1Mr. Denham Smith on Ferric Acid. The following communications were then read :- .By J. DENHAM SMITH Esq. XC. Note on a paper on Ferric Acid read May 16 1843. 25 Decembe~-4 1843.-The President in the Chair. The following presents were announced since the last meeting :- ‘‘ The Pharmaceutical Journal,” edited by Jacob Bell from the editor. A Specimen of Bitartrate of Potash in Fine Crystals from J. Denham Smith Esq. Mr. Trenham Reekes was elected an Associate Member. T H E paper above referred to which I had the honour of laying before the Society last session* was unfortunately printed before I had proved that two material errors were contained in it. These errors arose partly from the almost invariable presence of manganese in the oxide of iron preci- pitated from the sulphate which I employed,-an hipurity I neither suspected nor guarded against and which usually oc- curs in such minute quantities as to render its detection im- practicable by the ordinary tests ; and partly from the solubi- lity of sesquioxide of iron in potash under certain conditions - a fact noticed by M.Chodnew I-. The first error occurs in pp. 242-3 where it is stated that chlorine gas passed into 6‘ the deep amethystine solution of ferrate of potash keeping the vessel cod during the passage of the gas gives a solution of a lighter colour than the amethystine liquid.” This solu- tion proved to be a very dilute solution of permanganate of potash. I do not however find the intensity of colour altered by the gas and from the permanent nature of this solution I hope eventually to succeed in isolating the potash salt.The second is the more serious error (p. 247) where I an- * See Memoirs vol. i. p. 240. t. Journ. fur Prakt. Chemie Band axviii. D Chem. Soc. Mem. VOL. 11. 26 Dr. Leeson oft fhc Circular Polarization of Light nounced the existence of an oxide of iron forming a green salt with potash; such a salt I now believe does not exist. I pre- pared a quantity of this green solution by boiling ferrate of potash and rapidly filtering the clear green solution; this gradually decomposed and the brown deposit was dissolved in hydrochloric acid affording a yellow solution to which a solutioii of hydrochlorate of ammonia was added and then caustic ammonia ; a small quantity of a reddish-brown floccu- lent precipitate resembling sesquioxide of iron fell ; this col- lected washed and redissolved in hydrochloric acid gave a yellow solution styptic to the taste which diluted and ren- dered as neutral as possible immediately struck the respective colours blue and blood-red with ferrocyanate and sulpho- cyanate of potash evidencing the presence of iron ; the am- moniacal solution was evaporated to expel excess of ammonia and tested with ferrocyanate of potash when the voluminous flesh-coloured precipitate characteristic of manganese was produced potash added to another portion of this ammo- niacal solution gave on the application of heat a small quan- tity of the dark brown oxide of manganese.Having in the paper referred to satisfied plyself that iron did form a salt with potash and also that the green salt con- tained this metal I was too hastily induced to imagine that the colours of the two solutions alluded to arose from iron ses not uioxide of iron.existence to t x anticipating e sesqui and the teroxide Whether and of an manganese possessing oxide of the in iron the qualities intermediate precipitated of an acid really exists I am at present unable to state but hope to be able to decide this point as well as to communicate some new facts respecting ferric acid and its combinations in a fu- ture paper. 1Mr. Denham Smith on Ferric Acid. 25 Decembe~-4 1843.-The President in the Chair.The following presents were announced since the last meeting :-‘‘ The Pharmaceutical Journal,” edited by Jacob Bell from the A Specimen of Bitartrate of Potash in Fine Crystals from J. Mr. Trenham Reekes was elected an Associate Member. The following communications were then read :-XC. Note on a paper on Ferric Acid read May 16 1843. .By J. DENHAM SMITH Esq. T H E paper above referred to which I had the honour of laying before the Society last session* was unfortunately printed before I had proved that two material errors were contained in it. These errors arose partly from the almost invariable presence of manganese in the oxide of iron preci-pitated from the sulphate which I employed,-an hipurity I neither suspected nor guarded against and which usually oc-curs in such minute quantities as to render its detection im-practicable by the ordinary tests ; and partly from the solubi-lity of sesquioxide of iron in potash under certain conditions, - a fact noticed by M.Chodnew I-. The first error occurs in pp. 242-3 where it is stated that chlorine gas passed into 6‘ the deep amethystine solution of ferrate of potash keeping the vessel cod during the passage of the gas gives a solution of a lighter colour than the amethystine liquid.” This solu-tion proved to be a very dilute solution of permanganate of potash. I do not however find the intensity of colour altered by the gas and from the permanent nature of this solution I hope eventually to succeed in isolating the potash salt. The second is the more serious error (p.247) where I an-editor. Denham Smith Esq. * See Memoirs vol. i. p. 240. t. Journ. fur Prakt. Chemie Band axviii. Chem. Soc. Mem. VOL. 11. 26 Dr. Leeson oft fhc Circular Polarization of Light nounced the existence of an oxide of iron forming a green salt with potash; such a salt I now believe does not exist. I pre-pared a quantity of this green solution by boiling ferrate of potash and rapidly filtering the clear green solution; this gradually decomposed and the brown deposit was dissolved in hydrochloric acid affording a yellow solution to which a solutioii of hydrochlorate of ammonia was added and then caustic ammonia ; a small quantity of a reddish-brown floccu-lent precipitate resembling sesquioxide of iron fell ; this col-lected washed and redissolved in hydrochloric acid gave a yellow solution styptic to the taste which diluted and ren-dered as neutral as possible immediately struck the respective colours blue and blood-red with ferrocyanate and sulpho-cyanate of potash evidencing the presence of iron ; the am-moniacal solution was evaporated to expel excess of ammonia, and tested with ferrocyanate of potash when the voluminous flesh-coloured precipitate characteristic of manganese was produced potash added to another portion of this ammo-niacal solution gave on the application of heat a small quan-tity of the dark brown oxide of manganese.Having in the paper referred to satisfied plyself that iron did form a salt with potash and also that the green salt con-tained this metal I was too hastily induced to imagine that the colours of the two solutions alluded to arose from iron, not anticipating the existence of manganese in the precipitated ses uioxide of iron. Whether an oxide of iron intermediate acid really exists I am at present unable to state but hope to be able to decide this point as well as to communicate some new facts respecting ferric acid and its combinations in a fu-ture paper. to t x e sesqui and teroxide and possessing the qualities of a