Intelligence and Miscellaneous Articles, 325 



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White Indigo. — M. Dumas analysed the white matter into which 

 indigo changes when exposed to the action of alkalis and disoxy- 

 genizing bodies; he found the composition the same as indigo, with 

 the difference that the white indigo contains nearly two atoms more 

 hydrogen. This makes it a hydruret of indigo, and not a deoxy- 

 genized indigo as is generally admitted. 



Anilic acid. — This name was given by M. Dumas to an acid for- 

 merly called indigotic, and obtained by acting on indigo with nitric 

 acid. This acid has not the same radical as indigo; it is represen- 

 ted by C2« H« AZ^ 0», and is anhydrous. 



Picric acid. — This is the last product of the action of nitric acid 

 on indigo, generally known by the name of Welter's bitter. It is 

 composed, according to M. Dumas, of C^^^ H* hZ^ O'i. 



M. Dumas thinks that an oxide of azote enters into its composi- 

 tion. — Journal de Pharmacie, Jan., 1837. 



( . 



ON SOME OF THE PROPERTIES OF PER-IODIC ACID. 



M. Bengiegser obtains this acid by decomposing the periodate of 

 lead by dilute sulphuric acid and the application of heat, carefully 

 avoiding any excess of sulphuric acid, as it often, when in excess, 

 altogether prevents tiie crystallization of the per- iodic acid. When 

 the decomposition is effected, and as soon as the precipitate is de- 

 posited, the solution must be poured off, as, by filtration, even at 

 common temperatures, the acid is apt to be decomposed into iodic 

 acid J this solution is then to be evaporated at a gentle heat until it 

 is completely dry and crystallized. 



This acid is colourless, and its crystalline form appears to be an 

 oblique rhombic prism. In its crystallized state, when heated to 

 266° Fahr., it fuses without decomposing, and by cooling again 

 crystallizes; at 324?° Fahr. it loses its water of crystallization, and 

 at about 370° Fahr. it is decomposed into iodic acid, with a rapid 

 disengagement of oxygen gas. This acid is deliquescent, but may 

 be kept solid over sulphuric acid. The crystallized acid is soluble 

 in alcohol and aether, and the solutions diluted seem to suffer no 

 change by ebullition. An aqueous solution of this acid heated with 

 phosphorus forms oxide of phosphorus and phosphoric acid. The 

 crystallized acid, heated with phosphorus, explodes violently, with 

 the formation of oxide of phosphorus. In both cases the acid is 

 completely deprived of its oxygen, and its iodine is set free. The 

 aqueous solution of the acid e.xerts no action upon sulphur, even 

 when they are boiled together. The action of per-iodic on the tar- 

 taric, formic, oxalic, and acetic acids is analogous to that exerted by 

 iodic acid on these bodies, carbonic acid being formed and iodine set 

 at liberty. 



Most of the metals are oxidized by an aqueous solution of per-iodic 

 acid. At common temperatures it acts on zinc filings, and, when 

 excess of zinc is employed, the acid is completely reduced, giving 

 rise to iodine and oxide of zinc. With copper filings it forms iodate 

 of copper, which is precipitated in white flocks. Iron is converted 



