1844.] 



jTHE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



385 



you were probably educated in tlie Palladian school, but I liope yet to 

 see you throw ofl' all its trauiinels, and then take your place as the 

 most correct, as well as the most able, architectural critic of the day. 



Henry Fulton. 

 Clomnore, County Dublin, 

 October, 1844. 



PROFESSOR FARADAY ON HEAT. 



A course of eight Lectures dctiveted at the Royal Institute, 



Lecture VIII., June 8, 1844. 



(Specially reported for this Journal.) 



The nature of flame being of general interest, and intimately connected 

 with the subject, will come under consideration In the present lecture. 



Bodies that undergo combustion may be divided into two kinds, those that 

 burn wiih flame and those that burn without. Cliarcoal burning in oxygen, 

 becomes glowing hot, throws out large or small sparks, but produces no flame. 

 So when charcoal powder or iron fdings are thrown into the flame of a lamp, 

 they scintillate and are consumed, but do not form flame. But tho.se sub- 

 stances which can be converted into vapour, produce flame in burning. Va- 

 pimrs. however, may burn without forming flame. Doebereiner discovered 

 that platinum when finely divided has the property of causing gases to com- 

 bine without flame, though sometimes the heat produced is so great as to 

 make the platinum hot enough to ignite the gases. Light thrown through 

 flame on to a white screen gives a shadow, those flames throwing the darkest 

 sh.adow which give the strongest light for instance, that of camphor. 



Flame is usu.ally of an upright tongue-shaped, but not necessarily so, as it 

 is made so by the upward currents of air which its heat causes. M'hen two 

 gases which combine, such as chlorine and olefiant gases, are burned in a 

 tall glass jar, the air <loes not influence the shape of the flame, and it is then 

 in a flat plate. In looking at the flame of a candle, several distinct [larts are 

 evident ; the wick, ch.arged with the fluid tallow, around and above which is 

 a dark centre, surrounded by the bright luminous part, .and outside of all, a 

 faint blue part. It appears to the eye that it terminates here, but its shadow 

 showed that something belonging to the flame is c-onlinually ascending rapidly 

 from it. This is the column of air which it is heating, mixed with (he gases 

 which it has formed by combustion. The parts of the flame are shown by 

 holding a wire across it, it will be heated the most by the outer part, corres- 

 ponding to the bright lines in the shadow. As Uavy first taught, the dark 

 part in the centre of the flame is nnhurnt gaseous matter, which is continually 

 being consumed at the outer part, .'^ome of this can be drawn from the 

 flame by holding a tube slopingly in it ; this is not smoke, as may be proved 

 by lighting it at the end of the lube, when it will be found to burn like the 

 other part, only with a smaller flame. Hydrogen gas, in burning, gives but 

 little light, and if oxygen is mixed with it, still less. The light which a flame 

 spreads around does not depend, therefore, upon the hydrogen or oxygen, 

 but upon another constituent which is mvariably present in all substances 

 employed for lighting, namely, carbon. In burning the mixture of chlorine 

 and olefiant gases, the latter was completely analyzed, its hydrogen com- 

 bined with the chlorine, and its carbon was deposited in the form of dense 

 smoke, and soot lining the containing vessel. This is what takes place in all 

 cases where enough air is not supplied to flame, its hydrogen combines with 

 the 1 xygen of the air, and its carbon flies oft' as soot, a smoky flame and 

 much less light being the result. A cooling surface being inserted into a 

 flame pri duces the same result ; thus a piece of wire gauze puts out any p.art 

 of a flame, itself becoming smoked. Flame, therefore, is not mere vapour, 

 but a combustion of vapours, in all ordinary cases it is the union, at a high 

 heat, of the vapours with the oxygen of the air. 



