50 INSECTICIDES, FUNGICIDES, AND WEED KILLERS. 



the plants longer ai^ainst new inva-sions of oidiuin. But this opinion 

 is not accepted, and it is generally believed that sulphur does not act 

 in the presence of common salt. Pollacci and P. Viala condemn these 

 mixtures, the first, because he believes that sulphur is not oxidized in 

 the presence of copper salts, the second, bec'ause the experiments 

 made at the Montpellier schools showed that these mixtures could 

 neither prevent nor arrest the oidium and mildew. Mach and Mares 

 agree upon that point, and this is the explanation : Copper salts have, 

 in fact, the drawback of catching the vapours of sulphur, converting 

 them into insoluble and inactive copper sulphide. If it be taken that 

 sulphur acts by its vapours, it is evident that the action of the product 

 is destroyed. These remarks are also of value in regulating the 

 double treatment with sulphur and cupric bouillies. Since the intro- 

 duction into viticultural practice of sulphating against mildew and 

 black rot, the question of ascertaining whether sulphuring should be 

 done before sulphating, or vice versa, has been often discussed. 

 Laurent advises to precede the first sulphuring by the first sulphating, 

 the second sulphating being done after flowering. But as the sulphur 

 acts for four to five days, it is well to let this interval elapse between 

 sulphuring and sulphating, so that these two treatments do not mutually 

 destroy the effects of each other. 



Drawbacks to Sulphuring. — Workmen engaged in sulphuring 

 with sublimed sulphur sometimes have bad eyes, especially if they do 

 not take the precaution to work with the back to the wind. To obviate 

 this drawback, it is well to make them wear spectacles with cloth side- 

 pieces, and to make them bathe the eyes several times a day with fresh 

 water. Sulphur also gives sometimes a slight taste to the wine, owdng 

 to hydrogen sulphide, formed during fermentation. But this drawback 

 is always caused by too dilatory sulphuring. If the wine still contains 

 sugar, and is fermenting, it must be drawn off after fining in a cool 

 cellar. If it does not contain sugar and already drawn off, it must 

 be protected from any new production of hydrogen sulphide by the 

 following treatment : In the case of wine with a feeble taste, one or 

 two drawings off, during which the liquid is allowed to flow in a thin 

 stream into a tank, may suffice to let the hydrogen sulphide escape 

 into the air. L. Mathieu advises to run the wine in a stream over a 

 plate of polished copper, so that it runs into a film : one part of the 

 gas escapes into the air, the other is fixed by the copper. The copper 

 plate must be cleaned from time to time with emery paper when it 

 is blackened. If these methods do not suffice, sulphurous acid must be 

 added to the wine as bisulphite of potash (metabisulphite of potash), 

 about 10 grammes per hectolitre, say 7 grains per gallon. The two 

 gases mutually destroy each other with the deposition of sulphur, 

 which simple fining after a few days will completely carry down into 

 the lees. By using for the last operation only 40 kilogrammes of 

 sublimed sulphur per hectare (35'2 lb. per acre) or a stronger dose of 

 Apt sulphur or any other product of low sulphur content, this draw- 

 back need not be feared. 



Oidium FragaricB, Harz (oidium of the strawberry). — Sulphuring 



