STATE HORTICULTURAL SOCIETY. 205 



it must destroy the insect, and it must not damage, to any great extent, 

 the vine. But, further, it is not sufficient that when put in close contact 

 with the roots of a plant — as in a pot — it should prove fatal to the insect : 

 it is necessary, if the remedy is to be of real practical value, that it should 

 reach and destroy the Ph)iloxera on all the parts attacked by it in vines 

 which are planted out in the open air. This is a real difficulty to over- 

 come, as the remedy, be it in the form of solution or of vapor, cannot 

 easily permeate the soil, sometimes clayey, sometimes sandy, on which 

 the vine is growing, so as to reach and act upon the smaller root branches 

 whose nutrition the Phylloxera diverts into itself. 



"M. Mouillefert, a professor at the School of Agriculture at Grignon, 

 was the gentleman delegated by the Academy of Sciences to make the 

 necessary experiments for the purpose of determining what agent was the 

 most practically applicable to the destruction of the Phylloxera ; and the 

 account of the numerous substances employed by him, with varying 

 results, fills no less than two hundred pages of a memorial presented to 

 the Acadeiiiy of Sciences. It is not our intention here to give more than 

 a brief resume of the results at which he arrived. 



" He divides the substances used by him into seven groups, the first 

 of which was composed of manures of various kinds, such as guano, super- 

 phosphates, farm muck, etc. ; the second, of neutral substances, as water, 

 soot and sand ; the third, of alkalies, as ammonia and soda; the fourth, 

 of saline products, among which were the sulphates of iron, copper, 

 zinc, potassium and ammonia, alum and sea salt ; the fifth, of vegetable 

 essences and products, as decoctions of hemp, datura, absinthe, valerian 

 and tobacco; the sixth, of empyreumatic products; and the seventh, of 

 sulphur compounds. It was with some of the substances contained in 

 this last group that really satisfactory results were obtained ; and it is to 

 M. Dumas, the Permanent Secretary of the French Academy of Sciences, 

 that the credit is due for suggesting the employment of the alkaline 

 sulpho-carbonates of potassium and sodium, and those of barium and 

 calcium. All the other classes of remedies mentioned above were either 

 without effect on the Phylloxera, or, in destroying it, also destroyed or 

 damaged the vine. 



"The sulpho-carbonates, which were carefully studied by the great 

 Swedish chemist, Berzelius, are obtained by combining the alkaline mono- 

 sulphides with the bi-sulphide of carbon, are either liquid or solid, and 

 emit a powerful odor of sulphuretted hydrogen and bi-snlphide of carbon. 



"The alkaline sulpho-carbonates, in the solid state, are of a beautiful 

 reddish-yellow color and deliquescent, but are not easily obtainable in 

 that condition ; the sulpho-carbonate of barium can be easily produced, 

 however, in a solid state, and presents the appearance of a yellow powder, 

 but little soluble in water. The sulpho-carbonates decompose under the 

 influence of carbonic acid, forming a carbonate, and evolving sulphuretted 

 hydrogen and bi-sulphide of carbon. These two latter substances are 

 gradually liberated, and as they have a very powerful effeet on the Phyl- 

 loxera, one can understand that the sulpho-carbonate, placed in the 

 ground, may prove, by its slow decomposition, a powerful insecticide. 



