1. Experiments to determine the toxic doses of some dipping fluids containing arsenic and sulphur are described.
2. It appears that in all the more common forms of arsenical preparations, which are soluble in water, the m.l.d. for rabbits can be calculated on the basis of approximately 0•014 gm. of As₂0₃ per Kg. of body-weight. Sheep, cattle and horses are more susceptible than rabbits to arsenic.
3. The m.l.d. of diluted (dipping-strength concentration) Capex Lime Sulphur Dip for rabbits is approximately 7.5 c.c. per Kg. of body-weight and for sheep approximately 15 to 20 c.c. per Kg. of body -weight.
4. In dipping-strength concentration Tarzan Lime Sulphur Dip and Nelson's Polysulphide Dip possess approximately the same degree of toxicity as Capex Lime Sulphur Dip.