That the light produced from flame depends upon the carbon present, is 

 evident from the following experiment :— the flame of hydrogen gas, having 

 scarcely any light, is rendered luminous by throwing into it, by means of a 

 blower, a stream of finely divided charcoal. The ration,ale of the light pro- 

 duced in flame, as given by Davy, is that when gas, oil, coal, wood, or any 

 common combustible is ignited, part of it is convened into vapour, which is 

 continually supplied by the heat of its own flame ; that in combining with 

 the oxygen of the air, its hydrogen burns first, the carbon then from the 

 heat produced, becomes glowing hot and scintillates, and being carried up is 

 brought into contact with the air .and becomes consumed, like the charcoal 

 in the oxy -hydrogen flame. By mixing these vapours or coal gas intimately 

 with air previously to burning, these phenomena are altered, and a blue 

 flame, with scarcely any light, but great heat, is produced. As a general 

 rule, gaseous bodies may be said to give little light and much heat, but solids 

 in combustion generally give much light and little heat. Phosphorus, when 

 burning, produces intense light ; this is due to the solid phosphoric acid which 



is produced becoming inlensely heated, and thus causing light. If this be so, 

 the luminosity of ordinary flames is not so much due to the combustion of 

 the carbon, as to the efli>ct of ils being intensely healed. This may be shown 

 by passing the vapours from burning phosphorus (phosphoric acid) through 

 non-luminous flames, when they become luminous ; the vapours are not con- 

 sumed, and thus might be used over and over again. The same fact is proved 

 by the oxy-hydrogen fl.ame, which by itself gives scarcely any light, but, 

 when lime, magnesia, or other solid bodies which do not consume, are placed 

 in the llame, intense light is the consequence. In Theatres, for the sake of 

 producing sudden bright light to imitate lightning, some powdered substance 

 which is easily vapoured is blown through a tube into a flame, lycopodium is 

 generally employed. .Some gases, when highly heated, give light, such as 

 sulphurous acid but air will not become luminous. 



By the admixture of various substances, flame may be made to assume va- 

 rious colours, producing what is called a monrchromatic lamp. The most 

 perfect of these is the yellow flame produced by burning a mixture of alcohol 

 anil salt. Very curious effects are thus produced, no colour but yellow re- 

 taining its proper hue ; thus, the brilliant red of cinnabar, as in sealing-wax, 

 appears pale yellow ; that of cochineal, as in lake and red morocco, looks 

 black ; as also do the brilliant blues of cobalt and ultramarine; the red of 

 the blood becomes perfectly black, which gives a ghastly hue to the human 

 countenance. 



Combustion of many substances may be carried on at a temperature too 

 low for the production of flame. Thus phosphorus exposed to air, is under- 

 going slow combuslion. producing a luminosity but no flame. A spirit lamp 

 may be fitted w itli a coll of platinum wire, on lighting the lamp so as to heat 

 the coil and carefully extinguish it. the heated wire will retain heat enough 

 to keep the spirit in slow combuslion, itself continuing glowing hot, but 

 without flame, as long as spirit remains in the lamp. Also by pouring a few 

 drops of ether, into a glass jar, and inserting quickly a fine platinum wire 

 healed just below redness, a point will be found in the jar where the ether, 

 combining wilh Ibe air. will keep the wire at redness, and if the beat increase 

 too much, as sometimes happens, the ether will then burn with flame. 



As flame, therefore, requires a certain temperature tor its maintenance, it 

 follows that if a cold good conductor of heat is brought into aflame, it ought 

 to extinguish it. And such is the case ; a ring of iron placed round a very 

 small flame, instantly extinguishes it. and a series of such rings, of which 

 wire gauze may be considered as composed, will not allow the largest flame 

 to pass, owing to the rapidity with which it deprives it of heat. For the 

 knowledge of this fact science is indebted to the researches of .Sir II. Davy, 

 who applied it to the construction of his miner's lamp. An oil lamp entirely 

 enclosed in fine wdre gauze, may be inserted into ajar of explosive or com- 

 bustible gas, which will burn in the inlerior and perhaps extinguish the flame, 

 but it will not be communicated to the exterior. The value of this to the 

 miner, w ho is frequently surrounded by the explosive lire damp, is incalcula- 

 ble, and this simple instrument, which annually prevents (he loss of so many 

 lives, is of itself sufticient to entitle its inventor to the thanks of posterity. 



The lecturer, after thanking his audience for their attention, announced 

 this as the close of the lectures for the present season, and concluded his in- 

 teresling course. 



ON PAPKR HANGINGS. 



// Paper read by Mr. Cowl.'VN, at a Meeting of the Decorative Art Society, 

 held at their Rooms in Davies Street, Grosveuor Stjuare, Oct. 9, 1844. 



Among the many articles of British manufacture that lay claim to our at- 

 tention, few are of more importance than that denominated "Paper Hang- 

 ings," and few have had less of that care and study that it requires; not only 

 is it of importance in a commercial point of view, but it must be considered 

 as a vehicle for the advancement and encouragement of the fine arts of the 

 country. 



The art of ornamenting the w.alls of apartments has been in use from a very 

 distant period ; among the ancient Kgyptians the pictorial representations on 

 the walls of their tombs may lead ns lo suppose that their houses were deco- 

 rated in a similar manner. Among the Greek settlers in the south of Italy 

 decorating the interior of their bouses was paid great attention to ; the ruins 

 of Pompeii and Herculancum attest that the art was highly cultivated there. 

 Some of their designs, though wanting in artistic skill, still possess remark- 

 able brilliancy of colour. The houses of the rich patricians of Italy present 

 numerous specimens of beautiful decorations ; and the ar.abesquesol Raffaelle 

 and the rest of the Roman school are, perhaps, the finest productions of this 

 kind m the world. 



'lapestries, as coverings to walls, were in great use for many centuries in 

 Kurope, and among Ibe Eastern nations it was known at a very remote period 

 Most tasteful and beautiful designs were employed in the manufacture of it,' 



