158 Intelligence and Miscella7ieous Articles. 



added chloride of barium to the tincture made with boiling water ; it 

 formed an abundant blue precipitate, and the liquor was entirely de- 

 colorated at the expiration of 24 hours. 



The washed precipitate was of a deep blue colour, and it had in 

 part the properties of a compound of the blue colour of the litmus 

 with barytes. To examine whether tlie dried precipitate contained 

 any sulphate of barytes, it was heated to redness in a platina cru- 

 cible, and moistened with hydrochloric acid, which disengaged sul- 

 phuretted hydrogen gas. Besides this I evaporated the tincture of 

 litmus to dryness, and then heated the residue to redness ; the ashes, 

 besides carbonate of potash and chloride of potassium, contained 

 some sulphate of potash. 



The gradual decomposition of sulphate of potash by the organic 

 matter, and especially the sulphuretted hydrogen which results from 

 it, appeai-s then to be the principal cause of the decoloration of the 

 tincture of litmus ; nevertheless, as in pursuing these experiments I 

 did not discover the presence of sulphuretted hydrogen in the de- 

 colorated tincture, by employing paper moistened with acetate of 

 lead, I became uncertain whether the decoloration was really 

 effected by sulphuretted hydrogen. As however a few drops of an 

 aqueous solution of sulphuretted hydrogen, added to a large quantity 

 of the blue tincture, well stopped in a bottle, were sufficient to de- 

 colorate it in a few days, and as I could not discover in the 

 tincture thus decolorated, any sulphuretted hydrogen, it having been 

 decomposed, I had no longer any doubt that the blue colour of the 

 tincture was destroyed, under all circumstances, by the sulphuretted 

 hydrogen'which is insensibly formed ; thus taking away a part of the 

 oxygen which it afterwards absorbs from the air, and its blue colour 

 returns. After what has been stated, it was impossible to prove the 

 presence of sulphuretted hydrogen in the decolorated tincture, be- 

 cause it is decomposed immediately after its formation. 



The decoloration of the tincture of litmus by means of a few 

 drops of solution of sulphuretted hydrogen, and the recovery of its 

 blue colour by the contact of air, may be repeated a great number of 

 times, without the tincture seeming to undergo any sensible change. 

 When a small quantity of sulphate of lime or sulphate of soda is 

 dissolved in the tincture of litmus, the decoloration begins sooner 

 than with the sulphate of potash which exists in the tincture. 

 Brasilin dissolved in water and stopped in a bottle with sulphuretted 

 hydrogen is also decolorated, but hematin requires a long time for the 

 production of the effect ; and the infusion of the leaves of the 

 Delphinium Ajacis does not undergo any sensible change by sulphur- 

 etted hydrogen, even after the lapse of several weeks. 



Journal de Pharm. Mars 1839. 



ROYAL ACADEMY OF SCIENCES OF PARIS. 

 On Monday, June 24, the Rev. Dr. Buckland, Canon of Christ 

 Church, Professor of Mineralogy and Geology in the University of 

 Oxford, and President of the Geological Society of London, was 



