372 ANNUAL OF SCIENTIFIC DISCOVERT. 



in hot countries, it is an invaluable preventive of the formation of mag- 

 gots in wounds, and the more so inasmuch as its use is attended with no dis- 

 advantages, unless employed in large quantities in closed bedrooms, when it 

 may give rise to confusion in the head, such as is produced by flowers or 

 new hay. It has been long used as a means of preserving insects; and can- 

 not be too strongl}' recommended to those who have the care of herbarian 

 and other natural-history collections, liable to the depredations of insects. 

 Unfortunately, the demand for the powder has been so great of late, as to 

 lead to its adulteration, by the addition of the stalks and leaves of the 

 plants to the flowers, and to the mixing of the new with stale powder. As a 

 general rule, the powder purchasable in Germany is very different from the 

 Asiatic in color, smell, and efficiency. Buchner's Report. 



ON THE ACTION OF GROWING VEGETATION IN NEUTRALIZING 



MIASMA. 



Lieutenant Maury, of the National Observatory, in an article communi- 

 cated to the Rural New-Yorker, maintains that the growing of sunflowers 

 around a dwelling located near a fever-and-ague region, neutralizes the mi- 

 asma, in which that disease originates; and seems to support the theory by 

 successful experiment. He was led to make the experiment by the follow- 

 ing circumstances. The dwelling of the superintendent of the observatory 

 at Washington, is situated on a hill on the left bank of the Potomac, in lat. 

 38 39' 53". It is ninety-four feet above low-water mark, and about four 

 hundred yards from the river. The grounds pertaining to it, about seven- 

 teen acres, are enclosed by a wall on the east, south, and west, and with a 

 picket fence on the north. The south and west walls run parallel with the 

 river, the Chesapeake and Ohio Canal, and a row of sycamores, of some 

 twenty years' growth, separating fhe Avail from the river. In fact, the river, 

 with its marshes, encircles about half of the grounds. The house is, there- 

 fore, in the bend of the river; and the place is so unhealthy, that the family 

 of the superintendent are compelled to vacate it five months out of the 

 twelve, the marshes being covered with a rank growth of grass and weeds, 

 which begin to decay early in August. A knowledge of these facts led Lieut. 

 Maury to the following process of reasoning: 



If it be the decay of the vegetable matter on the marshes that produces 

 the sickness on the hill, then the sickness must be owing to the deleterious 

 effects of some gas, miasm, or effluvium, that is set free during decomposi- 

 tion; and if so, the poisonous matter, or the basis of it, whatever it be, must 

 have been elaborated during the growth of the weeds, and set free in their 

 decay. Now, if this reasoning be good, why might AVC not, by planting 

 other A'cgetable matter betAveen us and the marshes, and by bringing it into 

 vigorous growth just about the time that that of the marshes begins to decay, 

 bring fresh forces of the vegetable kingdom again to play upon this poison- 

 ous matter, and elaborate it again into vegetable tissue, and so purify the 

 air? 



This reasoning appeared plausible enough to justify the trouble and 

 expense of experiment; and I AA-as encouraged to expect more or less success 

 from it, in the circumstance that everybody said, " Plant trees betAveen you 

 and the marshes they Avill keep off the chills." But as to the trees, it so 

 happens that at the very time Avhen the decomposition on the marshes is 

 going on most rapidly, the trees, for the most part, have stopped their 



