The more important of those in use to-day are carbolic acid, the perchloride and biniodide of mercury, iodoform, formalin, salicylic acid, &c. Carbolic acid is germicidal in strong solution, inhibitory in weaker ones.
Similar spots are produced on potatoes in America by the fungus Oospora scabies, and in both cases, if affected "seed" potatoes are steeped in a solution of 2 pint formalin in 15 gallons of water for two hours before planting, the attack on the resulting crop is materially lessened.
It is also advisable to wash all woodwork and gangways annually with a weak solution of formalin, or other inodorous germicide.
When exposed to air the latex gradually undergoes putrefactive changes accompanied by coagulation of the caoutchouc. The addition of a small quantity of ammonia or of formalin to some latices usually has the effect of preserving them for a considerable time.