18fi INSECTICIDES, FUNGICIDES, AND WEED KILLERS. 



to kill it, and that a dose of 1 gramme of cyanide, say 15 grains, 

 per stock was capable of injuring it. Attempts to replace carbon 

 disulphide by potassium cyanide, moi-e especially in Italy, have given 

 unfavourable results. 



Disinfection of the Vine. — Whilst potassium cyanide has been 

 abandoned in the different cases described above, this product is used 

 with success to disinfect vines intended for exportation, or coming 

 from a contaminated country. This process, introduced at the Nice 

 Agronomical Station by Koenig, yields perfect results. It is in common 

 use, moreover, in Tuscany. Sannino advises to replace the disinfectant 

 chambers by baths containing a 0'5 per cent solution, and in which 

 the vines are immersed in winter for two hours. The same process is 

 used to destroy cochineal on fruit trees. 



Diaspines {Diaspinece). — Coquillet uses prussic acid as a specific 

 against diaspinea, cochineals (scale insects). 



This product may be used against all these dangerous parasites, of 

 which the following are the chief : Asjndiotus perniciosus, Comstock 

 . (San Jose louse), injurious to apple-trees in America. Asjndiotus ostrea- 

 formis, Curtis. Oyster scale, very widely distributed on apple-trees, 

 plum-trees, pear-trees, and peach-trees. Aspidiotus aurantii, Maskell. 

 Cochineal injurious to orange-trees. Diasjns ostreaformis, sign. s. 

 fallax, Horvath. Cochineal injurious to apple, pear, plum, and j)each 

 trees. Mytilaspis poviorum, Beche. Mussel scale, resembling the pre- 

 ceding and living on same plants. Lecanium persica (peach kermes) ; 

 Lecanium hesperidium (olive kermes) ; Pulvinaria ■oitis (vine cochi- 

 neal) ; Cereplastes msci (fig cochineal) ; Dactylopius citri (lemon-tree 

 cochineal) ; Lecanium amygdali (almond-tree cochineal). Coquillet, 

 Johnson, Webber, Wait, and Howard, American entomologists, are 

 unanimous in praising the good effects of the use of potassium cyanide, 

 and that insecticide is in current use in their country. So that the 

 result may be complete, the treatment should last three-quarters of an 

 hour, and the operation done in wanter as indicated above. 



Earth-worms are less resistant than plants to spraying with a dilute 

 solution of potassium cyanide and they may be got rid of by this 

 means. 



38. Potassium Sulphocyanide, KCNS. — Preparation. — Sulpho- 

 cyanides are produced by the action of sulphur, or a body capable of 

 producing sulphur, on cyanides. Potassium cyanide, or even yellow 

 prussiate, fused with sulphur is converted into potassium sulphocyanide 

 thus : 46 grammes of yellow prussiate are heated to pasty fusion with 

 17 grammes of potash and 32 grammes of sulphur ; after cooling, the 

 mass is crushed, treated with boiling alcohol, filtered, and evaporated. 



Properties. — If sulphocyanide has certain analogies with cyanide 

 it is far from being as poisonous. It paralyses the action of the heart 

 (CI. Bernard and Pelikau). 



Action on Plants. — Mouillefert treated several plants with 

 KCNS :— 



(1) Experiments on Adventitious Plant Weeds. — In a space 16 

 inches square on which there were young plants of Mercurialis annua, 

 Amarantus blitum, Senecio vulgaris, SoncJms oleraceus, Polygonum 



