9D ^f' Richard Phillips on the [Jan. 



7 •fl'here are other considerations which tend to strengthen thfe 

 opinion that the chlorides of iron become muriates by decompos- 

 ing and dissolving in water. If to these solutions we add an 

 alkali as potash or soda, oxide of iron is precipitated. Now we 

 must either admit that oxygen is transferred from the alkaline 

 oxide to the iron, which is a possible case, that the iron pre- 

 -fyiously existed in the state of oxide, or that by some operation 

 ^similar to that which has been called predisposing affinity, the 

 decomposition of water is effected at the moment of the presen- 

 tation of potash to chloride of iron. 



As ammonia contains no oxygen, and as it decomposes solu- 

 tions of iron as readily as potash, the cases are reduced to two, 

 viz. either that the iron exists in the state of oxide, or that it 

 becomes so by the intermediate action of the ammonia. It 

 appears to me that the first is the most probable case, although, 

 as 1 shall presently notice, the latter is a possible one. Among 

 the reasons which may be advanced for supposing the solution 

 tiD contain a muriate are the facts already adverted to of the 

 decomposition of chloride of antimony by water ; another reason 

 is that that there are some acids which form insoluble compounds 

 with the oxide of iron, such as the phosphoric, for example. If 

 then we add a solution of phosphate of soda to a solution of 

 muriate or chloride of iron, phosphate of iron is precipitated, 

 which consists of the acid united to oxide of iron, and we are, 

 therefore, reduced either to admit that the iron exists in the 

 state of oxide, or that chloride of iron decomposes water by the 

 addition of a solution of phosphate of soda, for which there 

 appears to be no sufficient cause, nor do I recollect the occur- 

 rence of any such case. 



The action of water upon the chlorides of potassium, sodium, 

 barium, &c. does not appear to have been more decided upon by 

 chemists than other chlorides Dr. Thomson, as I have already 

 noticed, considers that chloride of barium by solution in water 

 becomes a muriate ; whereas M. Gay-Lussac, in a note to a 

 memoir I have already alluded to, says, " On mixing solutions of 

 chloruret of calcium and sulphate of ammonia nearly in equal 

 volumes, the temperature scarcely rose one degree of Fahrenheit, 

 though such a quantity of sulpliate of lime was formed that the 

 whole mixture became soHd. The solution of chloruret of barium 

 treated in the same way produced an elevation of about 6*3°. 

 From these it would seem that in the solution of chloruret of 

 calcium, the metal is in the state of an oxide, while in that of 

 4:hloruret of barium the metal is still in the metallic state." With 

 respect to the chloride of barium, I am certainly much more 

 inclined to adopt the opinion of Dr. Thomson than of M. Gay- 

 Lussac ; for it appears to me extremely difficult to discover by 

 what kind of action water is decomposed when sulphate of soda, 

 for example, is added in solution of chloride of barium, and 



