Clifton College Scientific Society. 69 



physical constitution of flame was now entered upon, and the 

 various cones in the ordinary flames, as well as the blowpipe flames, 

 carefully pointed out, and illustrated by diagrams, and the chemi- 

 cal functions of these cones noticed and illustrated by an experi- 

 ment upon oxide of lead. The lecturer next proceeded to the 

 colour of flames, the eflect of heat and cold upon them — as upon 

 carbonic oxide and hydrogen ; and to the different results pro- 

 duced according to the nature of the substances present — as boric 

 acid, strontic, baric, calcic, and cupric chlorides upon alcohol, 

 hydrogen, and the Bunsen flames. 



The theories as to whether in these cases the salts are decora- 

 posed and the elements freed or not ; the spectra of different 

 flames ; the merely relative character of the terms combustible 

 and supporters of combustion, illustrated by hydrogen and oxy- 

 gen, were then considered ; and a few words upon the principles of 

 pyrotechny, with illustrations of mimic lightning, lycopodium, and 

 lightning-paper,* red, green, blue, and white fires, and a short 

 sketch of the history of the art, concluded the experimental part 

 of his paper. He then resumed as follows : — 



Flame, then, has nothing in it of an elemental character, as the 

 ancients thought, but is merely the particles of a gas or vapour 

 rendered incandescent, and is luminous in proportion as there are 

 present solid particles which may act as radiant centres of light. 

 To make it clear to you how it is that a perfectly gaseous and 

 transparent body gives out light upon its ignition, I cannot do 

 better than quote the following from Professor Tyndall's ' Heat as 

 a Mode of Motion.' ' Coal gas is what we call a hydro-carbon ; 

 it consists of hydrogen and carbon in a state of chemical union. 

 We have a surface of tliis compound gas in presence of our air ; 

 we apply heat, and the attractions are instantly so intensified that 

 the gas bursts into flame. The oxygen has choice of two partners, 

 and closes with that for which it has the strongest attraction. It 

 first unites with the hydrogen, and sets the carbon free. Innu- 

 merable solid particles of carbon thus scattered in the midst of 

 the burning hydrogen, are raised to a state of intense incandes- 

 cence ; they become white hot, and mainly to them is the light 

 due. The carbon, however, in due time closes with the oxygen, 

 and becomes carbonic acid ; but in passing from the hydrogen, 

 with which it was first combined, to the oxygen, with which it 

 enters into final union, it exists for a time in the soUd state, and 



* To make lightning-paper, gunpaper is first prepared by soaking bibulous 

 paper for about ten nainutes in a mixture of four parts of strong sulphuric acid 

 and five of fuming nitric acid, and gently drying it ; the gunpaper is then dipped 

 in a solution of either baric, strontic, calcic, cupric, or potassic chlorate, according 

 to the colour required. 



