Chemical Science. — 381 
mass of minute globules of mercury attached to the glass, those in the 
centre being largest. Hence arises the question, whether this vapour 
may not have some influence on the oscillations of the barometer ?— 
Bib. Univ. xxv. 93. 
_ 15. Combustion of Iron by Sulphur.—Dr. Hare makes this experi- 
ment in the following manner :—A gun-barrel is heated red at the 
butt end, and a piece of sulphur thrown into it ; then either blowing 
through the barrel, or closing the mouth with a cork, will produce a 
jet of sulphurous vapour at the touch-hole, to which if iron wire 
be exposed it will burn as if ignited in oxygen gas, and fall in fused 
globules of proto-sulphuret of iron. 
16. Ammonia in Oxides of Iron.—M. Chevalier has stated to the 
Royal Academy, that he has ascertained the presence of ammonia 
in various oxides of iron, and promises further accounts.—Ann. de 
Chim. xxv. 429. 
17. Iodous Acid.—Il Sig. Sementini, of Naples, has published an 
account of a combination of iodine and oxygen, containing less of the 
latter principle than iodic acid. Itis obtained in the following man- 
ner :—equal parts of chlorate of potassa and iodine are to be triturated 
together, in a glass or porcelane mortar, until they form a very fine 
pulverulent yellow mass, in which the metallic aspect of the iodine 
has entirely disappeared. If there be excess of iodine the mixture 
will have a lead colour. ‘This mixture is to be put into a retort 
the neck being preserved clean, and a receiver is to be attached with 
a tube passing to the pneumatic trough. Heat is then to be applied, 
and for this purpose a spirit lamp will be found sufficient; at first a 
few violet vapours rise, but as soon as the chlorate begins to lose 
oxygen dense yellow fumes will appear, which will be condensed in 
the neck of the retort into a yellow liquid, and run in drops into the 
receiver ; oxygen gas will at the same time come over. When the va- 
pour ceases to rise, the process is finished, and the iodous acid ob- 
tained will have the following properties :— 
Its colour is yellow ; its taste acid and astringent, and leaving a burn- 
ing sensation on the tongue. It is of an oily consistency, and flows 
with difficulty. It is heavier than water, sinking in it. It has a par- 
ticular odour, disagreeable, and something resembling that of eu- 
chlorine. It permanently reddens vegetable blues, but does not de- 
stroy them as chloric acid does. It is very soluble in water and al- 
cohol, producing amber-coloured solutions. It evaporates slowly, 
and entirely in the air. At 112° F. it volatilizes rapidly, forming 
the dense vapour before mentioned. It is decomposed by sulphur, 
disengaging a little heat, and liberating violet vapours. Carbon has 
no action on itat any temperature. Solution of sulphurous acid de- 
composes it as well as iodic acid, i the iodine as a brown 
2 
VoL, XVII. 
