New York Agricultural Experiment Station. 45 



pliosphate of alumina and iron. Calcium phosphate or phosphate 

 of lime is found in some minerals and in the bones of animals. 



(<?) Importance of Phosphorus Compounds. — The phosphates, 

 like the nitrates, are found everywhere in the soil and are of great 

 value in their relations to plants. The phosphates found in the 

 bones are taken into the animal body in the food. All plants used 

 as food contain small quantities of phosphorus compounds which 

 they get from the soil. The phosphates taken into the body are 

 partly given off in the excrement and urine. 



Sulphur. — (a) Occurrence. — Sulphur uncombined with other 

 •elements, is found near volcanoes. Combined with other elements, 

 sulphur is found in a great many minerals. Sulphur is also found 

 in vegetable and animal product^, combined with the elements 

 ■carbon, hydrogen and nitrogen. The properties of the element 

 sulphur are too well known to need any description. 



(Z*) Compounds. — AVhen sulphur is combined with hydrogen 

 and oxygen in certain proportions it makes sulphnric acid, com- 

 monly called oil of vitrol. When the hydrogen of sulphuric acid 

 has its place taken by any metal, a sulphate is formed. For example, 

 when the metal potassium takes the place of the hydrogen of the 

 sulphuric acid, a salt is formed known as i^otasium sulphate, com- 

 monly called sidpihate of p>otash', from sulphuric acid and the metal 

 calcium is formed the salt calcium sulphate, commonly known as 

 mdp>liate of lime. 



Chlorine. — {a) Description. — Chlorine, when not combined 

 with other elements, is a greenish-yellow gas, having a very suffocat- 

 ing odor. The gas is very poisonous and has very active chemical 

 power. 



(5) Occurrence. — Uncombined chlorine is never found in nature. 

 We commonly know chlorine only in its compounds. Chlorine 

 combined with hydrogen forms hydrochloric or muriatic acid. Chlo- 

 rine combined with any metal forms <?/?/c»/'iV7i'^.s commonly known also 

 as muriates. For example, chlorine combined with the metal soditim, 

 forms a compound which is called sodium chloride or chloride of 

 sodium, or muriate of soda ; and this sodium chloride is the common 

 salt familiar to us in every -day experience. Chlorine combined 

 with the WLQi-A potassiuin for am potassium chloride commonly called 

 nyiuriate of potash. 



Silicon. — Occurrence. — Silicon, next to oxygen, is the most abun- 

 dant clement in nature. It does not occur uncombined with other 



