30 



Wied., Rhagoletis •pomonella, Walsh, R. cingulata, Loew, R. fausta, 

 O.S., and Epochra canadensis, Loew, was tested for D. cucurhitae ; 10 

 kerosene traps were wired in different parts of an orchard, and 10,239 

 flies were captured in five weeks, of which only 36 were females ; 

 poisoned bait-spray was then applied to the trees once a w^eek for 

 the following five weeks, only 182 flies being caught in the kerosene 

 traps. In captivity the adults show a preference for diluted molasses, 

 especially during the fortnight before the egg-laying period ; poisoned 

 molasses sprayed on the food-plant when the flies are emerging should 

 therefore kill many of them. The poisoned bait was composed of : 

 brown sugar 2i lb., lead arsenate 5 oz., water 4 gal. ; the brown sugar 

 and lead arsenate were dissolved through cheese-cloth in cold water, 

 so as to eliminate foreign bodies, and the mixture was agitated with 

 a common brass spray pump. The text is freely illustrated and a 

 bibhography is appended. 



SiCAKD (L.). Etude de la bouillie bordelaise. Composition et prepa- 

 ration rationelle. [A study of Bordeaux mixture. Its proper 

 composition and preparation.] — Progres Agric. Vitic, 3IontpeUier, 

 xxxi, nos. 33-38; 16th, 23rd, 30th August; 6th, 13th, 20th 

 September 1914; pp. 211-217, 235-241, 263-266, 289-291, 

 304-309, 323-327. 



Chemists have not been eager to determine the actual composition 

 •of Bordeaux mixture, owing to the many technical difficulties involved. 

 Pickering more or less solved the question and in the present paper 

 it is the results of his researches which are brought to the notice of 

 vine-growers, together with those obtained by the author, the chief 

 chemist at the National School of Agriculture at Montpellier, with 

 the object of showing how Bordeaux mixtures more efficient than those 

 at present obtainable may be prepared. The principal facts resulting 

 from this study of the subject are as follows : — When a pure milk of 

 lime is very slowly poured into an energetically stirred solution of 

 copper sulphate (containing 1 kilo of pure copper sulphate), the 

 Bordeaux mixture obtained is acid as long as the total amount of 

 pure quicklime added is under 168-5 grammes. When the quantity 

 of lime reaches 168-5 grammes, all the copper is rendered insoluble. 

 The Bordeaux mixture is then neutral and without excess of lime. 

 Larger quantities of lime (from 168-5 to 225 grammes) produce a 

 neutral mixture with excess of lime. In this case the alkaline con- 

 dition which occurs immediately after an addition of lime does not 

 last, the time it takes to disappear increasing with the amount of the 

 total quantity of lime. If the weight of the lime exceeds 225 grammes, 

 a permanently alkaline Bordeaux mixture is produced. 



The reaction of the lime on the copper sulphate is very complex, 

 producing not only the calcic sulphate, but also a number of copper 

 compounds. These are either basic sulphates of copper or double 

 sulphates of copper and calcium or double hydrates of copper and 

 calcium. The formation of each of these compounds corresponds 

 with a given quantity of lime. If the copper sulphate solution con- 

 tains 1 kilo of pure copper sulphate, a quantity of lime inferior to 

 168-5 grammes will produce the basic sulphate of copper SOo, 3-5CuO ; 

 with 168-5 grammes of lime the tetracupric sulphate SOo, 4 CuO 



