State of the Haloid Salts in Sohitiofi. 359 



reduced, and the iodine oxidated ; thus both in the case of 

 chlorides and of iodides, the acid separated proved to be the 

 hydracid. 



It must, however, always be remembered, that although 

 such production can be readily shown in many cases of ha- 

 loids, it does not necessarily follow that this would hold in all 

 cases. We are of course best prepared to expect it in the 

 case of haloids, of which the constituents have the strongest 

 affinity for oxygen and hydrogen, such as the ordinary ha- 

 loids of the bases of the alkalies and alkaline earths; and ac- 

 cordingly, I showed that it applied to chlorides and iodides of 

 potassium and calcium. But further, it was found to hold 

 good in regard to the ordinary haloids of the common metals, 

 such as zinc. I was prepared, however, to consider it as 

 doubtful what might be the result in regard to the noble 

 metals. Accordingly, when a moderately strong solution of 

 chloride of gold was placed in the tube B *, and connected 

 by asbestus with the tubes A and C, which were filled with 

 distilled water, A being made negative, and C positive by a 

 power of fifty pairs of two-inch plates, no decided indications 

 of the formation of acid were obtained during an hour's action ; 

 for although towards the end there was a slight acid reaction 

 at the positive pole, it was not greater than distilled water itself 

 might have yielded, and there was a trace of alkali at the ne- 

 gative. Before, however, deciding that chloride of gold in 

 solution does not yield to voltaic action, it would be neces- 

 sary to repeat the experiment with a more powerful current, 

 because it may possibly only be a case of more difficult elec- 

 tric resolution. In such cases also atomic constitution may 

 have a considerable, if not the principal influence, on the re- 

 sult. 



Whenever we have obtained a decided instance of the for- 

 mation of acid in the above circumstances, we may conclude, 

 with every probability, that all haloids, of the same nature and 

 atomic constitution, of metals, of equal or more powerful affi- 

 nities, are in the same situation. Thus having verified the 

 rule for chloride of zinc, we may conclude that all proto- 

 chlorides of more electro-positive metals, such as manganese, 

 cerium, magnesium, barium, potassium, Sec, are dissolved as 

 muriates. On the other hand, for the whole series of metals 

 of less powerful affinities, as well as for all haloids of more 

 complex atomic constitution, the matter will still require to 

 be investigated, and I purpose making some further re- 

 searches on the subject. 



* Fig. 2. (p. 243.) 



