174 Foreign and Miscellaneous Intelligence. 



hot water dissolves about 5.3 per cent and deposits nearly one half 

 on cooling-. It requires a much higher heat than white arsenic for 

 its volatilisation (550 Fahrenheit), and at 600 is decomposed, 

 giving off first arsenical fumes arid then evolving iodine. On ana- 

 lysing the substance it turned out to be a compound of 

 Arsenious acid . . 63 . 3 



Iodide of potassium . 36.7 



100.0 



Notwithstanding the novelty of such a compound, in which it is 

 impossible to tell whether the white arsenic acts the part of acid or 

 base, although it is present nearly to the extent of five atoms, and 

 where no analogy to the composition of a double salt appears obvious ; 

 yet Professor Emmett observes there are facts from which its exist- 

 ence must be inferred. Thus iodide of potassium, even when added 

 in great excess, does not precipitate the whole of the arsenite of 

 potassa, nor is it capable of diminishing the alkaline reaction ; on 

 the contrary, when arsenite of potassa is so far neutralized by free 

 acetic or arsenious acid as not to affect turmeric paper, it acquires 

 this property by the addition of iodide of potassium, apparently in 

 consequence of a union between the latter substance and the excess 

 of arsenious acid, which while dissolved had the power of counteract- 

 ing the alkaline effect : other considerations lead to the same result. 

 If subsequent experiments should establish the existence of such 

 a compound, it will be a solitary but striking example of what may 

 be considered a chemical hybrid *. 



9. AMMONIA IN NATIVE OXIDE OF IRON. (Boussingault.) 



Vauquelin shewed that rust of iron contained ammonia, and Che- 

 vallier shewed that the natural oxide of iron also contained the 

 same alkali. As the oxides the latter worked with came from a dis- 

 tance, it might be urged that they had acquired ammonia by the 

 way ; for if rust formed within houses absorbed ammonia, so also 

 might native oxides acquire that alkali in its transit from place to 

 place. M. Boussingault, therefore, sought to ascertain whether the 

 natural oxides of iron gave the substance immediately after their 

 extraction from the earth. 



In the mine of Cumba near Marmato, a large vein of hydrated 

 oxide of iron in syenitic porphyry is worked as a gold ore. In a 

 part of this mine, called por a fuera, where the work proceeds with 

 activity, about a foot of mineral was broken down at the end of the 

 excavation so as to expose a fresh surface, and then a hole was 

 bored in the very middle of the vein ; after having been carried 

 eight inches deep, the powder of the ore was collected carefully in a 

 basin, placed under the hole, and touched by nothing but the tool. 

 Four ounces of this ore were then bruised and rubbed in distilled 



* Sillimau's Journal, xviii., 58, 



