The invention relates to a variable transformer comprising at least one primary winding and at least one secondary winding which can be rotated in relation thereto. The composition comprises a polyoxyalkylene polyol phosphate ester and a polymerizable or reactive functional group-containing compound. The invention also relates to a process for preparing crystalline amoxicillin trihydrate powder, said process comprising: crystallizing amoxicillin trihydrate from a solution containing dissolved amoxicillin; separating the crystals from said solution; and drying the separated crystals, resulting in crystalline powder having a bulk density higher than 0.