The cooking is done in copper-jacketed kettles, in glass-lined metal, or in wooden tanks, the tanks being heated with coils. The glass-lined tank has the advantage of very little metal coming in contact with the pulp and can be kept cleaner than wood. A question has been raised regarding the suitability of copper for a cooking utensil, though no positive objection has been made. The vacuum pan is coming into use for concentrating pulp, but has been little used in making the finished ketchup. The jacketed-kettle is used by most manufacturers, though the tank and coil is being adopted by those who wish to make large batches, as it is the more economical. Agitators are no longer used, as by proper handling of the steam and automatic traps, little burning occurs on either kettles or coils. The efficiency of the open tank or kettle is increased by providing a strong exhaust or suction for the air at the back and just above the top of the kettle. A swiftly moving current of air across the top of the kettle will carry off the steam and shorten the time of heating from ten to twenty per cent. A pulp may be reduced in a vacuum pan in about one-fourth the time necessary in the open kettle and with a marked conservation of color and flavor. The vacuum pan may be used for quick reduction and the finish be made in open kettles in order to apply the heat long enough to spice and to sterilize. There are possibilities along these lines which have not been developed. The time of cooking a batch of ketchup will depend upon the equipment and the consistency of the finished product. With a good kettle or coil and ample steam-supply a batch should be completed in from thirty-five to forty-five minutes. This gives sufficient time to get the most desirable flavor from the spices and is not so long as to result in discoloration. SEASONING.