Bordeaux Mixture Copper Carbonate 213 



Dissolve it in a pint of water, and label the bottle "Poison." 

 The needed amount of lime for making Bordeaux is then esti- 

 mated, instead of calculated, when taken from the stock, and 

 enough is added to satisfy the ferro- cyanide test. This test is 

 made by taking out a little of the Bordeaux in a small dish and 

 adding to it a drop of the ferro -cyanide solution. If a reddish 

 brown color appears more lime is needed, and it should be added 

 until no change in color takes place. It is even wise to use 

 more lime than is needed to satisfy the test. An excess of lime 

 is not injurious and probably is beneficial. 



Carbonate of copper. A good fungicide can be made by dis- 

 solving copper and ammonia and then diluting the solution with 

 water. This material has the great advantage over Bordeaux mix- 

 ture of not discoloring the foliage or fruit. It is therefore a 

 useful fungicide when it is needed to apply late in the season 

 when the fruit is nearly grown, or when it is desired to spray 

 plants that are used for ornamental effects. The material does 

 not adhere to the foliage as long as Bordeaux mixture, however, 

 and for that reason it does not retain its efficiency and is not so 

 much used. The standard fungicide is Bordeaux mixture; the 

 incidental one is carbonate of copper. 



The carbonate of copper may be dissolved at the rate of 

 an ounce in one pint to one quart of ammonia. The amount 

 of ammonia required will depend upon its strength. It is well 

 to use only enough ammonia to dissolve the copper, for the free 

 ammonia is likely to injure foliage. If the very strong ammonia 

 can be secured (that which is known as 26 Beaume"), the solu- 

 tion should be diluted with seven or eight times its volume of 

 water. This stock solution may be kept indefinitely in a tightly 

 corked bottle. When wanted for use, it should be diluted with 

 water at the rate of one ounec of carbonate of copper to eight to 

 twenty gallons of water. This makes a clear, bluish liquid, which 

 is as easily applied as the water itself. The addition of lime to 

 make the material adhere has not been very successful. The 

 carbonate of copper may be made at home by treating sulfate 

 of copper with sal soda ; but unless one wants it in large quant- 

 ity, it is better to buy. 



