SCIENTIFIC SUMMARY. 527 
porcelain tube filled with pieces of charcoal and heated to redness. — 
Zeitschrift fur Chemie , etc., vii., p. 220. 
A new Acid isomeric with sulpho-vinic Acid was obtained by Mr. 
Northcote, by adding sulphuric acid to an alcoholic solution of potash 
which had been kept for some years. Heat is not required for its produc- 
tion, thus proving its distinctness from the sulpho-vinic compound. — Vide 
The Chemical News , 227. 
Decomposition of Water by Phosphorus, Arsenic, and Antimony, and Evolu- 
tion of Ammonia. — The solution of phosphorus in nitric acid, concentrated 
or diluted with one or two volumes of water, is, as is well known, effected 
with disengagement of nitrous vapour, abundant if the acid is concentrated, 
and diminishing in proportion as it is more diluted. In any case if, 
when the solution is effected, excess of potash is added to the hot solution, 
sufficient ammonia is disengaged to become evident, both by its odour 
and by reagents. Whether normal or amorphous phosphorus is used 
in this operation, the phenomena and the products are identical. It was, 
then, interesting to ascertain whether the fact of the production of 
ammonia was observable with the bodies forming part of the phosphorus 
group, as arsenic and antimony. In order to determine this, M. Personne 
operated with arsenic and with antimony purified three times by fusion 
with nitre. These two bodies, pulverised and heated, were attacked by 
nitric acid, diluted with its volume of water. Under these circumstances, 
arsenic is easily attacked, giving arsenious and a little arsenic acid. 
Antimony, on the contrary, is attacked with more difficulty. However that 
may be, if ammonia is looked for in the liquids obtained, it will be found 
that these two bodies have behaved like phosphorus, with this difference, 
that phosphorus gives more ammonia than arsenic, and arsenic more than 
antimony. The phenomenon of the formation of ammonia by the decom- 
position of water under the influence of nitric acid has hitherto been 
observed only with metals of the third and fourth sections, as iron, tin, 
zinc, &c. We now see that this phenomenon is not limited to these 
metals, but belongs equally to the metalloids of the phosphorus group. 
The Preparation of Iodide of Ammonium . — This haloid salt is thus pre- 
pared by Dr. Jacobsen : he dissolves equivalent weights of pure iodide of 
potassium and pure sulphate of ammonia in the smallest possible quantity 
of boiling distilled water. One part of sulphate of ammonia will require 
about one and one-third of its weight, and iodide of potassium about half 
its weight of boiling water for solution. The two solutions are then mixed 
and well stirred. After the mixture has cooled, water containing fifteen 
per cent, of alcohol is added, and the whole is allowed to stand for twelve 
hours. In very cold weather less alcohol will suffice to separate the 
sulphate of potash formed. According to Schiff, 100 parts of water and 
10 of alcohol, at 15° centigrade, only dissolve 8*9 parts of sulphate of 
potash. The iodide of ammonium, in consequence of its greater solubility, 
remains in the solution, which is now withdrawn from the precipitated 
sulphate of potash, filtered and evaporated until a pellicle forms. As the 
solution is very concentrated, the evaporation is quickly effected. After 
the crystals of iodide of ammonium are formed, they are drained from the 
mother-liquor, which, together with the residue of sulphate of potash, is 
