AND AGRICULTURE. 25 



with alkalies, it forms salts. It is so acrid that 

 it burns or destroys wherever it drops upon 

 organic substances. It is composed of sulphur 

 and oxygen. Combining with water, it gives 

 out a very intense heat, often breaking the ves- 

 sel in which the mixture is incautiously made. 

 [See Appendix, 13.] 



PHOSPHORIC ACID is oxygen combined 

 Fig. 9. with phosphorus. Phos- 



phorus is so very inflamma- 

 ble that it can only be 

 handled with the greatest 

 ( care. It is slowly con- 

 sumed in the air, emitting 

 white fumes ; these fumes 

 are phosphoric acid. You may learn its smell 

 from a lucifer-match, if you just rub it, without 

 setting it on fire. Phosphorus exists, in large 

 quantities, in the bones of animals, and it is pre- 

 pared in very great quantities for the use of 

 match-makers. [See Appendix, 14.] 



All these substances, in different proportions, 



Questions. What does it make with alkalies ? Of what 

 is it composed ? What is phosphoric acid ? Is phosphorus 

 yery inflammable ? How should it be handled ? How may 

 you learn its smell ? In what is it abundantly found ? 



3 





