Christians. The feu Greyemi, an it is styled 

 by the more early of the French writers, is thus described by Joinville : 

 " It came flying through the air, like a winged long-tailed dragon, 

 about the thickness of a hogshead, with a report of thunder and the 

 velocity of lightning ; and the darkness of the night waa dispelled by 

 this deadly illumination." The use of Greek fire was continued to the 

 middle of the 14th century, when the more efficient employment of 

 gunpowder was substituted. When Ypres was besieged by the Bishop 

 of Norwich in 1383, the garrison defended itself with Greek fire. In a 

 curious paper on the subject of Greek fire by the late Dr. MacCulloch 

 (' Royal Inst. Journal,' vol. xiv.), he remarks that very different things 

 were known by one name ; and he supposes the various projectile 

 means and combustibles employed to have been essentially different. 



FIREPROOF CONSTRUCTION. A building is said to be fire- 

 proof, when it is constructed of incombustible materials; but it is 

 essential to observe, that the danger arising from fire cannot be obviated 

 entirely, even by the most theoretically or practically incombustible 

 construction ; and that consequently it is necessary, not only to observe 

 the ordinary precautions against the destruction by fire of goods kept 

 in such buildings, but also to guard against the effects of extraordinary 

 heat upon the really incombustible materials of which the buildings 

 themselves are formed. In the following notice, therefore, a description 

 will be given of the materials which are the most fitted for the erection 

 of fireproof buildings ; and attention will subsidiarily be called to the 

 danger and inconveniences to which they are exposed in actual practice. 



The conditions required to be fulfilled by the materials to be em- 

 ployed in the erection of fireproof buildings are, that they should not 

 only be unable to burn under the action of ordinary heat ; but that 

 they should also be, as far as possible, non-conductors of heat ; that 

 they should not expand or contract in a marked degree under the 

 influence of changes of temperature, and that they should neither be 

 exposed to fuse, nor to undergo chemical decomposition, when submitted 

 to the action of fire. Of course all woods are excluded from the class 

 of incombustible materials ; but it must be evident, from the enume- 

 ration of the conditions those materials are required to fulfil, that the 

 plasters, cements, limes, some varieties of bricks, and stones, cannot 

 safely be trusted when they are likely to be exposed to great heats ; 

 and that the metals are equally objectionable, because they not only 

 transmit heat readily and alter greatly in their dimensions, but also 

 because sudden and great changes of temperature affect their powers 

 of resistance, and even occasionally cause them to change their form 

 entirely. The plasters and limes used in building owe then- strength 

 to the molecular adhesion originally produced by the solidification 

 which takes place in the course of their hydration, and is subsequently 

 increased by the gradual absorption of carbonic or sulphuric acid gas 

 from the atmosphere. A very low temperature, comparatively, will 

 suffice to destroy this state of combination, and to drive off both the 

 gases and the water of crystallisation to such an extent as to destroy 

 the cohesion of the mass. It is for this reason that the French plaster 

 floor?, or the English concrete floors (whether made with a lime or a 

 cement base), are not able to resist the effects of great fires, although 

 they may be sufficient to render ordinary dwellings practically fireproof ; 

 and for the same reason, brick vaulting itself is not entirely to be 

 relied upon, when the area it covers is great, and there may be large 

 quantities of combustible materials stored beneath it. Of the building 

 stones, it would appear that the sandstones are more adapted for the 

 purposes of fireproof construction than the limestones, because the 

 latter become calcined under great heats ; nevertheless, both limestones 

 and sandstone* are injuriously affected, both by the fire and by the 



water which is so profusely used on the occasions referred to. The 

 sudden contractions produced by the application of cold water cause 

 even granites themselves, about the most infusible of building materials, 

 to fly, as workmen say, or to crack ; and the same danger exists 

 wherever metals are employed, even in a greater degree than when the 

 less rapidly conducting materials are used. 



