14 SPICES 



CHAP. 



follows : It is in the form of a wooden box about 1 ft. square, 

 the bottom of which is formed of hard wood, with a hole bored 

 through it, into which a piece of gasplpe, 1J in. or 2 in. in 

 diameter and from 6 in. to 9 in. long, is fitted. 



The box is, of course, open at the top. Fitting just inside 

 this box is a second and lighter box, also open at the top, and 

 having an overhanging strip nailed round the top which supports 

 it. The bottom of this inner box should be made so as to slope 

 at an angle of about 30, and should be made of fine copper 

 gauze. The slanting bottom makes it harder to clog, and the 

 inner box, being removable, can be inverted and washed in a 

 tub of water. Bordeaux mixture, if properly strained, will pass 

 easily through nozzles which throw the finest " misty " spray, 

 while if not properly strained, frequent clogging of the nozzle 

 will result. 



If the lime used is freshly burnt (and it must never be for- 

 gotten that air-slaked lime is useless for making Bordeaux 

 mixture) and carefully weighed out, there is no need to test the 

 mixture before using it. When using " stock solutions," it is a 

 good plan to apply a test at the first mixing. A rough test 

 consists in immersing a clean iron wire or French nail in the 

 Bordeaux mixture for one minute ; if safe to use, the mixture 

 does not affect the nail ; while if unsafe, a copper-plated appear- 

 ance is given to it. A more delicate and quite simple test is 

 as follows: procure from a chemist a 10 per cent solution of 

 ferrocyanide of potassium (which is a poison) and pour a little 

 of this into a white saucer; then drop a few drops of the 

 Bordeaux mixture into the ferrocyanide of potassium. No 

 change of colour occurs if the mixture is safe to use, while a 

 cloudy reddish-brown discoloration (very easy to see) occurs 

 immediately if the mixture is unsafe to use. An unsafe mixture 

 can be made safe by adding more " milk-of-lime " until it passes 

 the test. 



In spraying there is no need whatever to add anything to 

 the Bordeaux mixture with the object of making it adhere 

 better; soap is quite unnecessary and should never be used, 

 and treacle is useless. The nature of the precipitate which 

 constitutes Bordeaux mixture causes it, when applied in a 

 "misty" spray (see below), to adhere most intimately to the 

 part sprayed. 



The Application of Bordeaux Mixture. The best type of 

 spraying machine for spraying with Bordeaux mixture depends 

 to a large extent on such circumstances as the height of the 

 trees, and whether they are grown in a plantation or in an 

 orchard. But the chief point that requires to be emphasised 



