142 Intelligence and Miscellaneous Articles. 



of tanned skins, and 5 grammes of flower of sulphur; boil the whole 

 to dryness in a cast iron vessel ; afterwards heat the matter strongly 

 and stir it continually until it softens, taking care that it does not 

 burn ; then having gradually added a small quantity of water, filter it 

 through a coarse cloth, A deep coloured liquor runs through, which 

 may be kept for any length of time in a bottle, but it must be kept 

 well corked ; a single pen-full of this ink is sufficient to write one or 

 two quarto pages, and it possesses all the properties which can be 

 expected in an indestructible ink ; it flows much better than com- 

 mon ink, and does not clog the pen by any substances held in sus- 

 pension ; it also resists the most powerful chemical agents, as will 

 presently appear. 



A strip of paper written upon with this solution, was treated with 

 a boiling solution of potash, and was almost entirely destroyed ; but 

 the portions of paper remaining undestroyed, exhibited the writing 

 perfectly. Paper written upon with the same solution, immersed 

 for an instant in moderately strong sulphuric acid, was partly dis- 

 solved, being converted into a glutinous substance; but upon the 

 undissolved portions, though rendered very thin, the writing re- 

 mained legible. 



Concentrated nitric acid had no effect upon writing with this ink 

 in twenty-four hours, at a temperature below that for the complete 

 destruction of the paper. 



Another piece of paper written upon with the same ink, was 

 immersed for some time in a strong solution of chloride of lime, 

 mixed with muriatic acid, and it was afterwards put into a solution 

 of potash for twenty-four hours ; after this it was boiled to dryness, 

 and then dissolved in water, when only a small portion of paper 

 remained, but upon this the letters were very distinct. 



M. Braconnot is of opinion that this solution may be advanta- 

 geously employed in dyeing chesnut browns upon cotton, linen, and 

 silk, or for darkening other colours. — Annales de Chim. et de Phys. 

 Feb. 1829. 



M. Braconnot has published a notice in the Annales de Ckimie 

 for April, in which he states that this ink is not so indestructible as 

 he at first imagined, for it was destroyed by successive digestions 

 in chlorine and potash. 



PREPAUATION AND COMPOSITION OF SOME BROMIDES, BY 

 M. HENRY, JUN. 

 PERBROBIIDE OF IRON. 

 Take a quantity of pure bromine, and put it into a porcelain cap- 

 sule, containing about twenty times its weight of distilled water,and 

 add gradually, and stirring with a brass rod, iron filings until the 

 liquor ceases to emit bubbles ; it is then to be gently heated, and 

 when it has acquired a greenish tint, it is to be filtered. The solu- 

 tion contains protobromide of iron, which is precipitated white by 

 potash like the protosalts of iron, emitting a very peculiar smell ; 

 then evaporate to dryness by exposure to the air. The residual 

 mass is of an orange red colour; treated with water it does not 

 entirely dissolve, there remain some portions of peroxide of iron 



derived 



