72 Intelligence and Miscellaneous Articles. 



ARTIFICIAL SULPHURET OF ZINC. 

 M. Berthier prepares this sulphuret as follows: — Dissolve zinc 

 foil in sulphuric acid, and separate the small quantity of charcoal 

 and lead which remains undissolved ; evaporate the solution to 

 dryness, and add a few drops of nitric acid to peroxidize the iron ; 

 calcine slightly to decompose apart of the sulphates, and redissolve 

 in water. If the solution still contains iron, which may be determined 

 by a prussiate, repeat the operation ; when there is no iron remain- 

 ing, add a few drops of hydrosulphuret of ammonia to separate any 

 trace of lead which may be dissolved. By slowly heating the sul- 

 phuret in an earthenware crucible to whiteness, either alone or mixed 

 with 15 per cent of charcoal, it is reduced to a sulphuret ; but as it 

 almost always happens that a portion of the sulphate is decomposed 

 by the heat before charcoal can reduce it, the sulphuret is mixed 

 with a little oxide; this may be separated by pure dilute muriatic 

 acid, which readily dissolves the oxide, and acts but feebly upon 

 the sulphuret ; it is then to be washed and dried. The pure sulphuret 

 of zinc is pulverulent, and as white as the oxide. — Ann. de Chim. 



PROTOFERROCYANATE OF IRON. 

 It is not I believe generally known, that a solution of protoxide 

 of iron without any admixture of peroxide, may be obtained by 

 putting the metal into an aqueous solution of sulphurous acid, and 

 suffering the mixture to remain for a short time without the contact 

 of atmospheric air. When a solution of ferrocyanate of potash is 

 added, a perfectly white precipitate is formed, which is the proto- 

 ferrocyanate of iron. The action of sulphurous acid upon iron is 

 also remarkable on another account, viz. that no gas is evolved 

 during the solution of the metal, if made to take place in closely 

 stopped bottles. It appears that a part of the sulphurous acid is 

 decomposed by the nascent hydrogen of the water, and the sulphu- 

 retted hydrogen which results remains in solution. — R. P. 



CYANIC ACID. 



M. Liebig states that cyanic acid may be obtained in a separate 

 state, by passing a current of sulphuretted hydrogen gas through 

 water in which cyanate of silver is suspended. This acid reddens 

 litmus strongly, its taste is acid ; it possesses the smell which is 

 always perceived when any of its salts are decomposed by an acid : 

 it neutralizes bases perfectly, but when in contact with water it suf- 

 fers decomnosition in a few hours, and is converted into carbonic acid 

 gas and ammonia. The sulphuretted hydrogen must not be passed 

 so as to decompose all the cyanate of silver; for then the cyanic acid 

 is converted into other products by the excess of sulphuretted hy- 

 drogen. — Ann. de Chim. Oct. 1826. 



SEPARATION OF IRON FROM MANGANESE. 



M. Quesneville, jun. proposes the following process for separating 

 these metals : — Dissolve both oxides in muriatic acid and boil the so- 

 lution for some time to expel all excess of acid, in order to render the 

 solution as neutral as possible. Dilute the solution with a large 



quantity 



