SCIENTIFIC COMMITTEE, JULY 26. 



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must first be dissolved in water (10 litres), and the lime also 

 separately in 20 litres ; the two must then be mixed together.. 

 Under these conditions the copper is reduced to the state of a 

 hydrated oxide, which is quite or nearly insoluble, and does not 

 bum the leaves. The lime also effects a mechanical adherence 

 of the copper salt to the surface of the leaves. The hydrated 

 oxide of copper becomes soluble under the influence of organic 

 acids contained in small quantities in the liquid in contact with 

 the vegetative organs. There is an elective property in cellulose 

 membranes for salts of copper, and the natural explanation 

 which follows from this fact is : first, that the Peronospora is 

 killed by the salt ; and, secondly, that the spores cannot germi- 

 nate upon leaves the membrane of which has imbibed the copper 

 salt. Leaves which have thus received the mixture are not 

 invaded by the Peronospora, while adjacent leaves are less easily 

 attacked. It has been observed in Bourgoyne that the Vines 

 were much less attacked by the Peronospora, the props of which 

 had been treated with the sulphate of copper, than those not so 

 treated. Hence it is advisable to soak all the objects which 

 surround the plants, especially the props or supports, &c, in the 

 bouillie bordelaise, as well as the walls, soil, pots, &c. The 

 author finally suggests the trial of copper sulphide finely 

 pulverised and scattered over the borders, plants, &c." With 

 reference to this last-mentioned suggestion of M. Cornu, Professor 

 Church observed that copper pyrites in fine powder suspended in 

 mine water has been proved to be most injurious to young grass 

 in water meadows. Free sulphuric acid and basic sulphate of 

 copper and iron were produced, the acid being the chief 

 destructive agent. 



Black Rice from Burmah. — Professor Church announced his 

 discovery of the occurrence of a red pigment in the grain of the 

 Black Eice of Burmah. A sample of this remarkable variety of 

 Eice was recently handed to Prof. Church for chemical analysis 

 by the Director of the Eoyal Gardens, Kew. It was an imper- 

 fectly decorticated sample, most of the grains still retaining portions 

 of the dark-coloured pericarp. Plunged into slightly acidulated 

 alcohol the pigment dissolved with a magnificent crimson colour; 

 and proved to be identical with one of the most widely diffused: 

 and best known of vegetable colouring matters. This is the 

 compound represented by the empirical formula, C 2 oH 20 O r o 



