468 PRINCIPLES OF CHEMISTRY 



As the above-mentioned relation in composition i.e. substitution of 

 Cl by the aqueous residue exists between many chlorine compounds 

 and their corresponding hydrates, and as furthermore some (acid) 

 hydrates are obtained from chlorine compounds by the action of water, 

 for instance, 



PC1 3 + 3H 2 = P(HO) 3 + 3HC1 



Phosphorus TOO*,,. Phosphorous Hydrochloric 



trichloride acid acid 



whilst other chlorine compounds are formed from hydroxides and 

 hydrochloric acid, with the liberation of water, for example, 

 NaHO 4- HC1 = NaCl -f H 2 O 



we endeavour to express this intimate connection between the hydrates 

 and chlorine compounds by calling the latter rMoranhydrides. In 

 general terms, if the hydrate be basic, then, 



M(HO) + HC1 = MCI -H H 2 O 



hydrate hydrochloric acid => chloranhydride * water 



and if the hydrate ROH be acid, then, 



RC1 + H 2 O = R(HO) + HC1 



Chloranhydride -* water = hydrate + hydrochloric acid 



The chloranhydrides MCI corresponding to the bases are evidently 

 metallic chlorides or salts corresponding to HC1. In this manner a 

 distinct equivalency is marked between the compounds of chlorine and 

 the so-called hydroxyl radicle (HO), which is also expressed in the 

 analogy existing between chlorine, C1 2 , and hydrogen peroxide, (H0) 2 . 



As regards the chloranhydrides corresponding to acids and non- 

 metals, they bear but little resemblance to metallic salts. They are 

 nearly all volatile, and have a powerful suffocating smell which irritates 

 the eyes and respiratory organs. They react on water like many 

 anhydrides of the acids, with the evolution of heat and liberation oi 

 hydrochloric acid, forming acid hydrates. For this reason they cannot 

 usually be obtained from hydrates that is, acids by the action of 

 hydrochloric acid, as in that case water would be formed together with 

 them, and water decomposes them, converting them into hydrates. There 

 are many intermediate chlorine compounds between true saline metallic 

 chlorides like sodium chloride and true acid chloranhydrides, just as 

 there are all kinds of transitions' between bases and acids. Acid 

 chloranhydrides are not only obtained from chlorine and non-metals, 

 but also from many lower oxides, by the aid of chlorine. Thus, for 

 example, CO, NO, NO 2 , SO 2 , and other lower oxides which are 

 capable of combining with oxygen may also combine with a corre- 



