xliV PROCEEDINGS OF THE ROYAL HORTICULTURAL SOCIETY. 



settle. The Tomatos were syringed with the clear liquid. The 

 effect has been disastrous, the stems and leaves having in every 

 case been burnt, and the lower leaves had to be removed. Some 

 of the same solution falling also on Vine leaves produced red 

 spots (burns). Now this solution, prepared as above described, 

 was simply a dilute solution of sulphate of copper, containing 

 about one ounce of sulphate of copper in the gallon ; so that the 

 whole of the process for preparing the solution was entirely 

 useless, and the product, viz. the hydrated oxide of copper 

 .thrown down by the lime, was allowed to settle and was not 

 used ; in fact, if you had taken an ounce of copper sulphate and 

 dissolved it in a gallon of water you would have got a solution of 

 exactly the same kind as the one which was used. In the letter 

 from M. Cornu, which you have sent me, I see it is stated that this 

 hydrated oxide of copper is the active agent, and that the copper 

 ought to be totally precipitated from the liquid. At the same 

 time, I think that the nature and the preparation of this bouillie 

 bordelaise has not generally been clearly stated and understood. 

 I suppose I may assume that this hydrated oxide of copper is 

 the substance which it is desired to prepare, but it will be a 

 matter of the greatest importance as to whether it is suspended 

 in a solution of sulphate of copper, or in lime water, or in pure 

 water ; all of which cases are possible according to the proportions 

 of the materials used. In the case of Chiswick there was a 

 deficiency of lime, and hence the copper sulphate remained in 

 solution. To get rid of the sulphate of copper, which appears to 

 have acted so injuriously, the instructions should be to continue 

 the addition of lime till the liquid just ceased to have a blue 

 •colour when a depth of 2 or 3 inches is looked through. I 

 should think that the different results which have been obtained 

 by different experimenters may be to a great extent accounted 

 for by the want of an exact description of how the bouillie 

 bordelaise was to be made and how it should be used." 



The following are extracts from M. Cornu's letter received by 

 Dr. Masters (from the Museum d'Histoire Naturelle, Paris) : 

 "The proportions of the bouillie bordelaise vary from 3 to 4 

 kilogrammes of sulphate of copper, with 3 to 4 of quicklime, 

 and 100 kilogrammes or litres of water [1 kil. = 2^ lbs. ; 100 

 litres = 22 gallons]. It is better to have less copper than lime, 

 so that all of the former may be precipitated. The copper salt 



