1818.] colouring Constituent of Roses. l - 27 



respect, however, to the red colour of the petals in roses, I have 

 satisfactorily ascertained that this is clue entirely to iron; having 

 obtained iron and in the metallic state, from an infusion of roses in 

 distilled water. In proof of this, I send you a small globule of 

 iron thus obtained ; exhibiting a high degree of metallic lustre 

 when filed, and having all other properties of the metal. The 

 process by which the metal was extracted shall now be relat d ; 

 merely premising that the sort of rose used in these experiments, 

 was that which botanists term rosa gallica, or common red rose. 

 After carefully separating the petals from their calices, the 

 former were placed in a porcelain vessel and covered with wand 

 distilled water which had been previously boiled in a Florence flask. 

 In this state they were suffered to remain for eight hours, after 

 ■which time the infusion was passed through a filter. A few 

 drops of muriatic acid were then added, and afterwards liquid 

 ammonia; when a dark precipitate immediately fell, which, 

 upon the addition of a little more of the precipitant, and 

 agitating the fluid, became of a leaf green colour. Being 

 left for a couple of hours, a considerable subsidence appeared 

 at the bottom of the vessel, which, collected upon a filter, 

 assumed a mud colour, and in this state was left to dry. 

 After being dried, as much of this mud coloured precipitate 

 as could be taken from the filter was placed in a test tube 

 and a little nitro-muriatic acid poured upon it. The acid 

 had been previously proved, and yielded no precipitate or 

 change of colour to prussiated alkali. Aided by a slight degree 

 of heat, it became of a dark chocolate brown colour, and 

 began immediately to act upon the precipitate with violent 

 effervescence ; disengaging a gaseous fluid, which I have not yet 

 examined, and presently recovering its transparency and colour ; 

 appearing only somewhat paler. Distilled water was then 

 added, and being placed over an Argand lamp, the whole of 

 the liquid was evaporated, nearly to dryness. There then 

 re 'named at the bottom of the tube, a muriate of iron, and 

 distilled water being again added, it was dissolved. Prus- 

 siate of potass now threw down a beautiful emerald green 

 precipitate, which, when left to subside, assumed a blue 

 colour ; this being collected on a filter, the remaining liquid 

 after passing the filter exhibited a topaz yellow hue. As the 

 quantity of precipitate collected upon the filter was very small, 

 I made use of an expedient which I have found convenient in 

 experiments upon minute portions of metallic oxides before the 

 gas blow-pipe, when it was necessary to preserve the quantity 

 is much as possible from diminution; namely, that of tearing 

 off the lower point of the filter containing the substance to be 

 examined, and making it up, while in a moist state, into a pellet 

 between the fingers. This pellet was then placed within a cavity 

 in a stick of charcoal and exposed to the flame of a wax candle 

 urged with a common blow-pipe. In this state, fusion, with 

 exceedingly minute globules, became apparent ; and the de- 



