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THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



[Feb. 3, 



Table II. Absorption of Moisture ly Weight. 



PKACTICAL DEDUCTIONS. 



Want of space will not allow me to point out the numerous subjects of 

 practical utility to be derived from the whole series of experiments hitherto 

 detailed for the benefit of architects, engineers, and builders, but I will ven- 

 ure to fill up the remaining sheet with a few deductions that appear most 

 prominent. 



Asphalte stands as the best composition for resisting moisture ; it is a 

 slow conductor of heat, and hence is well adapted for flooring, as in cells of 

 prisons, where economy of heat and dryness, the most important advantages 

 are obtained. Slate will be seen to stand as a very dry substance, but from 

 its quick conducting power (Table I.) it is very unfavourable to flooring 

 where warmth is required; but when the one property is sought for and not 

 the other, as preventing the ascent of moisture up the walls of houses, it is 

 well calculated to be useful by forming a layer in the wall a few inches above 

 the ground. The absorbing power of comniou brick appears very great, 

 being more than one-fifth of its own weight; whereas Mann and Co.'s Stucco 

 paint cement is not greater than ^ of its own weight, and hence more than 

 six times better adapted to resist moisture than brick, therefore the advan- 

 tage to be derived by covering brick houses in exposed situations with this 

 substance is considerable, while Koman cement resists moisture even worse 

 than brick. I wish it to be borne in mind that I only speak of this stucco as 

 regards its power of resisting the transmission of water, being the only pro- 

 perty of it which I have examined. 



Keene's cement and plaster of Paris stand as the warmest substances, there- 

 fore are well adapted to line rooms with, while hair and hme is a remarkably 

 quick conductor, and therefore a cold substance for that purpose. 1 would 

 also draw attention to the fact, that plaster and sand and plaster of Paris 

 (particularly the latter) are admirably calculated to resist the action of fire, 

 while we know, on the other hand, that lath and plaster is about the most 

 combustible material in a house. I can most confidently recommend plaster 

 of Paris and plaster and sand to be employed in surrounding iron chests, or 

 other places which contain valuable property, intended to be protected from 

 lire. If an iron chest be surrounded with six or eight inches in thickness of 

 this substance, I believe it will perfectly preserve papers, &c., from any de- 

 stroying heat in the midst of the burning of our ordinary dwelling houses. 

 I may also point out that Yorkshire flag stone is a very quick conductor, and 

 therefore ill adapted for warm flooring; also that lead which forms the 

 covering of roofs is a remarkably quick conductor, and therefore a great 

 waste of heat is experienced where such covering exists ; hence the third 

 back rooms on ground floors in our London bouses are found to be so cold ; 

 a vast quantity of heat escapes through the leaden roof, and through three 

 of the surrounding walls, which are generally external, and so thin as to 

 allow of a free escape of heat. Such places should be lined with slow con- 

 ductors if warmth is sought for. Touching the practical utility of the 

 specific heat experiments, I may point out, that fire brick absorbs a great 



quantity of heat, and therefore is well adapted to form the hacks of our fire 

 grates, whereas, with iron backs, there is an enormous waste of fuel and 

 heat, at the same time the fire requires constant stirring, and a quick supply 

 of coal to keep it in ; yet, curious to remark, we never enter a bouse, even of 

 the highest order, where iron backs to fire grates are not universally to be 

 seen, while, a back formed of a composition, as that of fire brick, which can 

 be as easily moulded into any desirable shape, would both save fuel, 

 thoroughly warm any apartment, require less stirring, and not go out so 

 soon. 



