206 SCIENTIFIC AMUSEMENTS. 



therefore must not be held long in the fingers, otherwise it may light 

 and produce painful burns which do not heal readily. If lighted 

 whilst moist it is apt to sputter arid throw out blazing particles, 

 so that to avoid cracking glass jars when burnt inside them it 

 should be dried by lightly pressing in blotting paper. So little 

 heat is requisite to ignite phosphorus in contact with the air that 

 inflammation can generally be brought about by rubbing a knit- 

 ting needle or other piece of metal vigorously with a rough cloth 

 so as to warm it by friction, and then making the warm metal 

 touch the phosphorus. Similarly a test-tube half full of water 

 with a few drops of oil of vitriol dropped in (vide Expt. 98) will 

 become sufficiently warmed by the heat produced on diluting the 

 acid to fire the phosphorus if made to touch it. 



Expt. 235. Luminous Writing. If a stick of phosphorus be 

 held by a towel or pair of tongs and then used to write with on a 

 wall, pencil fashion, the writing will be found to be luminous in 

 the dark ; this arises from the fact that small particles of 

 phosphorus are abraded from the stick and adhere to the surface 

 of the wall, just as blacklead from a pencil ; these particles 

 combine with the oxygen of the air and evolve light in so doing, 

 but are too minute to set up actual flame. 



Expt. 236. Luminous Faces. Olive oil can dissolve a small 

 quantity of phosphorus. To prepare the solution, put a little oil 

 into a test-tube and warm it over the lamp ; drop in a small 

 fragment of phosphorus previously dipped in oil (so that it shall 

 not remain at the surface and take fire), and cork the test-tube, 

 now and then giving it a shake; the oil will soon take into solu- 

 tion some of the phosphorus, so that if a little of the phosphorised 

 oil be rubbed over the face and hands they will become luminous 

 in the dark, for the same reason as the phosphorus writing in the, 

 last experiment, viz., that the phosphorus oxidises, evolving light, 

 but does not take fire owing to the small quantity present. 



Expt. 237. Fenian Fire. When somewhat larger quantities 

 of phosphorus are spread over a considerable surface, the action 

 of oxidation may become sufficiently energetic to loring about 

 actual inflammation. Half fill a small bottle with carbon disul- 

 pliide (a compound of carbon and sulphur) and drop in one or two 

 fragments of phosphorus cut from a stick, each the size of a pea ; 

 these will quickly dissolve.* Shake up the liquid and pour a 

 teaspoonful out on to a sheet of blotting-paper supported by an 



* "Yellow" phosphorus, such as is sold in sticks, requires to be kept under 

 water because of its inflammability ; this variety dissolves freely in carbon di- 

 sulphide ; but there is another form of phosphorus known as "red" or " amor- 

 phous " phosphorus which is insoluble in that fluid ; this form of phosphorus 



