Literature on the toxicity of esters of acetic acid compares them only on the basis of the atmospheric concentration required to produce muscular incoordination or narcosis. On this basis, methyl acetate is the least hazardous of the first four members of the series -- methyl, ethyl, propyl and butyl acetates. However, this comparison fails to take into account other physiological actions which accompany the effect of the esters on the nervous system. Narcosis may be preceded by, or itself involve, drastic changes in circulation or serious irritation of mucous membranes or the respiratory or gastro-enteric tracts. To obtain information rapidly to decide upon the suitability of methyl acetate, as compared with other acetates, as a component of a mixed solvent, dogs vere expoeod for repeated short periods, to concentrations of methyl, ethyl and butyl acetates, corresponding to half the narcotic concentrations.