PROCEEDINGS, 1918 73 



White arsenic. 



White arsenic has long been known as an insecticide. In 

 1848 it was reported by George Gordon in the Journal of the 

 London Horticultural Society, as beirg valuable mixed with 

 sugar for the destruction of brown ants. It was tried many 

 times between 1860 and 1870 for the destruction of the potato 

 beetle, and although the beetles were killed, it always proved 

 so caustic to foliage that Paris green was used in preference.lt 

 was never used to any extent on foliage, but developed some- 

 what for making poisoned baits. 



White arsenic is at present used to a limited extent by the 

 grower for making arsenite of soda, while to the manufacture of 

 arsenicals it is the basis of all his products. White arseric is 

 used, as such, mixed with bran middlings, etz in a mash, to de- 

 stroy cutworms and grasshoppers. It is by far the cheapest 

 form of arsenic. 



In Nova Scotia white arsenic is hardly used at all. Recent 

 experiments have shown that it may possibly be of value in a 

 modified Bordeaux mixture. 



Bordeaux Mixture, 



The. origin of Bordeaux mixture, as its name implies, was in 

 France and in the grape growing country in which the city of 

 Bordeaux is situated. Its discovery is intimately associatad 

 with the history of the downy mildew of the grape. This de- 

 structive disease was of American origin, and was first observed 

 in France on American seedlings in 1878. It spread rapidly 

 and was so ruinous that many vineyards were almost destroyed. 

 In 1882 the mildew was particularly bad, but it was noticed 

 that there were certain vines situated along the highways which 

 were unattacked. Vineyardists in these localities had suffered 

 losses from the stealing of their grapes by children and travellers 

 and it had become their custom to sprinkle the vines along the 

 roadsides, with a mixture of lime and copper sulphate to give 

 them the appearance of being poisoned. The vines thus treat- 

 ed were the ones which remained free from the disease. This 

 observation lead to the development of Bordeaux mixture 

 through the energy of Prof. Millardet of the Faculty of Sciences 

 of Bordeaux, who commenced his experiments with copper 

 compounds in 1883. The use of Bordeaux mixture soon 

 spread through all countries, as it was shown to be capable of 



