By an oscillographic method the total arc voltageeis measured as a function of arc currentiat high pressure in a 1500‐volt d.c. circuit in whichi(in the 1–7 ampere range) is independent of changes ine. Thee‐icharacteristics are taken for copper electrodes in nitrogen up to 1275 atmospheres pressure, with the result thateincreases two times atp=100 atmos. and five times forp=1000 atmos. The pressure effect in helium is similar to nitrogen. Attempts to obtain measurements in hydrogen showed a striking instability of the hydrogen arc at high pressure.