FUEL FUENTES. 



331 



gerous nature of the burnt air which arises from 

 charcoal of all kinds. Charcoal burns without 

 visible smoke. The air arising from it appears 

 to the eye as pure and as clear as common air. 

 Hence it is much used by those persons who are 

 studious of neatness and cleanliness in their apart- 

 ments. But this very circumstance should make 

 us more watchful against its effects, which may 

 prove dangerous, in the highest degree, before 

 we are aware of it. The air arising from com- 

 mon crude fuel is, no doubt, as bad, but the 

 smoke renders it disagreeable before it becomes 

 dangerous. The first sensation is a slight sense of 

 weakness : the limbs seems to require a little atten- 

 tion, to prevent falling. A slight giddiness succeeds, 

 accompanied by a feeling of a flush or glow in the 

 face and neck. Soon after the person becomes 

 drowsy, would sit down, but commonly falls on the 

 floor, insensible of all about him, and breathes 

 strong, snoring as in an apoplexy. If the person is 

 alarmed in time, and escapes into the open air, he 

 is commonly seized with a violent headach, which 

 gradually abates. But when the effect is completed, 

 as above described, death very soon ensues, unless 

 relief be obtained. There is usually a foaming at 

 the mouth, a great flush or suffusion over the face 

 and neck, and every indication of an oppression of 

 the brain, by this accumulation of blood. The most 

 successful treatment is, to take off a quantity of blood 

 immediately, and throw cold water on the head 

 repeatedly. A strong stimulus, such as hartshorn, 

 applied to the soles of the feet, has also a very good 

 effect. 



The fifth and last kind of fuel is wood, or fossil 

 coals, in their crude state, which it is proper to 

 distinguish from charcoals of the same substances. 

 The difference consists hi their giving a copious and 

 bright flame, when plenty of air is admitted to them, 

 in consequence of which they must be considered 

 as fuels very different from charcoal, and adapted 

 to different purposes. (See Flame.) Flaming fuel 

 cannot be managed like the charcoals. If little air 

 be admitted, it gives no flame, but sooty vapour, and 

 B diminution of heat. And if much air be admitted, 

 to make those vapours break out into flame, the heat 

 is too violent. These flaming fuels, however, have 

 their particular uses, for which the others are far 

 less proper. For flame, when produced in great 

 quantity, and made to burn violently, by mixing it 

 with a proper quantity of fresh air, by driving it on 

 the subject, and throwing it into whirls and eddies, 

 which mix the air with every part of the hot vapour, 

 gives a most intense heat. This proceeds from the 

 vaporous nature of flame, and the perfect misci- 

 bility of it with the air. As the immediate contact 

 and action of the air are necessary to the burning of 

 every combustible body, so the air, when properly 

 applied, acts with far greater advantage on flame than 

 on the solid and fixed inflammable bodies ; for when 

 air is applied to these last, it can only act on their 

 surface, or the particles of them that are outermost ; 

 whereas, flame being a vapour or elastic fluid, the 

 Bir, by proper contrivances, can be intimately mixed 

 with it, and made to act on every part of it, external 

 and internal, at the same time. The great power 

 of flame, which is the consequence of this, does not 

 appear when we try small quantities of it, and 

 allow it to burn quietly, because the air is not 

 intimately mixed with it, but acts only on the out- 

 Bide, and the quantity of burning matter in the sur- 

 face of a small flame is too small to produce much 

 effect. But when flame is produced in large quantity, 

 and is properly mixed and agitated with air, its power 

 to heat bodies is immensely increased. It is there- , 

 fore peculiarly proper for heating large quantities of 



matter to a violent degree, especially if the contact 

 of solid fuel with such matter is inconvenient. 

 Flaming fuel is used, for this reason, in many oper- 

 ations performed on large quantities of me.tal, or 

 metallic minerals, in the making of glass, and in the 

 baking or burning of all kinds of earthenware. The 

 potter's kiln is a cylindrical cavity, filled from the 

 bottom to the top with columns of wares : the only 

 interstices are those that are left between the 

 columns ; and the flame, when produced in sufficient 

 quantity, is a torrent of liquid fire, constantly flowing 

 up through the whole of the interstices, which heats 

 the whole pile in an equal manner. Flaming fuel is 

 also proper in many works or manufactories, in which 

 much fuel is consumed, as in breweries, distilleries, 

 and the like. In such works, it is evidently worth 

 while to contrive the furnaces so, that heat may be 

 obtained from the volatile parts of the fuel, as well 

 as from the fixed ; for when this is done, less fuel 

 serves the purpose than would otherwise be neces- 

 sary. But this is little attended to, or ill understood, 

 in many of those manufactories. It is not uncommon 

 to see. vast clouds of black smoke and vapour coining 

 out of their vents. Tin's happens in consequence of 

 their throwing too large a quantity of crude fuel into 

 the furnace at once. The heat is not sufficient to 

 inflame it quickly, and the consequence is a great 

 loss of heat. See Laboratory. 



The quantity of watery fluid contained in fuel greatly 

 affects the amount of heat it produces ; much more, 

 indeed, than is commonly admitted in practice. It is a 

 well known law of chemistry, that the evaporation of 

 liquids, or their conversion into steam, consumes, and 

 renders latent, a greater amount of caloric. When 

 green wood, or wet coals, are added to the fire, they 

 abstract from it, by degrees, a sufficient part of its 

 heat, to convert their own sap or moisture into 

 steam, beibre they are capable of being burnt. And 

 as long as any considerable part of this fluid remains 

 unevaporated, the combustion goes on slowly, the fire 

 is dull, and the heat feeble. Green wood commonly 

 contains a third, or more, of its weight of watery 

 fluid, the quantity varying according to die greater or 

 less porosity of different trees. Nothing is further 

 from true economy than to burn green wood, or wet 

 coal, on the supposition that, because they are more 

 durable, they will in the end prove more cheap. 

 It is true, their consumption is less rapid ; but to 

 produce a given amount of heat, a far greater 

 amount of fuel must be consumed. Wood that is 

 dried under cover is better than wood dried in the 

 open air, being more free from decomposition. 



FUENTES, DOM PEDRO HENRIC,DEZ D'AZEVEDO, 

 count of; a general and a statesman, born at 

 Valladolid, 1560. He served his first campaign in 

 Portugal, under the duke of Alva. In 1680, when 

 the duke subjected that kingdom to Philip II., the 

 courage and prudence of Fuentes gained the confi- 

 dence of the general, who gave him a company of 

 lancers. He gained equal distinction in the cam- 

 paigns in the Low Countries under the great Alex- 

 ander Famese. He was afterwards sent on important 

 embassies to different courts. He distinguished 

 himself anew under the marquis Spinola, at the 

 taking of Ostend, in 1606. In the reign of Philip III., 

 he was made governor of Milan, and rendered him- 

 self formidable to the Italian princes and republics, 

 by causing them to feel the superiority of the Spanish 

 power. In 1603, he erected a fortress on a rock at 

 the influx of the Adda into Jake Como, on tl;e 

 borders of the Valteline, called by his name, which 

 was an object of great jealousy to the Orisons. In 

 the war with France, in 1635, so unfortunate for 

 Spain, Fuentes again appeared upon the stage. 

 Spain wished to take advantage of the death of 



