203 On Iodine. [March, 



engaged, and the same products are obtained as when iodine is 

 dissolved in that alkali. The hydiiodatc of ammonia, which has 

 the property of dissolving a great deal of iodine, gradually decom- 

 poses the fulminating pov;der, while azote is set at liberty. Water 

 itself has this property, though in a much weaker degree, as M. 

 Courtois observed long ago. Thus the elements of ioduret of azote 

 are but very little condensed. It ought to be prepared with great 

 precautions, and should not be preserved. 



'. It would be difficult to determine by direct experiment the pro- 

 portion of the principles of this compound ; but we ascertain them 

 correctly in the following manner : — 



We have seen that the ratio of hydrogen to iodine is l'32(iS to 

 156 '21 J and as ammonia is composed of 



Hydrogen 1 8-475(; 



Azote Sl-5244 



it follows that the ratio of azote to iodine is that of 5*8544 to 

 156-21 ; and such is the ratio of the elements of the fulminating 

 compound. If we reduce these elements to volumes by dividing 

 5-8544 by 0-96913, the density of azote, and 156-21 by 8-6195, 

 the density of the vapour of iodine, we find that the proportion in 

 volume of the elements is one azote and three iodine. We obtain 

 this proportion directly by observing that the vapour of iodine and 

 hydrogen combine in equal volumes j and that in ammonia tiie 

 volume of hydrogen is to that of azote as three to one. 



If we decompose a gramme (15*444 grains) of the fulminating 

 powder, we obtain, at the temperature of S2°, and under the 

 pressure of 30 inches of mercury, a gaseous mixture amounting to 

 0*1152 litre (7-03 cubic inches, nnd composed of 0-0864 of the 

 vapour of iodine and 0-0288 of azote. Though this volume be 

 inconsiderable, yet the explosion is very loud, because it is instant- 

 aneous. The same difficulty occurs here as in the detonation of the 

 chloruret of azote, and of all the fulminating bodies which are 

 decomposed into simple substances, producing at the same time 

 heat and light. I do not pretend to resolve this difficulty ; but is it 

 not possible that the heat and light which make their appearance in 

 these cases is produced by the shock of the gas produced against the 

 air, or any other fluid, as happens when air is compressed or intro- 

 duced into a vacuum ? * Is it in fact necessary to have recourse to 

 heat to communicate elasticity to gaseous substances condensed in a 

 compound, or, which is the same thing, to pui their elements in a 

 state of repulsion ? Do we not see, on tiie contrarj', a weak 

 electricity destroy the combinations which resist the repulsive force 



* To explain my idea the better, let us conceive a volume of air in the middle 

 of which ii a small metallic ball, cnntaining any elastic fluid in a great degree of 

 compression, and at the same temperature with the surrounding fluid. If we 

 suppose the ball suddenly to burst, which will represent a detoiialiorf, we shall 

 have heat and lig-ht produced. Now in the Jptonalioii of ioduret or chloruret of 

 azote the dcvcli _/t;:icnt of the gas decs not appear to ine to differ from that of air 

 Strongly conipresstu in our ball. 



G 



