524 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



The former caused more injury. The application of milk of lime to 

 sprayed trees did not prevent the liberation of copper. 



The application of milk of lime alone to the leaves caused no injury, 

 but a noticeable increase in the size of the leaves resulted. There are 

 several illustrations of the apparatus used in the field.— C. H. H. 



Bordeaux Spraying'. By Spencer U. Pickering, F.R.S. [Jour. Agr. 

 Sci. iii. (1908), p. 171). — The author recently investigated the composi- 

 tion of Bordeaux mixture and in the present communication describes 

 the changes which take place during its use. 



When lime is added to copper sulphate different basic sulphates are 

 formed, and these when sprayed on to foliage are decomposed by the 

 carbonic-acid gas of the air and form copper carbonate and some copper 

 sulphate, and to the formation of these the fungicidal power of the spray 

 is due. When lime is added in the form of lime water in just sufficient 

 quantities to precipitate the copper, a basic sulphate is produced which, on 

 decomposition, reproduces %5 per cent, of the copper sulphate taken, but 

 if the mixture has sufficient lime to render the mixture slightly alkaline, 

 a different basic sulphate, capable of reproducing only 10 per cent, 

 of the copper sulphate, is produced. When made in the ordinary way 

 (indeed, when the proportion of lime amounts to from 1*2 to 5 CaO 

 for each CuS0 4 taken) the same amount of copper sulphate will be 

 reproduced, but delay occurs owing to the excess lime having to be 

 converted into carbonate first. 



Later experiments, however, show that much more copper sulphate 

 than 25 per cent, is recoverable from Bordeaux mixture made with lime 

 water (the " Woburn Bordeaux," long used in Italy) owing to secondary 

 reactions bringing the amount recovered up to 40 per cent., while in the 

 case of ordinary Bordeaux mixture the usual 10 per cent, is not exceeded 

 through secondary reactions. 



Dried Bordeaux mixture differs in chemical composition from that 

 made in the ordinary way or with lime water, and is considered much 

 less efficient than the latter. 



The addition of treacle to the "Woburn Bordeaux" may perhaps 

 increase the rapidity with which the fungicidal copper sulphate is set 

 free, but with ordinary Bordeaux mixture the treacle must necessarily 

 have a detrimental effect. 



Where it is desired to use soda Bordeaux mixture, on account of the 

 less tendency to scorch foliage, the proportion in which it should be 

 used is 1-84 part of crystallized carbonate (ordinary washing soda) to 

 each part of copper sulphate. Its fungicidal action appears to be small, 

 and what it possesses seems to be due to the soluble copper which exists 

 for a short time (soon to be converted into malachite) in the mixture. 



F. J. C. 



Botanic Garden, Eastern Java. By M. Buysman (Die Gart. 

 p. 570, November 27, 1909).— The greatest hindrance against acclim- 

 atizing plants from other countries is the exceptional humidity, or 

 cather the heavy, lasting rain showers. Eain falls daily from the middle 

 of November till June or July, and the remaining months of the year 



