The invention relates to a liquid analyzing apparatus, especially for use in determining the fat content of milk samples. The apparatus comprises manually operated dosage syringes or pumps for mixing diluent and liquid sample in a predetermined relationship, a manually operable homogenizer for providing homogenized mixture to photometric measuring means including a cuvette. The homogenizer and the photometric measuring means are arranged within a temperature controlled block or body made from a heat conductive material. The homogenizer may comprise a piston pump having a piston provided with an O-ring and rigidly connected to a piston rod oscillating angularly in operation.