Since a small amount of urine-soil added to sodium hypochlorite solution consumes a proportional amount of available chlorine, the amount of urine-soil remaining in washed cloths was determined by measuring the consumption in the solution in which they were dipped.
Cloths soiled with 3-4 month-old sucklings' urine (S), more-than-6 month-old babies' urine (B), adults' urine (A), and urea solution (U) were washed by water in a tub located in a water-bath incubator at 120 shakes/min. 30°C.
RESULTS: 1. (S) and (U) can be easily removed by 3-minute washing repeated twice. 2. After three repetitions of 3-minute washing, as well as after LAS solution washing followed by rinsing by water twice, soil of (A) still remains. (B) also shows similar tendency. 3. After five-minute shaking or three cycles of washing, little further removal was noticed. 4. The shorter the lapse after soiling until washing, the smaller is the soil remained. But, after five hours to twenty-four hours' lapse, the amount of remainder does not change.

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This paper is to investigate the relation between the soap concentration of bulk wash liquid (sodium oleate solution) and the detergency of foam washing. By the use of a C type of foam washing machine of our own make, the effects of the concentration on the foaming property and the relations between the concentration in foam and in residual liquid were studied. Furthermore, the detergency of foam washing and that of immersion washing were compared by the use of natural dirt on the collar and artificial cluster dirt. Following results were obtained.
1) It was found that both a mass of stable foam and high detergency were obtained in the concentration of bulk liquid as high as 0.3%. But foamability was lowered, foam film formed was thin, and the detergency decreased in the concentration of less than 0.3%, though the concentration in foam is greater than that of bulk liquid by foam fractionation action.
2) In the case of the bulk soap solution containing 0.1% of sodium methasilicate, good foamability and the relatively high detergency were obtained in the soap concentration ranging from 0.05 to 0.2%.

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The pressures of foams in a leading pipe of the foam washing apparatus (inner foam pressure) were measured with changing the opening of mesh screen and air flow rate, and the mechanism of foaming action at the opening of mesh screen in the vertical fixed type of foam washing was predicted. Moreover, the effect of foaming action on the detergency of palmitic acid adhered on the mesh screen was studied, and following results were obtained.
1) The inner foam pressure is divided into two elements, one of which is capillary pressure P₁ required to the foaming action, and the other is P2 proportional to the air flow rate.
2) P₁ suggested that the foaming action occurred when the contact angle of foam film to the face of mesh screen grew to 30°. This P₁ is correlative to the force of bubbling sorption involved in a unit foaming action, and P₂ to the frequency of that action.
3) With decreasing the opening of mesh screen, or with increasing the air flow rate, the inner foam pressure increased and the detergency also increased. Accordingly, we can realize that the foaming action from inner part of substrate increased the detergency.

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