Page:Popular Science Monthly Volume 5.djvu/178

166 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:

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;