G2 
THE FLORIST AND POMOLOGIST. 
[ March, 
THE PHYLLOXERA AND ITS DESTRUCTION. 
JCCORDING to the published reports, 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, other remedies which had 
been tried were either without effect on the Plnjlloxera^ 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 monosulphides with 
the bisulphide of carbon, are either liquid or solid, and emit a powerful odour of 
sulphuretted hydrogen and bisulphide of carbon. The alkaline sulpho-carbonates 
in the solid state are of a beautiful reddish-yellow colour and deliquescent, but 
are not easily obtainable in that condition ; the sulpho-carbonate of barium can 
be easily procured, 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 sulphu¬ 
retted hydrogen and bisulphide of carbon. These two latter substances are 
gradually liberated, and as they have a very powerful effect on the Phylloxera^ 
one can understand that the sulpho-carbonate, placed in the ground, may prove, 
by its slow decomposition, a powerful insecticide. In the case of the sulpho- 
carbonate of potassium, over and above its toxic effect, it has a direct invigorating 
influence upon the Vine, as the carbonate of potassium is an excellent manure. 
The employment of the sulpho-carbonates as a means for the destruction of 
the Phylloxera was suggested to M. Dumas by the clearly-recognised need that 
there was of some substance that would evaporate less quickly than the bisulphide 
of carbon ; he saw that it was desirable to apply the insecticides in some com¬ 
bination which would fix them and only allow them to evaporate gradually, so 
that their action might continue long enough in any one place to infect with their 
vapours all the surrounding soil. 
But the task of eradicating the Phylloxera has by no means been accomplished 
by the mere discovery of the value for the purpose of these substances ; there is 
the further difficult}^ of applying them to the Vine in cultivation. One thing 
seems very certain, that in order to render the sulpho-carbonates practically 
efficacious in killing the insect, it is necessary to use water as the vehicle by which 
they may be brought to all the underground parts of the plant, and that the best 
time of year for their application is the winter or early spring, when the earth is 
still moist and the quantity of water necessary to be brought on to the ground by 
artificial means is consequently less. Mixed with lime in the proportion of tAvo to 
one, these sulpho-carbonates give a poAvder Avhich can be spread over the ground 
before the heavy rains,—that is, betAveen October and March, and which will 
probably prove itself very efficacious. 
The conclusion arrived at is that the efficacy of the sulpho-carbonates is 
