236 Intelligence and Miscellaneous Articles. 



INSOLUBLE SALTS OF THE ALKALINE EARTHS DISSOLVED BY 

 HYDROCHLORATE OF AMMONIA AND CHLORIDE OF SODIUM. 



M. H. Wackenroder states that sulphate of barytes is quite inso- 

 luble, but that the sulphates of lime and strontia are soluble in so- 

 lution of chloride of sodium ; the latter, though fslowly, yet com- 

 pletely, and it is entirely precipitable from solution by dilute 

 sulphuric acid. Sulphate of lime dissolves very readily in solution 

 of chloride of sodium, and cannot be precipitated by dilute sulphuric 

 acid. — Ibid. 



PRODUCTION OF FORMIC ACID IN OIL OF TURPENTINE. 



The acid reaction of the oil of turpentine of commerce is derived 

 from formic acid, the presence of which is readily detected in the 

 water employed in its rectification. 



According to M. Weppen, the formation of this acid can be ex- 

 plained only by the oxidation of the oil by contact with the air. 

 The action may be very simple : 



1 atom of oil of turpentine .... =5C8H + 10O = 



2 formic acid =4C4H+ 60 



1 .... carbonic acid = 1 C 20 



2 water = 4 H + 20 



It appeared to M. Weppen a subject of interest to inquire if these 

 changes really occurred, or whether other products were not also 

 formed during oxidation. 



As oil of turpentine oxidizes slowly by exposure to the air, he 

 endeavoured to effect it by distillation with chromate of lead and dilute, 

 sulphuric acid. Soon after ebullition had commenced, the chromate 

 of lead was reduced, and acidulous water distilled with the oil of 

 turpentine, in which the presence of formic acid was discoverable ; 

 there was evolved, at the same time, carbonic acid sufficient to ren- 

 der lime-water very turbid. A question however arises, whether 

 this carbonic acid is really derived from the oxidation of the oil of 

 turpentine, or is a secondary product of the formic acid. — Ibid. 



PRECIPITATION OF CERTAIN SALTS BY EXCESS OF ACIDS. 

 BY M. WACKENRODER. 



It is an important circumstance in analysis, that certain salts, 

 especially sulphates and oxalates, are precipitated by an excess of 

 acid, if they are dissolved in other acids, and especially in nitric or 

 hydrochloric acid. If, for example, protosulphate of mercury be 

 dissolved in diluted nitric acid, this salt may be almost perfectly 

 separated by the addition of dilute sulphuric acid. Nitric acid, 

 though with difficulty, dissolves sulphate of lead completely ; but if 

 dilute sulphuric acid be added to the solution, the sulphate of lead is 

 precipitated. 



If a great excess of nitric acid or hydrochloric acid holding lead 

 in solution have not the excess got rid of either by saturation or 



