116 



FUEL. 



cokes, have, in many respects, the same 

 properties as charcoal of wood; as kin- 

 dling mure readily in furnaces than when 

 they are not charred, and not emitting 

 watery, or other gross smoke, while they 

 hurn. This sort of charcoal is even 

 greatly superior to the other in some 

 properties. It is a much stronger-fuel, 

 or contains the combustible matter in 

 greater quantity, or in a more condensed 

 state. It is, therefore, consumed much 

 mote slowly on all occasions, and parti- 

 cularly when employed for producing 

 intense melting heats. The only incon- 

 veniences that attend it are, as it con- 

 sumes, it leaves much more ashes than the 

 other, and these much heavier too, which 

 are, therefore, liable to collect in such 

 quantity as to obstruct the free passage of 

 air through the fire ; and further, that 

 when the heat is very intense, these ashes 

 are disposed to melt or vitrify into a 

 tenacious, drossy substance, which clogs 

 the grate, the sides of the furnace, and the 

 vessels. This last inconvenience is only 

 troublesome, however, when the heat re- 

 quired is very intense. 



In ordinary heat, the ashes do not 

 melt, and though they are more copious 

 and heavy than those of charcoal of wood, 

 they seldom choke up the fire considera- 

 bly, unless the bars of the grate be too 

 close together. This fuel, therefore, is 

 preferable, in most cases, to the charcoal 

 of wood, on account of its burning much 

 longer, or giving much more heat before 

 it is consumed. The heat produced by 

 equal quantities, by weight, of pit-coal, 

 wood-charcoal, and wood itself, is nearly 

 in proportion of 5, 4, and 3. The reason 

 why both these kinds of charcoal are 

 preferred, on most occasions, in experi- 

 mental chemistry, to crude wood, or 

 fossil coal, from which they are produc- 

 ed, is, that the crude fuels are deprived, 

 by charring, of a considerable quantity of 

 water, or some other volatile principles 

 which are evaporated during the process 

 of charring, in the form of sooty smoke 

 or flame. 



These volatile parts, while they re- 

 main in the fuel, make it unfit (or less fit) 

 for many purposes in chemistry. For, 

 besides obstructing the vents with sooty 

 matter, they require much heat to evapo- 



rate them; and therefore the heat of the 

 furnace, in which they are burned, is much 

 diminished and wasted by every addition 

 of fresh fuel, until the fresh fuel is com- 

 pletely inflamed, and restores the heat to 

 its former strength. But these great and 

 sudden variations of the heat of a furnace 

 are quite inconvehient in most chemical 

 processes. 



In the greater number of chemical opera- 

 tions, therefore, it is much more conve- 

 nient to use charred fuel, than the same 

 fuel in its natural state. It is proper to 

 be on our guard against the dangerous 

 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 common 

 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 seem to require a 

 little attention, 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, insensible of all about him, and. 

 breathes strong, snoring as in an apoplexy. 

 If the person is alarmed in time, and 

 escapes in the open air, he is commonly 

 seized with a violent headache, 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 suff'usion over the face and 

 neck, and every indication of an oppres- 

 sion of the brain, by this accumulation of 

 blood. The most successful treatment is, 

 to take off' a quantity of blood imme- 

 diately, 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, 



