[Illustration: _Details of an American Apparatus for Preparing Soured Milk_ FIG. 57 The figures give diagrams A, B, C, and D of an apparatus useful for the preparation of lactic foods. The incubating can A, is made of block tin, and is intended to contain the milk. B, the warm water container, should be a stout walled vessel with a circular aperture in the lid, through which the incubating can may be passed, and clamped down as in C. B is fitted with three stout iron legs, which should be sufficiently long to allow of a small lamp or gas-jet being placed beneath the container to maintain a uniform temperature. D gives an external view of the apparatus. For the preparation of soured milk, separated milk is placed in the incubating can, and heated up to 100° C. (212° F.) for thirty minutes. It is then allowed to cool to room temperature, and the culture, or tablet containing the lactic acid bacteria, is then added, and thoroughly stirred for a minute or so. The can is then immersed in the warm water container and kept at a temperature of 86° F. to 104° F., according to the organisms used, for ten to twelve hours. By the end of this time the milk ought to be converted to a jelly-like mass, and after being stirred vigorously for a short time, may be cooled on ice, and is then ready for consumption.] The incubating temperature could very conveniently be maintained by an electric radiator, and as the insulation would largely prevent leakage, the amount of electric current used would not be large. The regulating apparatus might consist of a thermometer with platinum wires fused through the stem at the proper temperature, say 100° F. When the mercury rises to this figure it will complete the circuit of a battery which will actuate certain well-known devices for turning off the current which actuates the radiator. In this way a very fine automatic arrangement would be achieved. Steam pipes might be used instead of the radiator, and the thermometer above described could be used in this case also, with appliances to cut off the steam. On the large scale, labour-saving appliances, such as the mechanical brush jar and bottle washer, and the automatic filler for jars or bottles, would be employed, and an overhead trackway for carrying the trays of jars from the steriliser to the incubator would be a great convenience. A further adjunct of considerable importance would be a cold room, worked either by ice or a refrigerating machine, in which the jars could be stored after incubation, so as to arrest the process of lactification, and maintain the soured milk in good condition until required for use. CHAPTER VIII SOURED MILK IN HEALTH AND DISEASE