452 Capt. W. A. Ross on Pyrology, or Fire Analysis. [June 20, 



13. It follows also, from a consideration of fig. 2, and the facts detailed 

 in paragraph 9, that the central portion of the wick or fuel in ordinary 

 pyrological lamps is unutilized ; and in fact, if an oil-lamp be used, having 

 two thin wicks instead of one thick one, and these be slightly pressed apart 

 in the front (as at a, fig. 2), it will be found that a pyrocone of nearly 

 double power will be produced by a similar blast and expenditure of fuel*. 



14. Keeping the assumed fact of the superincumbency of a blast cone, 

 and the consequent solidity of the blue pyrocone underneath in remem- 

 brance, we can readily understand that a roundish object placed in the 

 latter about the centre of its longitudinal axis, which has a diameter equal 

 to or less than that of the pyrocone, will be wholly enveloped by the 

 ignited gas or gases of which the cone is composed, so as to form a kind of 

 bulb or jacket round the front, i. e. that side towards the base of the py- 

 rocone whence the current proceeds. The object is thus apparently pre- 

 served from communication, not only with atmospheric oxygen, but with 

 unignited gas of any kind. Such an envelopment is termed 



The Hydrocarbonous Pyrocone (Symbol H. P.) (fig. 4). 



15. The behaviour of different substances when held steadily in the 

 hydrocarbonous pyrocone causes it to be a synthetical and analytical agent 

 of great value to the pyrologist. Substances of a viscid nature (not salts), 

 as phosphoric or boric acid, become coated, after a few minutes' insertion, 

 with a shining lustrous film having an extraordinary resemblance to a 

 metalf, which, when gold or silver oxides are previously dissolved in the 

 bead, becomes tinged with yellow in the first case, and with a silvery shade 

 in the second, much as alloys of those metals would. This film evidently 

 increases in thickness according to the length of time it is immersed in the 

 hydrocarbonous pyrocone, for after a short immersion the glass is still 

 semitransparent ; but when held a longer time it becomes opaque. 



16. The film thus formed is very hard, being unsusceptible to the point 

 of a penknife. It has no taste, or, if any, that of a metal, while the taste 

 of the oxidized phosphoric acid is sharp and acidulous. After the applica- 

 tion of the tongue, an iridescent tarnish is left like that of sulphur upon 

 silver ; in fact none of these films will stand long exposure to a damp 

 atmosphere. They are so very thin and hard that it seems impossible to re- 

 move any portion from the glass (which remains vitreous in the inside) with 

 the forceps, or even by breaking up the whole bead. 



17. Sulphur in the viscid or red and resinous state is also changed 

 by this treatment to a metallic appearance on its outer surface ; but to pro- 

 duce this reaction, the pyrocone must be very perfect and of an unmodified 

 blue colour, or the sulphur will be at once ignited and burn away. When 



* Messrs. Price and Co. have manufactured, to the order of the writer, pyrological 

 candles with a double wick on this principle. 



f These films are difficult to produce with coal-gas, on account of its general im- 

 purity. Vide paragraph 4. 



