476 PRINCIPLES OF CHEMISTRY 



thing, yield two fresh salts which are both much more stable ; one 

 contains more oxygen than MC1O, the other contains none at all. 



3MC1O = MC1O 3 + 2MC1 



hypochlorite chlorate chloride. 



Part of the salt namely, two- thirds of it parts with its oxygen in 

 order to oxidise the remaining third. 36 From an intermediate sub- 

 stance, RX, there proceed two extremes, R and RX 3 , just as from 

 nitrous anhydride there proceed nitric oxide and nitric anhydride (or 

 nitric acid): 3N 2 O :5 =X, > O 5 + 4NO. The resulting salt MC]O 3 cor- 

 responds with chloric acid and potassium chlorate, KC1O 3 . It is 

 evident that a similar salt is obtained directly by the action of chlorine 

 on an alkali if its solution be heated, because RC1O will be first formed, 

 and then RC1O 3 ; for example, 6KHO + 3C1. 2 =KC1O 3 + 5KC1 + 3H 2 O. 

 Chlorates are formed thus ; for instance, potassium chlorate, which is 



that is, it acts like nitric peroxide, NO 2 (giving HNO 5 and HNO.,>), or as a mixed anhydride, 

 ~2C1O 2 + H 2 O = HC1O; + HC1O 2 . The silver salt, AgClOo, is sparingly soluble in water. 

 The investigations of Garzarolli-Thurnlackh and others seem to show that the anhydride 

 CloO 5 does not exist. 



36 Hydrochloric acid, which forms an example of compounds of this kind, is a satu- 

 rated substance which does not combine directly with oxygen, but in which, nevertheless, 

 a considerable quantity of oxj^gen may be inserted between the elements forming it. 

 The same may be observed in a number of other cases. Thus, for instance, oxygen may 

 be added or inserted between the elements, sometimes in considerable quantities, in the 

 saturated hydrocarbons ; for instance, in C 5 H 8 , three atoms of oxygen produce an alcohol, . 

 glycerin or glycerol C 5 H 5 (OH) 5 . We shall meet with similar examples hereafter. This 

 is explained generally by regarding oxygen as a bivalent element that is, as capable of 

 combining with two different elements, such as chlorine, hydrogen, &c. On the basis ot 

 this view, it may be inserted between each pair of combined elements ; the oxygen will 

 then be combined with one of the elements by one of its affinities and with the other 

 element by its other affinity. This view does not, however, express the entire substance 

 of the matter, even when applied to the compounds of chlorine. Hypochlorous acid, 

 HOC1 that is, hydrochloric acid in which one atom of oxygen is inserted is, as we have 

 already seen, a substance of small stability ; it would therefore be expected that on the 

 addition of a fresh quantity of oxygen a still less stable substance would be obtained, 

 because, according to the above view, the chlorine and hydrogen, which form such a 

 stable compound together, are then still further removed from each other. But it appears 

 that chloric and perchloric acid, HC1O 5 and HC1O 4 , are much more stable substances. 

 Furthermore, the addition of oxygen has also its limit, it can only be added to a certain 

 extent. If the above representation were true and not formal, then a limit to the com- 

 bination of oxygen could not be looked for, and the more it entered into one uninter- 

 rupted chain the more stable would be the resultant compound. But not more than four 

 atoms of oxygen can be added to hydrogen sulphide, nor to hydrochloric acid, nor to 

 hydrogen phosphide. This peculiarity must lie in the properties of oxygen itself; fom 

 atoms of oxygen seem to have the power of forming a kind of radicle which retains two 

 or several atoms of different other substances for example, chlorine and hydrogen, 

 hydrogen and sulphur, sodium and manganese, phosphorus and metals, &c., forming 

 comparatively stable compounds, NaClO 4 , Na 2 SO 4 , NaMnO 4 , Na.-,PO 4 , &c. See Chapter X 

 Note 1. 



