Foreign Literature and Science. 387 



mine. The latter crystallizes and may be distilled. It be- 

 comes gaseous at 1 5°, has a pungent odour, is soluble in wa- 

 ter and alcohol, and is excessively deleterious. — Ibid. 



26. Formation of Ammonia. — Note by M. Chevalier. — 

 Two ounces of clean turnings of iron were heated in a cov- 

 ered crucible, and when cool, were introduced with an ounce 

 of water into a flask, the beak of which dipped into mercu- 

 ry. After an exposure of ten hours, it gave signs of alca- 

 linity ; and four days afterwards, the water saturated by 

 muriatic acid, produced a very sensible quantity of muriate 

 of ammonia. The natural oxides of iron all contain it ; and 

 one hundred and fifty grammes of red hematite pulverised, 

 furnished two grammes of hydro -chlorate of ammonia. The 

 ferruginous waters of Passy- also contain ammonia. These 

 facts ought to be added to those already known with regard 

 to the formation of ammonia by the azote of the air. — Ibid. 



27. Fluoric Acid and Fluates. — Chemists are divided in 

 opinion on the nature of fluoric acid. Some, with Berzelius, 

 consider it as a compound of fluor and oxygen, — others, of 

 fluor and hydrogen. If fluor spar is a compound of lime 

 (calcium and oxygen,) and fluoric acid (fluor and oxygen,) 

 in attacking it with concentrated sulphuric acid, there is a 

 formation of sulphate of lime, a disengagement of fluoric 

 acid (fluoric and oxygen,) and a disengagement of the wa- 

 ter previously combined with the sulphuric acid. If fluor 

 spar is simply a fluoride of calcium, on attacking it with 

 concentrated sulphuric acid, one portion of the water of 

 the acid will be decomposed ; its oxygen will unite with the 

 calcium, and produce lime, which will form sulphate of lime, 

 and the hydrogen, uniting with the fluor, will produce a hy- 

 dracid, which escapes in the gaseous form. The question 

 has remained hitherto undetermined, from the difficulty of 

 getting clear of the action of the water. But, M. Kuhlmann 

 having thought of treating fluor spar with anhydrous sulphu- 

 ric acid, found that the acid was not decomposed ; a proof 

 that fluor spar is a true fluoride of calcium, and fluoric acid 

 a real hydracid.— Ibid. 



28. Emigration of Butterflies. — A singular phenomenon 

 was observed, in June last, by a respectable family of Neuf- 

 chatel, (Switzerland,) while at their country seat in the dis- 



