132 Transactions of the American Institute. 



very simple gas Inirner, known under tlie name of the Bimsen burner. 

 The ordinary street gas is here consumed, and heat is the result. If 

 I close the lateral apertures (illustrating) light is the consequence. 

 IIow do I change heat into light? I must first have chemical action ; 

 and such was the result of the union of the primordial elements. 

 Thej combined, and light was the consequence. And it requires 

 a certain adroit arrangement of those elements in order that w^e may 

 produce it. By shutting oif the access of air below, the flame of the 

 Bunsen burner becomes luminous. The same materials are burned, 

 but they are burned in a different way. Here is a jar containing a 

 gas known as chlorine. I excite chemical action with powered 

 antimony, and produce light. A solid body is here heated to develop 

 chemical action, and you see tlie result. In another jar of the same 

 substance I place phosj)horus, and it burns without liglit ; but, 

 bringing it into the open air, it produces a brilliant light. In this 

 very flame I will sprinkle these little particles of iron, a solid body, 

 and you remark that instead of simply heat, light is the result. In 

 order to produce light, we must first evolve heat ; and this we may 

 accomplish by many means. We may accomplish it by the union of 

 such elements as oxygen or chlorine ; with a solid body, or with gas. 

 Here is a bit of phospliorus. I place upon it some particles of iodine, 

 and speedy ignition "results, with a beautiful purple flame. Two solid 

 bodies may^combine, and we may have light as a consequence. In 

 lieu of this, we may employ even ice. I pflace upon this piece of ice 

 a little potassium, and it ignites and is even explosive. We have 

 here^i a jar containing* oxygen gas, and if we place in this 

 some body which is capable of forming a solid residuum, w^e 

 shall obtain a light. There are some fragments of zinc, which, 

 beingMieated and dipped in the oxygen gas, produce a brilliant 

 light* and a ^wliite substance known as the philosopher's wool, 

 h ere we have a solid body rendered incandBscent. If, in lieu of 

 zinc, we take another solid, magnesium, it will give off white fumes, 

 and produce a brilliant light. To produce light, we must not 

 only accomplish the production of heat, but nnist have a solid body 

 glowing at an incandescent point. To demonstrate this in a different 

 form : Here we have a reservoir of oxygen, and another of street gas. 

 If we were to use pure hydrogen it would be still better. By turn- 

 ing on the gases, tliQy produce an intense amount of heat ; but if we 

 dd a solid body, as the particles of iron which have been placed in 

 a cavity in this l)rick, wlien they begin to glow tliey will produce a 



