HYDRIDES AND CHLORIDES. 13 



selenetted, and telluretted hydrogen, we are able to extract twice 

 the volume of hydrogen, and from equal bulks of phosphoretted, 

 arsenetted, and antimonetted hydrogen we are able to extract 

 three times the volume of hydrogen that can be got from the 

 same bulk of hydrochloric acid, as indicated in the table. 



Monhydrides Dihydrides Trihydrides 



HF H a O H 3 tf 



HC1 H,S H 3 P 



HBr H a Se H 3 As 



HI H,Te H 3 Sb 



(12.) We find, moreover, that chlorine is capable not only of 

 uniting with hydrogen in the proportion of volume to volume, 

 but also of replacing hydrogen in the same ratio in a great 

 variety of compounds. Indeed, we may consider the comparable 

 molecules of free chlorine C1C1, and of hydrochloric acid HC1, to 

 be derived from the molecule of free hydrogen HH, by a dis- 

 placement of two atoms, and of one atom, of hydrogen respec- 

 tively, by equivalent quantities of chlorine. Accordingly we are 

 acquainted with chlorides corresponding to all the pre- considered 

 hydrides, C1C1 and C1I corresponding to HC1 and HI ; C1 2 O and 

 C1 2 S corresponding to H 2 O and H 2 S ; and C1 3 N and C1 3 P corre- 

 sponding to H 3 N and H 3 P, &c.; and these chlorides when in the 

 gaseous state are found to have exactly the same bulk as their 

 corresponding hydrides. Thus, from two litres of oxide of chlorine 

 C1 2 O, we are able to extract one litre of oxygen and two litres of 

 chlorine, just as from two litres of oxide of hydrogen H 2 O, we 

 are able to extract one litre of oxygen and two litres of hydrogen. 



Monochlorides Bichlorides Trichlorides 



C1C1 Cl a O C1 3 N 



C1I C1 3 S C1 3 P 



CINa Cl a Zn C1 3 A1 



C1K Cl.Ca Cl 3 Au 



ClAg Cl,Hg Cl 3 Bi 



(13.) The metals do not, as a rule, combine with hydrogen, 

 ^<ut their chlorides, as shown in the above table, may be divided 



