202 SCIENTIFIC AMUSEMENTS. 



the melted sulphur ; a stream of blue fire will be thus formed, the 

 sulphur being so readily combustible that when once hot and 

 lighted the flame will not be extinguished even by falling 15 or 

 20 feet through the air; a lighted candle will generally go out 

 when dropped from this height, the rapid motion through the 

 air producing the same extinguishing effect, as a heavy puff of 

 wind from the lungs in " blowing it out." 



If in Expt. 219 the stream of carbon monoxide issuing from a 

 generator be somewhat rapid, or better, if a small bladder or gas- 

 holder be filled with this gas (Expt. 177) and a rapid stream of gas 

 be then expelled again therefrom, it will often be found that the 

 gas will not burn with a steady continuous flame, as the rapidity 

 of the current of gas produces of itself the effect of blowing out. 



Expt. 227. To Bleach Flowers by means of Sulphur 

 Dioxide. The gas produced when sulphur burns in air or 

 oxygen has the power of acting on certain kinds of colouring 

 matter, converting them into colourless substances ; for which 

 reason it is used as a bleaching agent, more especially for straw 

 and some kinds of silk. Burn some sulphur in a jar of oxygen 

 or air, and then place some flowers moistened with water inside 

 (red roses answer well), the colour will in many cases shortly 

 disappear ; with a rose, the tint may to some extent be restored by 

 dipping the bleached flower into water to which one or two drops 

 of sulphuric acid have been added. 



Combination of Gases with Solids or Liquids to form Non- 

 Gaseous Products. When a metal rusts in the air, and especially 

 when a melted metal forms a film of dross on the surface (Expt. 

 15), the action is simply due to combination of the metal with the 

 oxygen of the atmosphere, forming a solid product different from 

 either the metal or the oxygen combined with it. In all such 

 cases there is a greater or less development of heat, according to 

 the intensity of the chemical action and the length of time over 

 which it is spread ; when the action takes place rapidly between 

 materials that react vigorously with one another, the development 

 of heat is frequently very intense, quite comparable in extent with 

 the modes of production of heat above discussed where combustible 

 substances are burnt to gaseous products. Thus when certain 

 metals are heated sufficiently in the air they take fire and bum 

 readily, evolving much light and heat in so doing ; naturally the 

 action becomes more intense Avhen pure oxygen is substituted for 

 air. Certain metals when brought into contact with chlorine do 

 not require any heating at all to bring about vigorous action with 

 production of light and heat. 



Expt. 228. To burn cold Antimony in Chlorine. If powdered 



