CHAPTER XXIII. 



CARBON COMPOUNDS (coniin«e(i)— NITROBENZENE— CARBOLIC ACID- 

 PICRIC ACID— CRESOL — SAPOCARBOL — CREOSOTE— CREOLINES— 

 LYSOL— POTASSIUM DINITRO-CRESYLATE—THYMOL-3-NAPHTHOL 

 METHYL VIOLET. 



131. Nitrobenzene, CcH^NOo. — Preparation. — By pouring very 

 slowly, whilst stirring, 1 part of benzene into a cold mixture of 2 parts 

 of nitric acid of 40° B., and 2 parts of sulphuric acid of 66° B. When 

 nitrobenzene is formed water is added till it separates. It is decanted 

 and washed several times with pure water, then with water to which 

 a little carbonate of soda has been added. 



Properties. — Nitrobenzene is a yellowish liquid boiling at 213° C, 

 of a sweet taste, having the smell of bitter almonds. It is insoluble in 

 water, but soluble in alcohol, benzene, and oils. It is poisonous 

 (Olivier and Bergeron) ; the poisonous symptoms are the same as those 

 produced by aniline cyanose. The fatal dose for a man is 8-9 drops 

 (Letheby), 20 drops (Bardt). 



Action on Plants. — The experiments of Papasogli, Targioni-Toz- 

 zetti, and Del Quercio, have shown that soapy emulsions containing 

 0"5-0"75 per cent of nitrobenzene, and soapy and alcoholic emulsions 

 containing 0-25-0-5 per cent, are not injurious to plants. Zechini and 

 Silva found, on the other hand, that a 2 per cent nitrobenzene emul- 

 sion is very injurious to the vine. 



Action on Insects. — Nitrobenzene poisons insects. From the 

 author's experiments the nitro group would appear to increase appreci- 

 ably, and in a general manner, the toxicity of aromatic compounds. 

 Papasogli found that a milligram of nitrobenzene, evaporated under 

 a cloche, killed all the eggs of the fly and of Bomhyx Mori. According 

 to the author's experiments nitrobenzene prevents the hatching of 

 chrysalides. 



Use. — Papasogli recommends to destroy soft-skinned insects and 

 plant lice by an emulsion prepared thus : Dissolve 50 lb. of nitro- 

 benzene in 150 lb. of amyl alcohol, and add thereto 100 lb. of soft soap. 

 This insecticide is thinned down before use, and according to the 

 sensitiveness of the plant, with 10-20 parts of water, so as to get an 

 emulsion containing nitrobenzene 0-84-1-7 per cent, soft soap 1-7-3-4 

 per ceat, amyl alcohol 2-6-5'l per cent. 



Agrotis Segetum (grey-worm). — Papasogli recommends to water 

 beets with an emulsion of 5 lb. of nitrobenzene, 5 lb. of sulphuric acid, 

 in 9 gallons of water, to kill the grey-worm, the caterpillar of this 

 noctua. 



Conchijlis amhignella, Hubn. (cochylis of the vine). — The caterpillar 

 (353) 23 



