Intelligence and Miscellaneous Articles. '691 



First, the nitric acid added in tlie proportion of yJ^ydth to the 

 sulphuric acid is not useless, as stated by M. Herzog ; for by its 

 influence the series of colours is produced much more readily and 

 sensibly than when it is omitted. M. Marchand states that he was 

 aware that strychnia yielded a fine blue colour by the action of pure 

 sulphuric acid and peroxide of lead only ; but that it is almost im- 

 possible to perceive the red and yellow colours, which are readily 

 perceptible in the conditions described by him : and the author adds 

 that he never said or believed, as supposed by M. Herzog, that 

 strychnia, when placed in the circumstances described, might serve 

 as a reagent for nitric acid. 



As to the substitution of peroxide of manganese for that of lead, 

 the author has only one objection to make, which is that the salts of 

 manganese sometimes possessing a red colour, there can be no cer- 

 tainty that the series of colours obtained belongs properly to the 

 substance supposed to be strychnia, since one of the reagents em- 

 ployed may itself give rise to one of the colours indicated. 



The same is the case with the bichromate of potash recommended 

 by M. Otto. This salt produces by its solution in sulphuric acid a 

 yellow or green colour, and it follows that the series of colours indi- 

 cated by M. Marchand is diminished bj"^ at least one colour, and 

 sometimes by two, the yellow and the red, and consequently the 

 reaction is far from being complete. 



The method of employing M. Marchand's process is that of tritu- 

 rating the strychnia with peroxide of lead and concentrated sulphuric 

 acid containing 1 per cent, of nitric acid ; by this process the colours 

 obtained are blue, becoming rapidly violet, then gradually red, and 

 lastly, after some hours, it assumes a delicate yellow colour. — Journ. 

 deCL Med., Avnl\848. 



ON THE PRESENCE OF SELENIUM IN THE IODIDE OF 

 POTASSIUM. 



M. de Trez, when acting upon a solution of protiodide of mercury 

 and iodide of potassium by acids, perceived a smell of sulphuretted 

 hydrogen during the operation ; he subsequently discovered that the 

 smell arose from hydroselenic acid, the odour of which strongly re- 

 sembles that of hydrosulphuric acid. 



'I'he selenium exists in the iodide of potassium in the state of sele- 

 niate of potash. 'I'o determine the presence of this substance M. de 

 Trez advises an acid to be added to the solution of the iodide, and to 

 receive the gas disengaged in a solution of acetate of lead. The 

 grayish-black precipitate which is formed in this case being col- 

 lected, washed and dried, is to be introduced into a glass tube, the 

 bent extremity of which is to be immersed in a bottle containing 

 distilled water ; through the other end of the tube a current of 

 chlorine gas is to be passed ; as soon as the tube is heated by char- 

 coal, a liquid of a deep yellow colour flows into the receiver ; this is 

 followed by whitish vapours, which condense in the cool part of the 

 tube, and when this is heated the vapours pass into the receiver, and 



