SIXTH CHAPTER. 



ACIDS, ALKALIES, AND SALTS. 



TN THE **ash" of plants, i. e., in the small residue, 

 left after any vegetable substance — wood, turf 

 leaves, plant fibre, corn cobs, etc. — has been burned in 

 the air, the dissecting (analyzing) chemist discovers 

 a number of substances, those already named as in- 

 organic (soil-derived) elements of plant growth, viz: 

 calcium, chlorine, magnesium, phosphorous, potas- 

 sium, silicon, soda and sulphur. Most of them 

 appear in combination with oxygen, the elementary 



body which readily forms simple com- 

 conJoSdB. Po^ii<is with almost all other elements, 



whenever brought in contact with them. 

 Some of these compounds are acids, others alkalies, 

 others neutral substances. Thus we have the fol- 

 lowing compounds : 



ACIDS : 



Cart)on^ [ ^^^"^i^g carbonic acid. 

 Phosphorus 1 *^™^^g phosphoric acid. 



