270 M. Vaiiquelin on the Existence of Iodine in Minerals. 



grammes. It was inflamed by heat, giving out a smell of sul- 

 phurous acid, and leaving as a residue sulphuret of lead 

 mixed with a little iron, which weighed 1'58 gramme. 



The first substance, weighing 6j^% grammes, treated with 

 muriatic acid aided by heat, gave the latter a reddish-brown 

 colour, and produced a slight effervescence, with the smell of 

 chlorine. As the heat increased, this effervescence also in- 

 creased, and a fine violet-colour was soon developed ; when, 

 in order to preserve this violet matter, the vessel was imme- 

 diately withdrawn from the fire. 



At the bottom of the acid remained a yellow substance con- 

 taining gray particles, which were dissolved in the hot water 

 with which the substance was washed. 



This water had acquired a reddish-brown tinge, and the 

 property of imparting to a solution of starch a fine blue 

 colour. 



Suspecting, although the circumstance appeared so extra- 

 ordinary, that this violet vapour was produced by iodine, the 

 above muriatic solution, after having been a little diluted with 

 water, was submitted to distillation. It was with pleasure we 

 saw our supj)osition realized : for soon the violet vapours, on 

 rising, crystallized against the sides of the adopter and balloon 

 adapted to the retort, assuming the acicular form and the co- 

 lour peculiar to iodine ; but the acid was not entirely de- 

 colorized. Although the yellow substance had been boiling 

 for some time with the muriatic acid, it was not entirely decom- 

 posed ; for having melted 2-38 grammes of it with potash, and 

 washed the produce with water, we obtained an alkaline so- 

 lution, which, saturated with sulphuric acid and mixed with 

 starch-water, produced, with the addition of some drops of 

 solution of chlorine, a very fine blue colour. The substance 

 which did not dissolve in the water was metallic silver in 

 the state of powder, weighing 1*63 gramme. 



Assured therefore, by the preceding experiments, of the pre- 

 sence of iodine in the argentiferous mineral, we endea- 

 voured to obtain it by a more direct process, which would 

 permit us to determine its quality and to ascertain the mode 

 of combination in which it occurs. 



We accordingly heated 5 grammes of it in powder with 2 

 grammes of caustic potash and a little water to iacililate their 

 mixture. The substance having been heated for some time, we 

 washed it out in water; and after having decanted the latter, 

 washed the residuum till all the alkaline matter was removed. 

 This residuum was of a dirty-yellow, and weighed 4*46 

 grammes. — We shall return to its examination presently. 



A portion of the alkaline solution saturated with nitric acid 



took 



