14 BULLETIN 1160, U. S. DEPARTMENT OF AGRICULTURE. 
The aliphatic amines and substituted ammonium compounds showed 
considerable toxicity. Tetramethyl ammonium chloride was the most 
toxic, methylamine hydrochloride the least. Of the two cyclic amines, 
benzyl amine was five times as toxic as aniline. 
The aliphatic aldehydes and ketones had a low order of toxicity. 
Benzaldehyde was moderately toxic. 
The aliphatic alcohols showed little toxicity. Benzyl alcohol, a 
cyclic compound, was more toxic. 
Cresol U. S. P. was the most toxic of the phenols, pyrogallol the 
least, while phenol and resorcinol occupied an intermediate position. 
The esters of cyclic compounds showed some toxicity. 
Sulphonic acids and their salts had little effect. Picric acid and 
sodium salicylate showed appreciable toxicity. Fish-oil soap (sodium 
base) was relatively ineffective. 
Benzene, toluene, and xylene were only slightly toxic. 
Aliphatic compounds containing chlorine were but slightly toxic; 
benzene derivatives containing chlorine were much more toxic. 
Essential and fixed oils showed some toxicity. 
Piperidine as the sulphate and trimethylamine as the hydrochloride 
when applied in dilute soap solution were more toxic than the respec- 
tive free bases. Nicotine as the sulphate and nicotine base were of 
approximately equal toxicity. 
Pyridine and itshomologs as found in commercial pyridine, alkaloids, 
sodium phenol sulphonate U. S. P., aliphatic aldehydes and ketones and 
aliphatic alcohols of low molecular weight were relatively nontoxic to 
the nasturtium plant. Most of the other compounds used in this in- 
vestigation had considerable toxicity. 
Neither the volatility nor the boiling point is a reliable index of 
the toxicity of organic compounds when used as contact insecticides. 
Chemical structure does not appear to be a dependable index of 
toxicity. Nevertheless, it is probably the best empirical guide at 
present available for the study of contact insecticides. 
