3. To introduce an equation by the use of which it becomes unnecessary to remember any formulas, as they can all be easily and correctly worked out. The only thing necessary is to remember how to get the six different "cream strengths" to be used in the modifications.

4. By finding the average fat percentage in the milk and cream used in any home mixture, and then using that average in my equation, you can know practically what the infant has been taking.

Starting with a new-born infant to feed, we begin by diluting a "10 per cent. cream" because it contains three times as much fat as proteids, which is about the proportion which exists in a good sample of woman's milk, and taking a "20-ounce mixture" as a basis, because some of you may be used to calculating on that amount, and taking no account of the "sugar of milk" and "lime water" for the present, we would get the following formulas:

1 oz 10% cream + 19 oz. boiled water=0.50% fat-0.17% proteids.

Up to this point the results are identical with those of the present method, as given by Holt, so far as the fat is concerned.

By noticing the proteid column you will see that the proteids take care of themselves, as I have already shown that all "milk-cream mixtures" up to and including 20 per cent. contain practically the same proteid per cent., so that as the cream is added ounce by ounce the resulting proteid per cent. in the mixture must be gradually and steadily raised.

Having reached 3.50 per cent. fat in the mixture obtained by diluting 10 per cent. milk, if, instead of jumping to a 7 per cent. milk as is done in the present method, we take a middle ground and use an 8 per cent. milk, we would get only a very slight reduction in fat, 3.26 per cent., instead of 2.50 per cent., as would have resulted had we used a 7 per cent. milk.

Gradually increase the quantity of this 8 per cent. milk used in the mixture, diminishing the water by an equal amount, until the fat in the mixture is raised to 4 per cent., which is as high as any infant can digest long without disturbance.

Thus

8 oz. 8% cream + 12 oz. boiled water=3.26% fat-1.40% proteids. 9 oz.

་་

+ 11 oz.
+10 oz.

66

66

66

=3.60% -1.57%

The fat having reached 4 per cent., we now change to a 7 per cent. milk to dilute.

Thus

11 oz. 7% cream + 9 oz. boiled water=3.85% fat-1.92% proteids. 12 oz. =4.20% -2.10%

+ 8 oz.

The fat having reached 4 per cent. again, we change to a 6 per cent. milk to dilute.

Thus

13 oz. 6% cream + 7 oz. boiled water=3.90% fat-2.27% proteid s. 14 oz.

The fat again reaching 4 per cent., change to a 5 per cent. milk to dilute.

Thus

15 oz. 5% cream + 5 oz. boiled water=3.75% fat-2.62% proteids.

Changing to 4 per cent. milk or whole milk to dilute: 18 oz. 4% milk (whole)+2 oz. bɔil'd wat'r=3.60% fat-3.15% proteids

The present method as advocated by Dr. Holt, works all formulas on the basis of "20-ounce mixtures," and in order to get more than 20 ounces of food, this method takes fractional portions of 20.

Thus 25 ounces is equal to 20 ounces plus 5 ounces, or 4 more, so 4 more of each ingredient is added; or in 30ounce mixture 1⁄2 more of each ingredient; 35-ounce mixture 34 more, and 40-ounce mixture twice as much of each ingredient, etc.

This requires considerable figuring, and besides there is a different rule for working each set of formulas, thus: one for the 10 per cent. set and one for the 7 per cent. set, while none is given for the 4 per cent. or whole milk set.

If these formulas are to be used in every-day practice in feeding infants, it requires either a considerable taxation of the memory, or constantly going to the text-book every time a new formula is needed.

In order to avoid this, I have worked out the following equation:

The given cream %: cream % wanted the total number of ounces : number ounces to be added.

In this equation you can always know three of the items and it is an easy matter to find out the remaining item.

This equation works equally as well, no matter what per cent. milk is used to dilute or what the size of the mixture desired for the twenty-four hours food.

By applying the equation you can readily see how easy it is to get any of the above formulas.

Thus: If we are using a "10 per cent. cream" to dilute and want a "20-ounce mixture" containing 3 per cent. fat, the question would be how many ounces of the 10 per cent. cream to put in the 20 ounces to get a combination containing 3 per cent. fat.

Applying the formula :

10 (%) 3 (%):: 20 (oz.): x (oz)

10 x = 60

X = 6 oz. of 10% cream in 20 oz. mixture equals 3% fat.

7 (%) 3 (%):: 35 (oz.): x (oz.)

:

7 x = 105

x =

= 15 oz. of 7% cream in 35 oz. mixture averages 3% fat.

Or to work the other way:

Being called to see a child fed on a "home combination" which caused vomiting and undigested stools in a well nourished child, we found it was on a combination like this:

Baby four months old, taking 6 ounces at a feeding made as follows:

2 oz. gravity cream 16%

2 oz. whole milk 4%

2 oz. boiled water

6 oz.

Averaging up the percentages of fat in the cream and milk used, we find that really a 10 per cent. cream is being used to dilute.

Applying the equation we have

10%: x%::6:4

6 x = 40

X = 6%% fat in the combination.

This would disagree on account of the fat, 623 per cent. being entirely too high for any infant to digest at any age, and causing the vomiting, and also the proteids, 2 per cent. being too high at four months. Both the proteids and fat being responsible for the curds in the stools. Another example:

Baby nine to ten months old, 8 ounce feedings:

1 oz. gravity cream at 16%

5 oz. skimmed milk at 1%
2 oz. boiled water

8 oz.

Averaging up the fat percentage in the cream and milk,

we have a 32 per cent. milk to dilute. Applying the formula we have:

X = 25%% fat in the combination.

While this combination in a nine- or ten-months-old baby would be digested with ease, still the baby would be cross and fretful and would either fail to gain weight or would actually lose weight.

Examples could be multiplied indefinitely and are similar to cases actually met in practice.

Thus if any gross error has been made in the feeding, it is easy to correct it by knowing where the fault lies.

Up to this point I have only considered the fat and proteids in the modification of milk. Of course, when the milk is diluted the percentage of sugar, which represents the carbohydrates in an infant's food, is reduced entirely too low, so it becomes necessary to add 5 per cent. sugar of milk to the combination.

This, together with the "sugar of milk" in the milk used, brings the resulting percentage of sugar in the modified mixture up to the required 51⁄2 per cent. to 61⁄2 per cent. or 72 per cent. This holds good until about one-half of the total mixture is some form of milk, then gradually reduce the amount of sugar added.

Thus as the proportion of milk in the mixture grows larger, add a smaller percentage of sugar, as 4 per cent., 3 per cent., 2 per cent., I per cent., and none at all when the child is able to take whole milk.

As cow's milk is acid, while woman's milk is alkaline, it becomes necessary to add something to change the reaction. The best thing is to add 5 per cent. lime-water,