Summary and Conclusions
Price’s procedure as slightly modified (4) was used for studying the germicidal action of cleaning agents on the hands and showed that rosin soap and a commercial soap containing rosin were more active germicidally on the bacteria normally found on human skin than the usual commercial fatty acid soaps free from rosin soap.
The experiments indicate that the lather of a 10‐percent coconut oil soap solution and of a 10‐percent coconut oil‐rosin soap solution are germicidally active against the organisms removed. However, three 2‐minute washes with these soap solutions had little effect on the bacteria not removed from the hands. The use of a 10‐percent rosin soap solution in the same manner had a marked germicidal effect against both the organisms removed and those remaining.
The lather of a commercial soap containing rosin soap was shown to be germicidally active, but three 2‐minute washes had only a slight effect on the resident flora. However, the regular use of this soap daily for one week led to substantial reduction of both the transient and resident flora of the hands.
The evidence of germicidal activity of rosin soaps and soaps containing rosin, both with regard to these hand‐washing experiments and the “in vitro” (7) experiments, indicates that wider consideration might well be given this type of soap where germicidal activity is of importance.