ID Nov., 19JO.] Luiic-watjr Bo/dtdux for Spraying 



73* 



the copper is entirely insoluble to start with, it is gradually rendered 

 soluble by means of the carbonic acid in the air, and some of it curiously 

 enough is brought l)ack to the condition of sulphate of copper with which 

 we startei.l. 



The practical result of this investigation is that lime-water is recom- 

 mended instead of milk of lime and the proportion of lime-water to copper 

 sulphate has been approximately determined, so as to yield the maximum 

 of efficiency with the minimum of the copper salt. In addition to this, 

 Pickering has succeeded in preparing a paste known commercially as- 

 Woburn Hordeaux Paste, " which when dilute(l with water is practically 

 identical, both chemically and physically, with tiie freshly made Wobum 

 Bordeaux, except that it contains no excess of lime." The paste is 

 patented, but the formula for the preparation of the fresh material mav 



THE SPRAYER A 1 W UKK. 



The use of lime-water in the preparation of Bordeaux mixture is by no- 

 means new. as it has been constantly used in Italv since 1886 with verv 

 good results, when it was first recommended by Profes.sor Cavazza. 



The latest formula for 50 gallons is approximately as follows: — ■ 



Copper sul]>h:ite, 10 ozs. 



Lime-water, 8^ {^'allons. 



Waier to make uj) to 50 <jallons. 



The standard formula for Bordeaux mixture generally used here is 

 6.4.50 or 6 lbs. copjjer sulphate and 4 lbs. quicklime to 50 gallons of 

 water, but with the sulistitution of lime-water in definite proportions for 

 milk of lime, the copper sulphate is reduced in amount from 6 lbs. to 

 10 o/s. for 50 gallons. 



Action of Bordeaux Mixture as a Fungicide. 

 How it acts is not certainly known, although there is a considerable 

 amount of literature on the subject, and it will only be generally and 

 briefly I'eferred to here. It mav either act directly l)y destroying the 

 fungus or its spores, or indirectly l)y iirexenting the germination of the 

 spores. The carbonate of copi^er which is formed has a protecti\e 



