114 



FUEL. 



rior by as many jets; the diameter of the 

 whole is three and a half inches, the same 

 as the French lamp; it gives the same di- 

 vergence, with a power equal to sixty ar- 

 gands. The French lamp only ten. Mr. 

 Gurney'slampischeaper than the French, 

 in the proportion of twelve to seventeen, 

 taking all wear and tear into account. 

 Oxygen is obtained by heating black 

 oxide of manganese, which is found in 

 large quantities in Cornwall and Devon- 

 shire. London Athcnxum. 



The London Literary Gazette of Feb. 

 23, says, "The cost of oxygen is a great 

 addition to the expense of oil, &c. The 

 value of a pint of oil is about ten pence, 

 which is calculated to burn, say for one 

 hottr, the oxygen required for that mea- 

 sure, and that time in the oxy-lamp would 

 be ten cubic feet, and its value would be 

 twenty pence. Here is an addition of 

 dolible the cost of the oil, and the light 

 cannot be obtained for less than 2*. %\d. 

 But compare this with the other arrange- 

 ments. To produce the same light for 

 the same time, not now taking into con- 

 sideration the form or dimensions of the 

 light (that question being settled) it would 

 take 375 argands,which would consume 2 § 

 pints of oil, and cost 2.9. 6^. The same 

 light in Fresnels would incur a charge of 3^. 

 \\d. Thus it is shown satisfactorily, that in 

 every respect, Gurney's oxy-oil lamp is 

 superior for light-house purposes, to any 

 other ever invented. It possesses, also, 

 many advantages, which our space will 

 not permit us to describe. 



FUEL. 



Doctor Black divides fuels into five 

 classes. The first comprehends the fluid 

 inflammable bodies; the second, peat or 

 turf; the third, charcoal of wood; the 

 fourth, pit-coal charred ; and the fifth, 

 wood, or pit-coal, in a crude state, and 

 capable of yielding a copious and bright 

 flame. The fluid inflammables are con- 

 sidered as distinct from solid, on this ac- 

 count, that they are capable of burning 

 upon a wick, and become in this way the 

 most manageable sources of heat; though, 

 on account of their price, they are never 

 employed for producing it in great quan 



sufiicient. The species which belong to 

 this class are alcohol and different oils. 

 The first of these, alcohol, when pure 

 and free of water, is as convenient and 

 manageable a fuel for producing moderate 

 or gentle heats as can be desired. Its 

 flame is perfectly clean, and free from any 

 kind of soot ; it can easily be made to 

 burn slower or faster, and to produce less 

 or more heat, by changing the size or 

 number of the wicks upon which it burns; 

 for, as long as these are fed with spirit, 

 in a proper manner, they continue to yield 

 flame of precisely the same strength. 



The cotton, or other materials, of which 

 the wick is composed, is not scorched or 

 consumed in the least, because the spirit 

 with which it is constantly soaked is in- 

 capable of becoming hotter than 174° 

 Fahrenheit, which is considerably below 

 the heat of boiling water. It is only the 

 vapor that arises from it which is hotter, 

 and this, too, only in its outer parts, that 

 are most remote from the wick, and where 

 only the combustion is going on, in con- 

 sequence of communication and contact 

 with the air. At the same time, as the 

 alcohol is totally volatile, it does not leave 

 any fixed matter, which by being accu- 

 mulated on the wick, might render it 

 foul, and fill up its pores. 



The wick, therefore, continues to im- 

 bibe the spirit as freely, after some time, 

 as it did at the first. These are qualities 

 of alcohol as a fuel. But these qualities 

 belong only to a spirit that is very pure. 

 If- it be weak, and contain water, the 

 water does not evaporate so fast from the 

 wick as the more spirituous part; and the 

 wick becomes, after some time, so much 

 soaked with water, that it does not im- 

 bibe the spirit properly. The flame be- 

 comes much weaker, or is altogether ex- 

 tinguished. When alcohol is used as a 

 fuel, therefore, it ought to be made as 

 strong or free from water, as possible. 



Oil, although fluid like spirit of wine, 

 and capable of burning in a similar man- 

 ner, is not so convenient in many respects. 

 It is disposed to emit soot; and this, ap- 

 plying itself to the bottom of the vessel 

 exposed to it, and increasing in thickness, 

 forms, by degrees, a soft and spongy me- 

 dium, through which heat is not so free- 



tities, and are only used when a gentle 



degree, or a small quantity of heat, islly and quickly transmitted. It is true, 



