How do I prepare the next composition?

Discussion of the prescription:

1. as a cool ointment could be chosen between the cooling ointment of the PBV or a cool ointment stabilized with borax (see USP). The latter does not qualify here because a reaction between phenol and borax with the formation of naphenolate is inevitable. This salt formation will lose the antiseptic effect of phenol.
2. phenol and urea are water-soluble constituents, which will dissolve in the internal water phase of the cooling ointment.
3. ZnO is insoluble both in the water and in the fat phase and should therefore be rubbed off with the cooling ointment. But because of the predominantly hydrophilic nature of the ZnO, water could be taken from the cool ointment, which therefore breaks. But the practice shows that this problem is not so acute for this composition. Possibly light heating and good stirring of the cooling ointment restores the emulsion. Naturally, a reaction between phenol and ZnO in this system is inevitable.

Preparation

1. prepare cool Ointment According to the instructions of the OJ V;
2. sieve ZnO;
3. rub the urea finely into a mortar and mix with the ZnO;
4. rub this mixture with the castor oil and add the phenol;
5. in all this, mix the amount of cooling ointment until a homogeneous mixture is obtained. If the emulsion discerner preheat lightly and stir until homogeneous.