It follows, from these considerations, that the security offered by 

 any system of fireproof constructions must depend greatly upon the 

 extent of the conflagration which may take place in them. As a fire- 

 proof building ought to be without any communication with sur- 

 rounding buildings, and to have very small openings to the air in the 

 majority of cases, it really acts in the manner of a retort upon the 

 goods which may happen to be in combustion in its interior. It there- 

 fore is essential that the cubical capacity of any isolated incombustible 

 compartment or building should not be large enough to allow a fire to 

 take place which should be able to destroy the physical properties of 

 the building materials employed; and it is to the neglect of this 

 simple precaution that we may attribute the fact that whenever a fire 

 does take place amongst the goods stored in incombustible buildings, 

 the destruction of the goods themselves is entire, and that the stability 

 of the building is so likely to be compromised. Some goods, such as 

 cotton, wool, &c., are liable to spontaneous combustion ; and if such 

 goods should be stored in large quantities in one building, the security 

 afforded by the supposed fireproof charaete of the materials of the 

 latter will too often be found to be fallacious. Some of the most 

 destructive fires have actually taken place in fireproof buildings ; and 

 nothing can be more striking than to observe the unaccountable changes 

 of form produced in the iron, stone, or brick, exposed to the action of 

 large masses of incandescent materials thus enclosed. Cast iron appears 

 to be far more injuriously affected in these cases than wrought iron, 

 especially when it is likely to be suddenly chilled by the cold water 

 pumped upon the burning goods. Wrought iron, however, loses its 

 elasticity when heated, and is exposed to change its form under the 

 action of loads it would otherwise have easily supported. 



These remarks apply especially to warehouses ; but in ordinary 

 house or shop construction it rarely happens that a sufficient quantity 

 of goods is contained in any one compartment of the building to entail 

 any extraordinary danger. If, therefore, the walls of such houses be built 

 of good brick or stone ; if iron be used instead of wood for girders, 

 lintels, bressummers, &c. ; if the roof be entirely of metal, and the 

 floors of either brick- work, tiles in cement, stone landings, or of plaster 

 or concrete ; the houses will be, for all practical purposes, fireproof. 

 These materials are, however, all of them good conductors of heat ; and, 

 as such, they require, in dwellings, to be covered with wood, or some 

 other material which should be able to obviate the unpleasant feeling 

 produced by their being exposed. The danger of the combustion of 

 such woodwork may be materially diminished by the application of a 

 soluble glass to all the exposed surfaces ; and care should be taken 

 that none of the wood runs so far into the solid walls as to affect their 

 stability, either in consequence of its being burnt out, or on account 

 of the chemical changes produced by the heat. The resinous woods 

 being more rapidly inflammable than oak, or the harder woods, .such 

 as mahogany, teak, rosewood, &c., are less fitted for the purposes of 

 lining fireproof structures than are the latter ; and it is perhaps on 

 account of the general use of oak floors in Paris that so few fires occur 

 in that town, in comparison with those which occur in London, where 

 fir floors are almost exclusively used. It may be added, that one of the 

 greatest sources of danger in ordinary house building arises from the 

 use of wooden staircases, which serve to conduct the fire from one floor 

 to another. As a general rule, moreover, it will be found that the 

 thickness of party walls which is requisite to ensure the statical 

 stability of a building will be sufficient to prevent the communication 

 of any ordinary fire from one house to another : provided always that 

 no timbers be allowed to be inserted in such walls, or at least that 

 solid non-combustible materials of at least nine inches in thickness 

 shall always be placed between the ends of the timbers thus let in. 

 Great care should be taken, when artificial methods of warming are 

 adopted, to isolate the timbers or joiners' work from the pipes or 

 passages by which the heat is distributed ; for the effect of the proximity 

 of wood- work to such heat passages is to dessicate the wood thoroughly, 

 and to render it highly inflammable. The same remark would of 

 course apply, mutatis mutandis, to the combustion of gas near wood- 

 work ; and it is desirable in all these cases that a sufficient non- 

 conducting cushion of air should be, as it were, interposed between the 

 source of heat and the wood- work. 



FIREPROOFING. In this article we shall briefly describe three 

 modes of shielding combustible articles from the ravages of fire, under 

 the sub-headings fireproof Repositories, Fireproof Woodwork, and Fire- 

 proof Textile Goods. 



Fireproof Repositories. By this we do not mean houses or buildings, 

 rendered fireproof by peculiar modes of construction ; these are treated 

 in another article. [FIREPROOF BUILDINGS.] We speak of iron cham- 

 bers, coffers, or boxes, for containing valuable property. It was not 

 until the present century that such receptacles were regularly and 

 systematically made. A few may have been constructed as special 

 examples of ingenuity ; but the manufacture had not yet become a 

 regular branch of trade. The old treasure-receptacles were oak chests, 

 secured by one or more locks, or brick or stone closets, with wooden 



