OXYDS. 145 



possess ; — by their combustibility, their solubility in fluids, 

 their combinations with various substances, and by their 

 union with each other, whereby compounds or alloys are 

 formed, extremely useful in a variety of arts, manufactures, 

 and other requisites of life. By combining them with oxy- 

 gen we can invest them with neio properties, and are ena- 

 bled to employ these to promote the progress of the fine arts, 

 by imitating the master-pieces of creation in the production 

 of artificial salts, gems, and crystals, of every colour and of 

 every shade. 



Questions. — 1. What are the simple combustibles? 2. What is 

 said of phosphorus combined with hydrogen gas ? 3. What is carbu- 

 retted hydrogen gas ? 4. Wliat do miners call it ? 5. To what use 

 may it be applied ? 6. What is phosphorus ? 7. What experiments 

 may be performed with it ? 8. How may carbon be obtained in the 

 state of charcoal ? 9. What is said of carbon with regard to vegeta- 

 bles, sugar, wax, &c. 10. What is said of its combinations with iron .> 

 11. In what slate are metals generally found .' 12. What is said of 

 the utility of metals .'' [Note. Chlorine (oxymuriatic acid,) boron 

 and fluorine (the bases of the boric and fluoric acids,) and a substance 

 of recent discovery, called iodine, have lately been added to the list 

 of simple substances, (see Appendix.) Iodine and Chlorine are capa- 

 ble of forming distinct and peculiar acids by combination with Hydro- 

 gen. They form various other compounds, such as Iodides, Chlori- 

 des : lodates, Chlorates ; lodurets, Chlorurets, &g. 



LESSON QQ. 



Oxyds and Combustion. 



As oxygen can combine in different proportions with the same sim- 

 ple substance, the products have been designated by the names 

 oTprotoxyd, dtutoxyd, or tritoxyd, according as the oxygen en- 

 tered into it, in one, two, or three proportions ; and that has 

 been called peroxyd, which was most oxydated, or oxydized. 



Retort', see description of fig. 48, in Appendix. 



Any metal or combustible body which is combined with 

 less oxygen than is sufficient to render it acid, is usually 

 called an oxyd. Whenever a substance is converted into 

 an oxyd, we say it is oxydized; but if it becomes an acid by 

 its union with oxygen, we say it is oxygenized. The mine- 

 ral, the animal, and the vegetable kingdoms, all furnish mat- 

 ters which are convertible into oxyds, by an union with 

 oxygen. Metallic oxyds are formed in several ways, the chief 

 13 



