MISCELLANY. 
177 
a wine yellow, and next a beautiful red colour, from a portion of the acid 
undergoing decomposition, while the iodine disengaged is dissolved in the 
rest of the acid. It has been ascertained that this process of decomposi- 
tion may go on till one-half of the acid is decomposed, when the colour 
of the liquid is a very dark red, approaching to black. The diluted acid, 
however, prepared as above, may be kept many months without at all 
approaching this limit. — London Med. Gaz. and Jlmer. Jour, of Med. Set. 
Iodide of Starch. — Dr. Andrew Buchanan, Junior Surgeon to the Glas- 
gow Royal Infirmary, in a communication in the London Medical Gazette 
(July 2, 1836,) extols this preparation of iodine, which he prepares in the 
following manner: — R. Iodine gr. xxiv.; Amyli inpulverem tenuissimum 
triti ^j. The iodine is first triturated into a little water, and the starch 
gradually added, the trituration being continued till the compound as- 
sumes a uniform blue colour. The iodide is then dried with a heat so 
gentle as not to drive off the iodine, and it must be afterwards kept in a 
well stopped bottle. Ibid. 
Iodine in Minerals and Plants. — Arago stated to the academy that Del 
Rio had discovered iodine in the horn silver of Albarradon (a district sit- 
uated in the department Zocateras, Mexico;) that iodine had also been met 
with in the white lead of the mine of Catorce by M. Bustaments. Lastly, 
that iodine, which was only supposed to exist in sea plants, has been 
found in the sabila and romeritos. The first is a plant of the genus agava, 
which grows in the plains and sides of mountains ; the latter a sort of 
barilla which grows in the floating gardens of the fresh water lakes in the 
neighbourhood of the town of Mexico. Journ. dePharm. 
Crystallized Hydrate of Potash. — The crystallization of hydrate of pot- 
ash from cold solutions is understood, but the separation of the soft hy- 
drate from caustic potash, melted at a red heat, has been less attended to. 
Walter digested from 3 to 4 lbs. of melted potash with a little water, 
allowed the effect of the heat to pass away, added as much water as was 
sufficient to dissolve the whole, allowed it to stand for 12 hours, and then 
decanted the solution. The bottom of the vessel was covered with many 
clear crystals. To preserve these, they must be dropped through a glass 
funnel into a vessel with a ground stopper, and placed in a cool place. 
They appear to be acute rhomboids with truncated angles. In vacuo over 
sulphuric acid they effloresce and become dull. They dissolve in water, 
producing cold. In the concentrated mineral acid they dissolve with the 
evolution of heat. In spirit they dissolve without giving out heat. They 
dissolve in caustic ammonia. By this means bubbles of ammoniacal gas 
are discharged from the crystals, but which are condensed before they 
reach the surface of the liquid. The composition was determined by 
dissolving a portion of the crystals in muriatic acid, evaporating the solu- 
