CHEMICAL SCIENCE. 231 



NEW METHOD OF PREPARING POWDERS TO BE USED IN MEDICINE. 



TINCTURES, as is well known, generally possess the most active prop- 

 erties of the drugs from which they are prepared, but the amount of 

 spirit they contain often renders their employment objectionable. 

 "Wittke, of Erfurt, therefore, mixes tincture of hellebore, cinchona, 

 &c., with an equal quantity of sugar, evaporates to dryness, and pow- 

 ders the residuum. In this manner, he succeeds in concentrating, in a 

 very small bulk, the active portion of a very large quantity of the drug, 

 and he prescribes the powder as saccharized cinchona, &c. These 

 preparations bear some analogy to conserves, over which, however, 

 they have a great advantage in being free from mucilage, vegetable 

 albumen, and other inert matters. 



IODINE IN THE ATMOSPHERE. 



M. CHATIX, of France, in the continuation of his experiments on 

 iodine, publishes the following observations on its presence in the 

 atmosphere. The constant dispersion of iodine, through the slow, spon- 

 taneous evaporation of the waters which contain it, and its more rapid 

 volatilization when heat is applied to these ; its elimination from hard 

 waters, which is so speedy that it can seldom be detected therein, even 

 when they spring from highly iodined soils ; and the results, though 

 incomplete, which have been obtained by operating on rain-water, are 

 so many circumstances which have led M. Chatin to conclude that this 

 substance must exist in the atmosphere. He estimates the 4000 hires 

 of air which traverse the lungs of a man in twelve hours, as containing 

 one forty-fifth milligramme, i. e., the same quantity that is found in a 

 litre of potable water, moderately iodined. This iodine becomes fixed 

 during the act of respiration ; the expired gases exhibiting about one 

 fifth of the iodine contained in the inspired air. The atmosphere of 

 ill- ventilated and crowded places is, in part, deprived of its iodine. 

 The proportion of iodine contained in the waters of a given locality 

 indicates approximatively the quantity contained in its atmosphere. 

 Rain is notably more iodined in the interior than in the vicinity of the 

 coast, inasmuch as the iodine of fresh waters is much more completely 

 dispersed than is that of sea-water. Great differences, due to causes 

 not yet appreciated, exist in the amount of iodine contained in the rain 

 of the same locality ; the proportion, however, always diminishing 

 when the rains are very prolonged. As rain always loses its iodine on 

 falling, this might be fixed for useful purposes by placing in cisterns a 

 millionth or half-millionth part of carbonate of potash. Snow is 

 iodined ; but, cateris paribus, less so than rain. Dew contains iodine. 

 Additional observations are required to decide whether iodine exists in 

 the air in the free state, as hydriodic acid, as hydriodate of ammonia, 

 or as forming a volatile combination with certain organic elements. 

 Gaz. Med., 1851, No. 19, p. 300. 



NEW METHOD OP OBTAINING OXYGEN FROM ATMOSPHERIC AIR. 



LAVOISIER resolved atmospheric air into its constituents by keeping 

 a confined portion, for twelve days, in contact with mercury, heated to 



