< Page:Popular Science Monthly Volume 5.djvu
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THE POPULAR SCIENCE MONTHLY.

tage over a liquid, as it will more effectually permeate the soil and reach the lice. The following is the method of procedure in their own words:

"Make three holes around the vine, the depth to vary according to nature of soil, but generally about 21⁄2 feet (80 centimetres). Hitherto we have made these holes with a pointed iron bar, driven by a maul. When the hole is made the bar is withdrawn, and a tube, furnished with a funnel at one end, is inserted in its place. About two ounces of sulphuret of carbon are then poured into the tube, which is immediately corked.... The vapor of this sulphuret of carbon permeates the soil, and impregnates all the roots of the vine. The gas engendered is not, like the liquid itself, fatal to the vine, but invigorates it. Its effects are, however, sure death to the insect, and, if a vine is examined eight days after the treatment, the lice are found dead and carbonized. At the end of fifteen days nothing but the effects of the lice is seen. Long and corroborative experience has demonstrated that about four ounces (100 grammes) of the liquid is sufficient for an ordinary vine; but sprinkling on the surface must be carefully avoided, as it is then very injurious to the vine; whereas as much as a pound may be made to penetrate the soil without injury to the roots."

Soon after the announcement of this method, I employed it as a test on three vines, which I knew to be infested with Phylloxera, using three ounces to the first, six ounces to the second, and nine ounces to the third, the soil being a light clayey loam. At the end of twelve days I found plenty of living lice on the first and second vines, and such were found long afterward, though in small numbers, up to the time of the freezing of the ground. On the third vine all the lice were evidently charred, but the vine was also plainly injured, as the leaves wilted as though they had been scorched, though, whether from the vapor issuing from the ground, or from the injury to the root, it was impossible to determine—I think, however, from the former, as the larger roots were yet alive late in the season, and the vine seems, at this writing, to be living.

After very careful and laborious experiments made in France at different points, and on different kinds of soil, by a commission specially charged with studying the action of this chemical, under the method proposed by Messrs. Monestier, Lautand, and D'Ortoman, it fails to fulfill the sanguine expectations of these gentlemen. The liquid is costly, its application is laborious, and there is great difficulty in reaching and killing all the lice without injuring the vine. Great caution must also be had in its use, as it is extremely volatile and explosive, the vapor igniting at a great distance from the vessel containing it.

While, therefore, not very satisfactory results have followed the use of pure insecticides, the application of fertilizers, intended to invigorate the vie, and at the same time injure the lice, has been more productive of good. Especially has this been the case with fertilizers rich in potassic salts and nitrogenous compounds, such as urine.

Sulphuret of potassium, dissolved in liquid manure; alkalino-sul-

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