Lactobutyrometer

It is placed in a water bath at 40°. After 20-30 minutes, a clear solution of fat in ether collects on the surface of the liquid in the apparatus. The height of the column of risen fat is read on the L. scale, and using the Marchand table, the percentage of fat in the milk is determined. - L. G e r b e r's (fig. 2) consists of a tube narrowed in the upper part and widened in the lower; the top of the tube is sealed, while the bottom is closed with a rubber stopper. For milk analysis, 10 cm³ of ether, 10 cm³ of 93-95° alcohol, 3 drops of Kenville's alkaline solution (Ques-neville) [32 cm³ of a solution of caustic soda sp. gr. 1.34 (31.22% solution) and 225 cm³ of ammonia sp. gr. 0.93 (18.64% solution)] and 10 cm³ of the milk being tested are poured into the apparatus. All liquids must be at 15°. The apparatus is sealed with a rubber stopper, the mixture is thoroughly shaken, placed for 5-10 min. in a water bath at 40°, and then the height of the separated fat layer is read on the apparatus scale. In the Tollens and Schmidt table, the percentage of fat in the milk corresponding to the height of the column of the separated fat layer is found. The Gerber apparatus has the advantage over the Marchan apparatus that it allows for more thorough shaking of the liquid and more accurate reading of the separated fat layer.

The determination of fat in milk by means of the L. is a less accurate method than the Soxhlet's weight extraction method and the method of determination by means of the butyrometer (see) Gerber; nevertheless, for many practical purposes, e.g. in the control of milk reception in hospitals, sanatoriums, public canteens, etc., it is quite acceptable and deserves attention for its simplicity and sufficient reliability of the results obtained. In terms of accuracy, it significantly surpasses the optical method of Fezer (see Lactoscope).