COPPER SULPHATE (BLUE VITEIOL). 



203 



number of wines the average amount of copper does not reach 

 one-hundredth of a milhgi'amme. This amount of copper, contained 

 in wines, comparatively small in comparison with that which enters 

 into the vat, arises from the fact that the copper remains insoluble in 

 the lees. To prove it, it suffices to place a handful of blue vitriol in 

 the vat ; the copper will remain in the lees and not pass into the wine. 

 The tables prepared by Crolas, Eaulin, as well as by Millardet, show 

 this fact decisively. 



TABLE XXY.—Shoiving the Distribution of Insecticidal and Anticryptogamic 

 Copjjei- betireen Wine, Lees, etc. 



The different parts of the vine treated by a copper bouillie contain the 

 following amounts of copper in milligrammes per kilogramme : leaves 

 24-9-95-5; stem and wood, 5-8; grapes, 15-9-18-6 ; marc, 11-1-29-9; 

 wort, 1-0-2-2; wine, O'l. The amount of copper entrained into the 

 wine is so small that it does not even interfere with the fermentation. 

 The development of the ferments is not hindered up to 0-3 gramme 

 of blue vitriol per litre (Rommier), a dose, therefore, which can never 

 occur in wine. It must, therefore, be admitted, that before the action 

 of copper can make itself felt, a man must absorb several hundred 

 litres of wine a day. 



Action of Blue Vitriol on Plants.— To ascertain the action of a. 

 soluble salt on a plant the latter is grown in an artificial medium con- 

 taining a known dose of the salt to be examined. Haselhoff found 

 that the greater number of plants suffered in such conditions from a 

 small dose of blue vitriol. According to him the dose of O'OOl per cent is 

 injurious in almost all cases, but the deadly action of blue vitriol al- 

 ready shows itself in presence of 0-0005 per cent with certain plants^ 

 and even with O'OOOll per cent (Devaux). Normal growth is im- 

 possible, except in presence of much weaker doses of blue vitriol. 

 Thus peas grow normally in a 0-00005-0-000001 per cent solution. 

 Maize grows in a O-000005-O-OOOOOOl per cent solution. Grain only 

 stands very weak doses of sulphate of copper; the young plant is 

 killed by "0-004875 per cent of copper bromide, 0-005 per cent of 

 copper chloride, 0*00555 per cent of copper sulphate, 0-005714 per 

 cent . of acetate of copper, 0-0061 per cent of copper nitrate. It 

 follows from these experiments that copper salts are violent poisons to 

 plants when the roots are in presence of their solutions. Coupin's 



