INSECTICIDES, FUNGICIDES, ETC. 183 



Sundry preparations of the basic sulphates of copper in the 

 dried form are used as fungicides, being either mixed with water 

 before use, or blown on to the plants as powders. Their action 

 is substantially the same as that of the undried preparations, but, 

 when mixed with water, they do not reproduce a suspension at 

 all comparable with that obtained with a freshly prepared, 

 undried precipitate, and all of them, it may be noted, contain 

 a considerable amount of their copper in the soluble form to 

 start with (XI, 81). 



Bordeaux mixture or any of the basic sulphates of copper 

 may be mixed with Paris green, lead arsenate or nicotine, so as 

 to give them insecticidal properties, and these additions do not 

 interfere with the fungicidal value of the copper. The basic 

 sulphates Bordeaux paste may also be emulsified with 

 paraffin, as has been mentioned on p. 160, with the same result. 

 Ordinary Bordeaux mixture does not emulsify the oil satisfactorily, 

 owing to the presence of the grosser particles of lime in it. 



(2) Burgundy Mixture, Soda Bordeaux (XI, 86, App.) 



Sulphate of copper, precipitated by carbonate of soda, and 

 mixed with molasses, was used in France in 1890. More recently 

 a similar mixture, but without the molasses, has been advo- 

 cated as a substitute for ordinary Bordeaux mixture, and has 

 received the above names. It has been used somewhat ex- 

 tensively, but without any very good results, in New Zealand, 

 and, with better results, for potato-spraying, by the Board of 

 Agriculture and Technical Instruction in Ireland. Following this 

 lead, the Food Production Department of the Board of Agri- 

 culture and Fisheries in England has, since 1916, advocated it 

 for potato -spraying, to the exclusion of all other materials. The 

 proportions of the ingredients recommended by them for making 

 the mixture i Ib. of crystallised sulphate of copper to 1-15 Ibs. of 

 sodium carbonate l in 5 gallons of water are, however, based on 

 the supposition that the carbonate of copper formed is a substance 

 which every student of elementary chemistry knows to be 

 incapable of existing, namely, CuCO 3 , and in ignorance of the 



1 The proportion recommended by the Irish Board was rather higher, 

 i : 1-25, and the English Board adopted these proportion in a leaflet 

 (F.P. I42/H) published in 1918; at the same time they reduced the 

 strength of the mixture recommended to i Ib. of sulphate to ten gallons 

 of water. As no reasons are given for these alterations, they cannot 

 be regarded as final, and it has, therefore, not been considered necessary 

 to alter the above text so as to harmonise with the recommendations of 

 the moment. 



