1824.] Scientific Notices — Chemistry. 387 



Iodous acid dissolves iodine, becoming of a deep colour, more 

 dense and tenacious, and having more strongly the odour o 

 iodine. When heated, the iodine partially rises from the iodous 

 acid, but they cannot be separated in this way. 



M. Sementini believes also in an oxide of iodine, and has given 

 the name to the black powder, which is produced by the action 

 of sulphurous acid on iodous acid, and which still contains oxy- 

 gen, but he mentions that this and some other points still require 

 investigation. 



The following are the properties of the iodic and iodous acids, 

 by which a judgment may be formed of their specific difference. 

 Iodic acid is solid, white, without odour, reddening blue, colours, 

 and then destroying them. Volatile at 456° Fahr. with decom- 

 position ; heated with charcoal or sulphur, it is decomposed with 

 detonation. Iodous acid is liquid, yellow, odorous, reddening 

 blue colours, but not destroying them; volatilizing at 112° Fahr. 

 and even at common temperatures without decomposition; 

 heated with sulphur it is decomposed without detonation, and 

 inflames potassium and phosphorus by mere contact. Bib. Univ. 

 xxv. 119. — (Journal of Science.) 



5. Inflammation of a Mixture of Oxygen and Hydrogen under 



Water. 



Every one is acquainted with the oxyhydrogen blowpipe. 

 Mr. Skid more, of New York, has observed that the luminous jet 

 obtained with that instrument may be introduced under water, 

 without being extinguished. The only precaution necessary is 

 to introduce it slowly, that the flame may not be repelled into 

 the receiver. 



The flame viewed underwater is globular. It burns wood, and 

 heats metallic wires to redness. Mr. Skidmore thinks that his 

 observation may be advantageously employed in maritime war- 

 fare. 



6. Advantageous Mode of using Alcohol in Vegetable Analysis. 



MM. H. Petroz and Robinet, in their examination of the fruit 

 of the lilas, treated the decoction of the grains with a large 

 quantity of alcohol gradually added while in the state of a thick 

 6yrup, without reducing it to a further degree of dryness. By 

 this mode the product of the decoction is at once divided into 

 two portions, one soluble in alcohol, the other not. The decoc- 

 tion should not be evaporated to a very thick syrup, for in that 

 case the precipitated matter retains some of the substances 

 which should be taken up by the spirit. The alcohol must 

 be of such a strength as not to be too much weakened by the 

 water remaining in the syrup. — (Journal de Phannacie.) 



2c 2 



