The Pamphlet Collection of Sir Robert Stout: Volume 68
[introduction]
Reference has been made to the manufacture of condensed milk During the past winter I received a sample of New Zealand condensed milk, which, although perfectly wholesome and agreeable to the taste, was certainly not marketable in England. It was solid and gelatinous, instead of being creamy and liquid. I examined the sample side by side with a sample of the best brand made by the Anglo-Swiss Company. The difference in appearance was most striking, and I took photographs from the microscope, and subsequently obtained a drawing by a competent artist.
It will be noticed that in the Anglo-Swiss sample the sugar-crystals are small and regular, whereas in the New Zealand sample they are large and irregular in size. I have on several occasions been enabled to see the system of milk-condensing in some of them factories of Switzerland, and in the year 1887 I went to that country to obtain some information for the benefit of a large company which is interested in New Zealand, and which had in contemplation the establishment of a condensed-milk factory in the colony. The following are the details of cost of the apparatus required (Swiss-made) :—
Copper vacuum of 5,000 litres capacity, for heating up to 75lb. per square inch, with vacuum-meter, thermometer, and glass gauge to show the level of milk within, with safety-valve, three stop valves for condensing water, three air-taps for double bottom, one air-tap for the vacuum apparatus, £340; a copper elbow for the top of the vacuum, £16; a shutting-off register for milk, steam, and water, £24; a vacuum of 300mm. diameter of piston with 480mm. stroke, sixty revolutions per minute, for driving by belt, with fast and-loose pulley, and injection-cock, £168; cast-iron condenser with injection-pipe, £23; two copper pans for preliminary heating of the milk, each of 1,500 litres capacity, for heating to 75lb. per square inch, with double-bottom stop-valves for steam and condensed water, a safety-valve, discharge-valve, and three air-taps, £180; two cans page 31 with discharge-tap for filling the tins, £16; the cooling apparatus for forty-seven milk-cans, £160; one hundred cans, £112; copper weighing-pan for reception of the milk, £26; two washing-tables with four lever steam-and water-valves, £48; milk-tin-testing apparatus (4) with air-pump, £76. An engine of twelve-to fifteen-horse power is required for this installation, together with two Cornish boilers, each with 60 square metres of heating-surface. The vacuum-pan of 5,000 litres capacity, the size usually adopted, permits of a daily working of 10,000 to 15,000 litres of milk.
Per Cent. | |
---|---|
Water | 6.50 |
Cane-sugar | 10.00 |
Milk-sugar | 4.00 |
Fat | 3.60 |
Casein | 4.00 |
Ash | 0.50 |
28.60 |
Water | 0.25 |
Cane-sugar | 0.40 |
Ash | 0.02 |
Fat | 0.10 |
Casein | 0.12 |
Milk-sugar | 0.12 |
1.01 |
The soldering-machine costs £15 in London, and I am informed that a smart girl can solder fifteen gross of tins per day. The solder used in the process costs 7½d. per gross of tins. The prices paid for milk at the Aylesbury Condensing Factory were 6½d. for the six summer months, 7½d. for two months, 8½d. for two months, 9½d. for one month, and 10½d. for one month. These prices, I believe, have been recently slightly reduced.