Miscellanies. 155 



13tlj. Again, vegelables, under certain circumstances, decompose 

 carbonic acid, and restore oxygen to the atmosphere, but this is de- 

 pendent not upon the respiratory but the digestive system ; it arises 

 in part from the decomposition of water, but chiefly from tiie de- 

 composition of carbonic acid, absorbed either in the form of gas, or 

 in combination with water either by the roots, or leaves, or both. Its 

 analogy to animal digestion is obvious, for to both plants and animals, 

 carbonic acid, though deleterious when breathed, is invigorating to the 

 digestive system when absorbed as food. — Idem. 



8. Ammonia in native oxide of iron. — (Ann. de Chlmie, t. xliii, 

 p. 334.) — 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 afuei'a, 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 being 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 water, the fil- 

 tered liquor was acidified by muriatic acid and evaporated ; it left 

 fifteen grains of residue, which being introduced into a glass tube 

 with a piece of quick lime slightly moistened, and heated, gave am- 

 monia, sensible not only to test papers, but also by its strong odor. 

 Hence it results, as M. Chevalier has stated, that the natural oxides 

 of iron contain ammonia, and this fact, conjoined with that of Austin, 

 that ammonia is formed by the oxidation of iron in contact with air and 

 water, acquires a certain degree of geological importance. — Idem. 



9. Salicine. — (Leroux, Ann. de Chim.) — This substance is in the 

 form of very fine nacreous white crystals, very soluble in water and 

 alcohol, but not in ether ; it is very bitter and partakes of the odor 

 of willow bark. In order to obtain it, three pounds of the bark of 

 the willow, (Salix Helix,) dried and pulverized, are to be boiled in 

 fifteen pounds of water, with four ounces of carbonate of potash, for 

 an hour ; it is to be filtered, and when cold, two pounds of solution 

 of sub-acetate of lead added : when settled, it is to be filtered, treated 

 with sulphuric acid, the rest of the lead precipitated by sulphuretted 

 hydrogen, the excess of acid neutralized by carbonate of lime, again 

 filtered, the liquid concentrated and saturated by dilute sulphuric acid, 



