1872.] Capt. W. A. Ross on Pyrology, or Fire Analysis. 



419 



XIV. " Pyrology, or Fire Analysis." By Capt. W. A. Ross, R. A. 

 Communicated by Prof. Stokes, Sec. R. S. Received May 29, 

 1872. 



1. Pyrology, as distinguished from ordinary blowpipe manipulation, 

 may be described as the art of inducing chemical changes in substances 

 from which their composition* can be concluded, by the scientific applica- 

 tion to them of fire, and the use of acid as well as alkaline fluxes for pur- 

 poses of solution and of separation. 



2. The term "Pyrocone" is used instead of that of "flame," em- 

 ployed by writers on the blowpipe, which last expression is here only 

 applied to flames without a definite shape (vide paragraph 25), both 

 because such a distinction is evidently a more correct phraseology, and 

 because it prevents otherwise unavoidable confusion when both kinds of 

 fire are produced in the same operation. For similar reasons the word 

 "blowpipe," which seems a coarse and inexpressive appellation, equally 

 applicable to a pea-shooter and the tubes of an organ, will be relinquished 

 in these pages for the term " Pyrogene." 



Pyro cones. 



3. Pyrocones are divided into two classes, (a) natural and (b) artificial ; 

 (a) is the shape candle and other flames assume in air when left to them- 

 selves ; (b) is that formed by treating («) artificially as follows : — ■ 



4. On the application of a fine jet of air or breath, such as is impelled by 

 operators with the pyrogene, to one side of the base of the natural p} 7 ro- 

 cone, the unburned gases in the centre are apparently expelled ; the 

 luminous cone, unless the blast is too weak, entirely vanishes, and what 

 now appears is a long solid tongue of blue light, terminating in a point of 

 needle-like fineness with a violet-coloured cone enveloping the apex, and 

 extending, with a more obtuse termination beyond it, to a distance com- 

 mensurate with the strength of the blast. 



5. If we take the natural pyrocone afforded by ignited spirits or other light 

 hydrocarbon producer, and blow into the centre of it with a mouth pyrogene, 

 the jet of which is kept at some distance from one side of the cone, we ob- 

 serve two synaxial pyrocones formed by the blast, the bases of which are 

 contracted or enlarged proportionately with its strength or weakness. If 

 we approach the jet of the pyrogene so as to touch the side of the spirit- 

 lamp pyrocone, and blow with greater violence, the inner or blast cone be- 

 comes invisible from the accelerated movement of the air ; but we must 

 analogically conclude that its basic diameter is contracted, and its length 

 extended proportionately with those changes in the outer or visible 

 pyrocone. 



* In the term composition is included the quantitative as well as qualitative estima- 

 tion. 



VOL. XX. 2 L 



