Lactoscope

LACTOSCOPE, an instrument for determining the amount of fat in milk, based on measuring the degree of transparency of milk. The Feser lactoscope (see illustration) consists of a small cylindrical vessel, in the lower narrowed part of which is inserted a white porcelain rod (a) with black marks. To determine the fat content in milk, 4 cm³ of the milk being tested is poured into the L. using a pipette (B), and water is added to it gradually until the milk is diluted to the point where all the marks on the porcelain rod become clearly visible, and they can be counted without excessive visual strain through the layer of diluted milk in falling light. The more fat contained in the milk, the more water must be added for the marks to become clearly visible. The upper level of the diluted milk indicates on the outer scale of the instrument the percentage of fat content in the milk (numbers on the right) and the amount of water added to it (numbers on the left). The readings of the Feser lactoscope do not have great accuracy, since the opacity of milk depends not only on its fat content, but also on dissolved casein and potassium phosphate salts; furthermore, the results of the examination are influenced by the degree of illumination, the visual acuity of the observer, and the distinctness of the black marks on the porcelain rod of the instrument. In unfavorable cases, by means of

the Feser L., 1.0-1.5% more or less fat may be found in the milk than is actually present. In sanitary practice, the L. is used for rapid market control of milk. When working with a verified instrument and with the researcher's known experience, by means of the L. one can obtain results that are quite satisfactory for practical purposes. For scientific research work, in which greater accuracy of results is required, the Feser lactoscope

is not suitable.

N. Ignatov. Liga.—see lit. to art. Lactobutyrometer.