The usual gravity cream sold has from sixteen to twenty per cent fat. The cream removed from the upper part (one-fifth) of a bottle of milk has about sixteen per cent fat. The usual centrifugal cream has eighteen to twenty per cent fat. The heavy centrifugal cream has thirty-five to forty per cent fat. The digestibility of cream depends much upon circumstances. Many serious disturbances of digestion are caused by cream. It is convenient in calculation to make up twenty ounces of food at a time. The first step is to obtain the seven per cent milk, then to take the number of ounces that are called for in the formula desired. One should not make the mistake of taking from the top of the bottle only the number of ounces needed in the formula, as this may be quite a different per cent of cream and give quite a different result. There will be required in addition, one ounce of milk sugar and one ounce of lime water in each twenty ounces. The rest of the food will be made up of boiled water. These formulas written out would be as follows: FORMULA FROM SEVEN PER CENT MILK I II III IV V VI VII VIII IX Oz. Oz. Oz. Oz. Oz. Oz. Oz. Oz. Oz. 7 per cent milk 2 3 4 5 6 7 8 9 10 Milk sugar 1 1 1 1 1 3/4 3/4 3/4 3/4 Lime water 1 1 1 1 1 1 1 1 1 Boiled water 17 16 15 14 13 12 11 10 9 --- --- --- --- --- --- --- --- --- 20 20 20 20 20 20 20 20 20 The approximate composition of these formulas expressed in percentages are as follows: Formula Fat Sugar Proteins I 0.70 5.00 0.35 II 1.00 6.00 0.50 III 1.40 6.00 0.70 IV 1.75 6.00 0.87 V 2.00 6.00 1.00 VI 2.40 6.00 1.20 VII 2.80 6.00 1.40 VIII 3.10 6.00 1.55 IX 3.50 6.00 1.75 It is necessary to make the food weak at first because the infant's stomach is intended to digest breast milk, not cow's milk; but if we begin with a very weak cow's milk the stomach can be gradually trained to digest it. If we began with a strong milk the digestion might be seriously upset. Usually we begin with number one on the second day; number two on the fourth day; number three at seven to ten days; but after that make the increase more slowly. A large infant with a strong digestion will bear a rather rapid increase and may be able to take number five by the time it is three or four weeks old. A child with a feeble digestion must go much slower and may not reach number five before it is three or four months old.