With regard to the specimens of wood I have examined, it is worth ob- 

 serving that Maulmein teak absorbs much less water than oak wood, in the 

 proportion of 82 to 224, being nearly one-third less; and as the density of 

 woods in their ordinary state bears a strict relation to their porosity or pro- 

 portion of air within their pores, connecting with this, the fact that iron, 

 protected from contact with the atmosphere and water ("being compounds 

 of oxygen) the better it is preserved, may very possibly be the reason assign- 

 able for the truth why iron is preserved considerably longer in Maulmien 

 teak than in oak ; the rtlation of absorption of water with the teak and oak 

 (omitting the decimals) is as 82 of the former to 224 of the latter. The 

 density of all these specimens of wood is here calculated from the state in 

 which they naturally exist, that is, as dry as could be obtained, yet contain- 

 ing an unknown quantity of air and moisture. Mr. Parnell observes " when 

 wood, rendered perfectly dry by the aid of heat, is exposed at common tem- 

 peratures to the atmosphere in its ordinary state of humidity, it re-absorbs 

 a certain proportion of water, varying accordingly to the compactness of the 

 wood, and to the quantity of deliquescent saline matters present." In refer- 

 ence to these two assigned reasons that govern the absorption of water by 

 woods, I would draw attention again to the Maulmien teak in comparison 

 with the beech wood ; the relative specific gravity or density of the former 

 to the latter is as 7442 to 7498, being very nearly equal, yet the absorbing 

 power of the two is very different, being in the proportion of 82 to 185. 

 These facts render it incumbent on rae to recommend it to the attention of 

 sliip-builders. 



By Table II. it will be observed that the two kinds of flag stone, termed 

 Shetland and Caithness, absorb very little moisture; having been previously 

 informed of this property, I was desirous of e.xamining them, and certainly 

 they maintain the character determined from the observation of practical 

 men. Their conducting power for heat 1 had not an opportunity of calcu- 

 lating, but if I might venture an opinion, I suspect they would range like 

 Yorkshire flag stone; if so, they are quick conductors, or cold materials for 

 flaging rooms were warmth is required ; nevertheless, they will be found as 

 valuable materials for arresting the ascent of moisture iu the walls of houses, 

 and speaking from memory I believe the Caithness flag has thus been em- 

 ployed in the north of England with great success. 



The Carrara marbles mentioned are those generally employed in con- 

 structing mantle-pieces; it is curious to observe, though their density is the 

 same, yet the harder specimen absorbed more than twice as much water as 

 the softer marble. 



Portland stone, Bath stone, and the stones employed in erecting the new 

 Houses of Parliament, may be considered as spongy materials for absorbing 

 water; their relative conducting power may be referred to in the first column 

 in Table I. It will also be seen that Napoleon matble is a warmer material 

 than common brick. I mention this to correct the general opinion that 

 brick is a slow conductor, and therefore a greater thickness of that material 

 should be used in forming the walls of our houses ; hence it is that the 

 brick walls so often neither aft'ord protection from the cold of winter nor the 

 heat of summer. 



It will be observed that the specific heats have been compared with water 

 as 1, therefore, if we reflect upon the capacity of water for absorbing heat, 

 it very much exceeds all the substances with which it is compared. Water, 

 therefore, becomes a reservoir for heat upon the surface of the globe; islands 

 being surrounded by this reservoir, are preserved of a more equable tem))e- 

 rature than main lands. 



In reference to the conducting power of malm and stock brick, it will he 

 seen that stock brick is placed twelfth in the scale, and malm brick the six- 

 teenth ; it is. therefore, so much colder as a shield from the weather. From 

 this circumstance I would remark, that when this brick (malm) is used to 

 ease a building (as is now commonly done) the walls should be constructed 

 proportionalily thicker, or we render the house so much colder. The ab- 

 sorbing power also of this brick for heat is very low, being placed third in 

 the scale in Table I. (third column), therefore we may conclude that malm 

 brick is more a substance to please the eye for building than useful as a 

 protection against the escape of heat, and what applies to the escape of heat 

 will bear a similar relation to the protection against the cold of our climate. 



It is curious to observe how low in the scale hair and lime is placed, both 

 as to conduction and capacity for heat. If lead were omitted from the 

 Table it would stand nearly as the quickest conductor and the lowest specific 

 heat, proving that the compound is ill-adapted to line our rooms as far as 

 concerns the preservation of heat. The best property of Roman cement, 

 from these tables, certainly appears to be that of its slow conducting power, 

 and therefore it is much better adajited to encase brick houses than malm 

 brick, and as far as regards their relative absorbing power for moisture, the 

 difl'erence is not very great, being in the relation of (omitting the decimals) 

 133 of the former to 116 of the latter. 



