of Iron, and of some other Subsalts. 407 



coloured solution, which had but little of the well known cha- 

 lybeate taste, and its specific gravity was 1*017; this solution 

 is not decomposed either by the admixture of water, or the 

 application of heat, unless it be evaporated to dryness ; the 

 alkalies readily decompose it, but the ferrocyanate of potash, 

 instead of a deep blue, gives a dark brownish green precipi- 

 tate; when more oxide is added to the acid than it is capable 

 of dissolving, the excess, or a portion of it, combines with the 

 submuriate already formed, and the acid and oxide are totally 

 precipitated, forming another, but an insoluble submuriate of 

 iron. 



One of the most curious properties of the soluble submu- 

 riate, and in which it differs from all other binary salts with 

 which I am acquainted, is its decomposition by an addition , 

 of its acid. To a quantity of the solution which contained 

 nearly 7 grains of peroxide, I put 25 drops of muriatic 

 acid ; it occasioned immediate precipitation, and 3 grains of 

 submuriate were throw r n down : when however the solution 

 is heated with excess of muriatic acid, no precipitation oc- 

 curs. 



To determine the composition of the solution of specific 

 gravity 1*017, a thousand grains of it were boiled with a so- 

 lution of potash ; the precipitated peroxide of iron, after 

 washing and drying, weighed 15*5 grains; the solution from 

 which the oxide had been separated, was saturated with nitric 

 acid, and treated with nitrate of silver, by which 6 grains of 

 chloride were obtained : these experiments were repeated, with 

 very slight variations in the results. 



As 146 grains of chloride of silver are equivalent to 3 7 grains 

 of muriatic acid, 6 denote 1*5 grain as the quantity of acid 

 combined with 15*5 grains of peroxide of iron, consequently 

 37 (one atom) of muriatic acid combine with 382 of peroxide 

 of iron, which divided by 40, the atom of peroxide, shows 

 that one atom of acid is united with 9*5 atoms of peroxide. 

 If however the peroxide had amounted to 16*3 instead of 

 15*5 grains, then the atomic constitution of the salt would 

 have been 1 atom of acid +10 atoms base; and this I am 

 induced to suppose is its real composition ; but it would re- 

 quire an extremely nice adjustment of the constituents to ob- 

 tain it, for, as already stated, any excess of the peroxide of 

 iron decomposes the soluble submuriate. 



The submuriate which I have now described, is remark- 

 able on several accounts ; as far as I know, it is the only sub- 

 salt which is largely soluble in water, except the subacetate 

 of lead ; nor do I remember any one which contains so small 

 an atomic proportion of acid ; there is not, perhaps, any other 



binary 



