Chemical Science. 615 



It is important to wash away all the subchloride, which may be 

 clone by using colourless saturated solutions of the perchloride. It 

 appears probable, from the change of colour, that the first contact of 

 water converts nearly the whole of the perchloride into iodic acid*. 



5. ON THE PRECIPITATION OF THE VEQETO-ALKALIES BY IODIC 

 ACID. (Serullas.) 



On a former occasion M. Serullas shewed that solution of iodic acid, 

 added to solutions of the vegeto- alkaline salts, produced an abundant 

 precipitate of acid iodate. In this way the smallest quantity of a ve- 

 geto-alkali may be shown by this acid, or by a solution of perchloride 

 of iodine, because of the iodic acid there present. The sensibility is 

 so great that the acid may be considered in this respect as one of 

 the most delicate tests which chemists possess : the hundredth part 

 of a grain of quinia or cinchonia, dissolved in several thousand times 

 its weight of alcohol, may in this way be precipitated, and the preci- 

 pitate quickly collected. The iodic acid should be so dilute as not to 

 be precipitated itself by the alcohol ; that is always the case when so- 

 lution of the perchloride of iodine is used. All the vegeto-alkalies 

 are not equally evident to the test, but the least sensible is discovered 

 when one-fifth of a grain is present. 



Great excess of the acid is required in these experiments; it 

 should, therefore, be added by drops. From this circumstance, the 

 alkalies are no test of iodic acid. M. Serullas hopes to found on these 

 effects a process for trying the strength of Peruvian bark. 



The iodine with which the acid is formed ought to be quite pure, 

 and the alcohol also, with which the iodic acid is washed, ought to be 

 purified ; the latter by mixture with a few drops of sulphuric acid, and 

 distillation to remove lime ; the former by using iodine precipitated 

 from its alcoholic solution by water. 



The precipitates formed by iodic acid in alcoholic solutions of the 

 vegeto-alkalies, when dry, are decomposed, with explosion, by tem- 

 peratures of 240 to 248 F. ; even when heated upon paper, upon 

 using a tube, the detonation is of considerable force. The results are 

 easily understood ; the effect forms a character of the compounds t- 



6. ON THE ACTION OP BROMIC AND CHLORIC ACIDS ON ALCOHOL. 



(Serullas.) 



In consequence of some suspicions relative to a process for the pre- 

 paration of bromic acid, in which alcohol was used, M. Serullas 

 mixed about equal quantities of solution of that acid and strong 

 alcohol ; the liquids immediately became coloured, much heat was 

 evolved, the fluids boiled, and very powerful vapours of acetic ether 



* Aim. de Chiinie, xlv. 68. f Ibid. 



2 S2 



