318 Intelligence and Miscellaneous Articles. 



was mixed with the sulphuret of arsenic. I could never detect a 

 trace of lead, which circumstance will be accounted for in a subse- 

 quent notice. 



Having always found sulphate of tin in the sulphuric acids sub- 

 mitted to examination, I questioned myself as to its origin, and I 

 soon ascertained that it was simply due to the action which the 

 acid has on the solder of the leaden chambers. Now it is well 

 known that the soldered portions are very rapidly corroded by the 

 acid vapour with which they are in constant contact. 



The presence of tin in the sulphuric acid of commerce accounts 

 for the traces of this metal which have sometimes been found in the 

 green vitriol of commerce. — Jourti. de Pharm. for August. 



ON THE OXIDIZING ACTION OF CHLORATE OF POTASH ON 

 NEUTRAL SUBSTANCES. 



M. Barreswill has communicated to the ' Journal de Pharmacie ' 

 for August a very interesting fact which he had occasion to observe 

 in conjunction with M. Kochlin, while investigating the mode of 

 action of the chlorate of potash as an oxidizing agent. 



When a hot solution of this salt is mixed with a solution of the 

 protosulphate of iron, likewise hot, the two perfectly-transparent 

 liquids immediately become turbid, and exhibit in suspension a con- 

 siderable red precipitate. The filtered liquor is also of a red colour. 

 The reaction is one of the most simple and most precise that can be 

 imagined; the chlorate of potash loses the whole of its oxygen, 

 which goes entirely to the protosulphate of iron, causing this to pass 

 into the state of the persulphate, in part neutral salt and in part 

 basic, without any perchlorate being formed : — 



KO CIO 5 + 12FeO, SO 3 = KC1 + 3Fe 2 O 3 , (SO 3 ) 3 (in solution) 

 + 3Fe 2 O 3 SO 3 (precipitated). 



The same reaction takes place in the cold, but more slowly. At the 

 boiling temperature it is complicated, from the action of the neutral 

 sulphate of the peroxide of iron on the chlorate of potash, which 

 may be compared to that of sulphuric acid ; for, in fact, the neutral 

 sulphate is converted into the subsulphate, and the two equivalents 

 of acid react on the chlorate of potash. The subsulphate deposited 

 from a hot solution is yellow, anhydrous, and dissolves with diffi- 

 culty in acids, while the subsalt which subsides from a cold solution 

 is red, hydrated, and is very soluble in dilute acids. All the neutral 

 salts of the protoxide of iron behave in a similar manner, which 

 indeed is the case with all neutral -substances susceptible of oxida- 

 tion by exposure to the atmosphere ; the chlorate of potash aban- 

 dons the whole of its oxygen to them. 



Iron and zinc become oxidized in a solution of the chlorate, and 

 soon the liquid contains chloride only ; the action, which is some- 

 what energetic, is singularly diminished by the layer of oxide which 

 forms and protects the metal. 



Lead does not oxidize under the same circumstances, but if placed 



