The so-called 90 _benzol_—a commercial benzol of which 90 per cent. distils at 100° C.—has naturally a somewhat weaker action, although, in respect of the poisoning symptoms produced, it is similar to that of pure benzene. _Pure toluene_ (boiling-point 111° C.) and purified toluol (commercial product, boiling-point 109°-112° C.) produce, when inhaled, gradually increasing narcosis in the three kinds of animals referred to; they produce no symptoms of convulsions or spasms. After the animals have been taken out of the bell, recovery is not so rapid as after benzine inhalation, but takes from half an hour to one hour. In rabbits and cats 0·046-0·05 per thousand produces after fifteen minutes staggering and paresis; after thirty minutes deep narcosis. The dog is again somewhat more susceptible, as little as 0·034 per thousand causing these symptoms in the same time. ‘Purified toluol’ (commercial product) acts somewhat less rapidly than pure toluene, but this small difference in effect need hardly be considered. Other poisons were also investigated:— _Solvent naphtha I_, a commercial product, of which 90 per cent. comes over at 160° C.; it contains little toluene, chiefly xylene, pseudocumene, and cumene. _Solvent naphtha II_, of which 90 per cent. comes over at 175° C, it contains besides xylene, chiefly pseudocumene, mesitylene, cumene, &c. The fumes of solvent naphtha I cause, when inhaled by rabbits, dogs, and cats, gradual narcosis, although not nearly so quickly as toluene at similar concentrations; recovery usually takes over an hour after the deeply narcotised animals have been removed from the bell. Rabbits and cats are affected in about equal degree. The dog is the more sensitive. Rabbits and cats can tolerate about 0·012-0·013 per thousand of the fumes of solvent naphtha I in the atmosphere for a long time without any symptoms. Only after breathing for fifty minutes air containing 0·0536 per thousand do they become narcotised. In the dog 0·036 per thousand causes narcosis only after thirty minutes. With the fumes of solvent naphtha II I could not affect rabbits at all. The cat also, in spite of long inhalation of the heavy fumes, showed no marked symptoms of poisoning. In the dog gradual narcosis came about only after an hour’s inhalation of 0·048 per thousand. The fumes of pure _xylene_ caused narcosis in rabbits after forty minutes’ inhalation of 0·05 per thousand in the atmosphere; after being taken out of the bell the animals recovered slowly (after half an hour to one hour). _Cumene_ causes no symptoms after one hour’s inhalation in a concentration of 0·06 to 0·07 per thousand. This explains the effects of solvent naphtha I (in which xylene preponderates) and solvent naphtha II (in which pseudocumene, cumene, &c., preponderate). After effects were not observed.