Intelligence and Miscellaneous Articles. 235 



nerally consists of a mixture of variable quantities of protiodide, per- 

 iodide and sesquioxide of iron and free iodine. 



M. Mialhe states that the solid protiodide is easily prepared, even 

 in contact with the air, by the following process : — prepare, in the 

 usual manner, a solution of protiodide of iron, and evaporate it in a 

 porcelain capsule, containing iron turnings or wire, quite free from 

 oxide ; the evaporation must be carefully conducted, and continued 

 until a small quantity of the salt being taken up by a glass rod and 

 deposited on a cool substance, it instantly solidifies. When this state 

 of concentration is effected, the protiodide of iron is to be carefully 

 poured off from the iron in the capsule, on a plate of glass or porce- 

 lain, and immediately afterwards introduced into small well-stopped 

 dry bottles. 



The properties of the protiodide of iron thus prepared are, that it 

 is in the form of brittle scales of different degrees of thickness, which 

 when broken exhibit evident traces of crystallization ; it is extremely 

 deliquescent ; its solution is greenish ; it is precipitated white by 

 ammonia, and bluish- white by ferrocyanide of potassium ; when 

 triturated with starch no blue colour is produced. — Journ. dePharm. 

 etde Chim., Janvier 1844. 



ON CHLORAZOTIC ACID. BY M. BAUDRIMONT. 



M. Baudrimont remarks, that although aqua-regia has been known 

 for some centuries, and that frequent use is made of it, it has been 

 subjected to but few researches. It is generally supposed that it 

 owes its property of dissolving gold to the presence of free chlorine ; 

 in 1831, however, Mr. Edmund Davy published a memoir, which tends 

 to prove that the active product of aqua-regia is a peculiar gas formed 

 of equal volumes of chlorine and nitric oxide gases, uncondensed ; he 

 states the specific gravity of this gas to be 1*759, and he has 

 given it the name of chloronitrous gas. The process by which Mr. 

 E. Davy obtained this gas was by acting upon fused chloride of po- 

 tassium or sodium by concentrated nitric acid. The nature of the 

 substances reacting on each other, clearly prove that it is impossible 

 to obtain this gas unmixed with chlorine, as shown by the following 

 equation : — 



4Az0 6 H + 3ClNa = 3Az0 6 Na 4- Az O 2 , CI 9 + CI. 



The presence of chlorine in the supposed gas from aqua-regia 

 preventing a proper examination of its qualities, the following were 

 the results of the experiments made on this subject by M. Baudri- 

 mont : — 



When a mixture of two parts by weight of nitric and three of hy- 

 drochloric acid of commerce is made, a red gas begins to extricate at 

 about 1SG° F. If this gas be passed into a U-shaped tube, placed in 

 powdered ice, the condensable portions of it are separated. Expe- 

 riment showed that the first portions of the gas are mixed with hy- 

 drochloric acid, and that the latter only are sufficiently pure ; this 

 gas does not redden dry litmus paper, but decolorizes it after some 

 hours ; when it is moist the paper is reddened by it ; at 32° F. water 

 dissolves - 3928 of its weight, or 121 times its volume ; the solution 



