SCIENCE AND INDUSTRY. 
gently all the time. Too much acid produces a fine-grained curd, which. 
is difficult to drain and handle. The whey is next run off, and the curd 
washed well in cold water; then drained and pressed. If a tough, 
hard curd is required, it is covered with water and heated to 175° F. 
In the lactic and sulphuric process, the skim milk is heated to 98° 
F’., and 10 per cent. of starter is added. In about six hours, the acidity 
will reach -75, and the milk coagulates. The curd is cut, and steam 
heated to 120° F., and the whey is then run off. The curd is washed in 
boiling water and drained. It is next dissolved in a washing soda 
- solution, using 3 Ibs. of soda to each 100 gallons of milk, and an amount 
of water equal to one-third of the volume of milk. The mixture is 
then heated to 140° to 150° F., and the curd dissolves. The tempera- 
ture is reduced a little, and the casein is precipitated by H,SO, used 
as in the sulphuric method. The curd is thoroughly washed ,in water, 
drained, and pressed. 
Edible Casein —This is made to provide an edible casein for the 
manufacture of the numerous patent foods. Sweet skimmed milk is 
heated to 85° F., and hydrochloric acid at the rate of 1 oz. to each 
gallon of milk is used, diluting it with two and a half. times as much 
water. After running off the whey, the curd is washed at 110° F., 
and again at 140° F., and then in boiling water. After draining and 
pressing, it should be light-yellow in colour, and free from taste and 
smell. The moisture content should not be more than 12 per cent., and 
the casein, when ground and mixed with 14 per cent. by weight of 
_ anhydrous sodium carbonate, should be readily dissolved in water. 
To render curd fat free and white in colour, the precipitated curd, 
after well washing and pressing, is sometimes stirred to a pulp with half 
its weight of water, and then steamed for 25 to 30 minutes in a wooden — 
vat, with about one and a half times its weight of a1 per cent. solu- 
tion of soda. This removes the lactic acid and butter-fat. After 
heating, the mass forms a thin milky fluid, which is transferred to a 
separate vessel to cool, and precipitated with nitric acid. One hundred 
parts of curd yield 40 parts of purified casein. 
Whatever process is used in manufacturing, the casein should be 
dried in an oven with carefully regulated temperature (120° to 140° F.). 
The cost of manufacture will vary very much when full account is 
taken of all costs (wages, fuel, depreciation, raw material, acids, rennet, 
packing, &c.). At the present time, these are continually changing, so 
that any estimate made may not be reliable for long. Best French 
‘casein was selling at £110 a ton nine months ago. Technical casein 
is now selling at £80 to £83 a ton; and casein for making paints, at 
£75 to £80 a ton. Only the best quality will find a good market, as 
large stocks are held in England and the United States of America; 
and France, even with her depleted herds, is able to supply most require- 
ments. It is expected, however, that there will be an increasing demand, 
and Australia is finding a market in the East. The world’s'demand for 
casein at present is 20,000,000 Ibs. annually; and in 1918, United States 
of America produced nearly 9,000,000 Ibs. — In 1910, United States of 
America imported 3,800,000 Ibs. In 1917, New Zealand exported. 
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