COPPER SULPHATE (BLUE VITEIOL). 201 



solutions containing oxychloride of copper obtained by precipitating 

 •copper sulphate with bleaching powder. These bouillies, studied by 

 Fairchild, consist of blue vitriol 2 lb., chloride of lime 3 lb., in 100 

 gallons of water, or of blue vitrol 2 lb., chloride of lime 4 lb., in 100 

 gallons of water. These bouillies, which like true Brunswick green, 

 CuCl^SCuO, 4H„0, contain a greater or less excess of chloride of lime, 

 produce very disastrous effects on the leaves. Compared with other 

 bouillies they are less adherent and less active against cryptogamic 

 ■diseases. Tried against Entomosporium mactdatum, Lev. (spots of 

 the leaves of the pear) they do not prevent the disease, and seriously 

 •damage the leaves. 



89. Copper Sulphite, CuSOy. — Preparation of the Bouillie. — 

 Dissolve separately 2 lb. of blue vitriol and 2 lb. of sulphite of soda in 

 •5 gallons of water; mix the two solutions and add thereto a solution of 

 1 lb. of bicarbonate of soda, make up with water to 20 gallons. 



Properties. — Copper sulphite is a green precipitate sufficiently 

 soluble in water to act very energetically on the spores of all crypto- 

 gamic fungi. Unfortunately it possesses the fault of all salts of 

 sulphurous acid, that of burning the organs of the plant attacked. 



Use. — Copper sulphite bouillie has been recommended against 

 oidium and peronospora. For this purpose about five sprayings a year 

 are required, the first of which is with a I'O per cent bouillie, and the 

 succeeding with a 1-5 per cent bouillie. Neither sulphurous acid salts 

 nor free sulphurous acid being capable of replacing sulphur in the 

 struggle against oidium, it is doubtful if copper sulphite possesses the 

 properties required to combat these two parasites of the vine simul- 

 taneously. Moreover, its use has not spread, owing to its corrosive 

 action on the leaves, an action which counterbalances its i-emarkable 

 anticryptogamic properties. 



90. Sulphate of Copper, CuSO^SHoO (blue vitriol, blue copperas). 

 — Preparation. — By roasting mineral sulphides of copper in reverber- 

 atory furnaces and in a highly oxidizing current of air. The mass 

 obtained is lixiviated with hot water and the blue liquor crystallized. 



Properties. — Blue vitriol prepared thus is often impure.^ It is thus 

 less active as an anticryptogamic. That used to combat plant diseases 

 is prepared by oxidizing copper turnings in a reverberatory furnace and 

 dissolving the product formed in sulphuric acid. Crystals of copper 

 sulphate are dark blue, transparent, with a styptic taste. They 

 effloresce slightly in the air because above 15° C. they lose a part of, and 

 at 100' C. the whole of their water of crystallization. One hundred lb. of 

 water dissolve 36 lb. (10 gallons) of blue vitriol at 19° C.,88 lb. at 50° C, 

 and 213 lb. at 104'" C. In medicine its emetic properties are utilized 

 in doses of 25-30 centigrammes. In croup it is administered even to 



1 It in fact often contains green vitriol and zinc sulphate. If it be desired to 

 detect these the blue vitriol is dissolved in water, and carbonate of soda or milk of 

 lime added. Pure blue vitriol gives a sky-blue precipitate, if it contains green 

 vitriol it gives a dirty-blue precipitate, if it contains zinc sulphate the precipitate is 

 of a pale bluish colour. [Peroxidize the solution with nitric acid, add large excess 

 of ammonia or potash (KHO), filter, a brown residue = iron. The agricultural quality 

 of blue vitriol contains up to 50 per cent or more of green vitriol.— Tii.] 



