92 APPENDIX. 



14. Ignite a very small piece of phosphorus in the 

 air ; the white fumes are phosphoric acid. Fill a saucer 

 with water, let a little piece of cork float upon it ; place 

 upon the cork a minute piece of phosphorus, ignite it, 

 and invert over it a large tumbler-glass, or a wide-mouth 

 glass bottle. It is at once filled with dense white fumes, 

 which are phosphoric acid. After a while the fumes 

 disappear, the water has dissolved the phosphoric acid, 

 and the glass only contains the nitrogen which entered 

 into the composition of the air. Phosphorus must be 

 used very cautiously, and always cut under water ; and 

 it should never be handled, as the heat of the skin is 

 sufficient to ignite it. It should be always taken up 

 with a pair of tweezers, or small forceps. 



15. Put a few pieces of limestone, or of the common 

 soda of the shops, into a tall glass (Fig. 2) , and pour 

 thereon a little dilute muriatic acid. Effervescence com- 

 mences with the evolution of carbonic acid gas. Put 

 into the glass an ignited taper ; it is extinguished, but 

 the gas is not inflamed like hydrogen. Then make the 

 gas hi a Florence flask (Fig. 6) , by the introduction of 

 the lime and dilute acid, and collect it in bottles in the 

 same way as chlorine was collected, because it is much 

 heavier than the atmosphere. Put the lighted taper 

 into an empty glass (Fig. 10) , and pour upon it car- 

 bonic acid gas from a bottle or another glass. The ta- 

 per is extinguished, as though water had been poured 

 upon it, instead of an invisible gas. Light a common 

 candle (Fig. 11) and pour upon it the gas contained in 

 an apparently empty tumbler ; the flame of the candle 



