468 Intelligence and Miscellaneous Articles. 



fectly explains the considerable increase of weight which is found 

 when the xyloidine is precipitated by water immediately after the 

 disappearance of the starch in the nitric acid. As an excess of nitric 

 acid converts the xyloidine into a very soluble substance, which is the 

 new acid above-mentioned, it explains the different result obtained 

 by M. Braconnot, who procured an equal weight of xyloidine from a 

 given weight of starch, which according to M. Pelouze was occasioned 

 by the decomposition of a portion of it ; by long delaying the precipi- 

 tation, not the slightest trace of xyloidine is obtainable. 



When the mixture of acid and starch, instead of being allowed to 

 remain by itself, is boiled, the starch is decomposed in a few minutes, 

 and converted into a deliquescent acid, which is obtained pure and 

 in a large quantity by evaporation in a water bath. This acid con- 

 tains no azote ; it has some resemblance to oxalhydric acid (nitro- 

 saccharic acid) but the composition is different. A moderate heat 

 converts it into another acid of a black colour, which is soluble in 

 water, and susceptible of reconversion by nitric acid into the white 

 acid from which it is derived. 



Boiling concentrated nitric acid attacks it with the greatest diffi- 

 culty. When cold it slowly changes it into oxalic acid without pro- 

 ducing any carbonic acid. Thus by slow oxidizement, determined 

 by the use of a proper quantity of nitric acid, the starch is success- 

 ively converted into xyloidine, deliquescent acid, and oxalic acid, 

 without the carbon suffering the displacement of the other elements 

 of these substances. These curious reactions go on spontaneously 

 in the cold, or in close vessels. 



It has been stated that the xyloidine results from the combination 

 of the starch with the elements of nitric acid. It is a kind of salt 

 in which starch acts the part of base to the nitric acid. It is very 

 combustible ; at 236° Fahr. it takes fire and burns vividly, leaving 

 but little residue. This property led the author to an experiment 

 which appears susceptible of several applications, particularly in ar- 

 tillery. When paper is immersed in nitric acid of sp. gr. 1'5, and 

 left there time enough to be penetrated by the acid, or about two 

 or three minutes, on taking it out of the acid and washing it with 

 a great quantity of water, a kind of parchment is obtained, which is 

 impermeable by moisture and extremely combustible : the same 

 happens with cloth made of linen or cotton. — L'Institut, October 18th 

 1838. 



DETERMINATION OF IODINE IN KELP. 



M. Lassaigne remarks that the extraction of iodine from kelp is 

 now so extensively pursued on account of its numerous applications 

 in medicine and the arts, that by several processes employed in dif- 

 ferent manufactures, the whole quantity is extracted from commercial 

 products ; it cannot therefore, he observes, be unimportant to be able 

 to determine by simple and easy means, the proportion of iodine that 

 different products may furnish. 



Several methods may be employed, which are in fact known by all 

 chemists, and often practised by them : thus in precipitating an aque- 

 ous solution of kelp, saturated with nitric or sulphuric acid, by ni- 



