314 INSECTICIDES, FUNGICIDES, AND WEED KILLERS. 



which protect them, with methylated spirit, which is then U^ihted. Reh 

 found that alcohol does not kill coccides after two hours' action. 



117. Amylic Alcohol, Cr,HjjOH. — Preparation. — Crude ordinary- 

 alcohol always contains a certain proportion of amylic alcohol, 

 especially if from the fermentation of potatoes. Amylic alcohol i-esults 

 from the secondary fermentation due to special ferments. 



Properties. — Crude amylic alcohol used in agriculture is a colour- 

 less fluid with a sweetish smell which hoils between 129° C. and 132° 

 C. It is not perceptibly soluble in water, but it dissolves in ordinary 

 alcohol.^ 



Action on Plants. — It is more poisonous to plants than ordinary 

 alcohol. Mixtures of soft soap and amylic alcohol cannot always be 

 used with impunity on plants without killin<f them (Fleischer). But 

 this is greatly due to the action of the soft soap on the leaves and the 

 young shoots of which a solution of 1-32 per cent strength produces 

 effects followed by death, and of which a solution of 0"66 per cent 

 injures plant growth considerably. 



Action on Insects. — Amylic alcohol alone is less poisonous than 

 its mixtures with soft soap. It does not kill the caterpillar of the 

 cochylis. These mixtures have, however, a very categoric action on 

 solt-skinned insects, such as plant lice and caterpillars, and are of uni- 

 versal use ; they have a better action than aqueous insecticides, because 

 they soften the insects touched. Used alone on the cankers of apple- 

 trees produced by the woolly aphis they destroy it. Spraying with a 

 mixture of water and 15 per cent amyl alcohol has been used to re- 

 move from meadows the laying females of the cockchafer. 



Use. — The greater part of the insecticides of commerce are mixtures 

 of amylic alcohol, soft soap, and an insecticide substance such as 

 pyrethra powder, tobacco, etc. Only known insecticides need be 

 quoted: " Nessler's,'' "Aphidin,"' " Antivermin," " Amylocarbol " in 

 Germany ; " Knadolin " in Switzerland ; Fichet's insecticide in France 

 recommended and recommendable for the destruction of plant lice and 

 caterpillars. Their effects on these insects are indisputable. The 

 following are the compositions of some of these insecticides : — 



TABLE LXII. — Shoiving the Coinpositio?!, of Nessler's hisecticides. 



Lb. Lb. Lb. 



Soft Poap 4 30 5 



Amyl alcohol 5 32 10 



Ordinary alcohol 20 —20 



Tobacco extract ..... 6 — - — 



rotassium sulphide — 2 — 



Water (in gallons) 10 10 — 



Knadolin. — Soft soap 40 lb., amyl alcohol 60 lb., nitrobenzene 



1 Translator's Note. — Amylic alcohol is a most unpleasant substance to handle. 

 A piece of canvas or an old straw hat coated with a varnish in which amyl alcohol 

 has been used to dissolve the resin used in the manufacture of the varnish should 

 drive off all insects from the neighbourhood. The least trace of amyl alcohol in the 

 air causes coughing of a most irritating nature, and an insecticide in which amyl 

 alcohol has been used can readily be detected by this means. As the boiling-point 

 of amyl alcohol is some 32° C. higher than that of water, it will readily be seen that 

 its irritating vapour is persistent if not permanent. 



