Citric acid: H_2O . . . 111.1
Fe citrate: 1.5H_2O . . 6.34
KI . . . . . . . . . . 0.020
MnSO_4 . . . . . . . . 0.079
NaF . . . . . . . . . . 0.248
K_2Al_2(SO_4)_2 . . . . 0.0245

[N.B.--The ingredients of the artificial protein-free milk are mixed as
follows: Making proper allowance for the water in the chemicals the acids
are first mixed and the carbonates and citrates added. The traces of KI,
MnSO_4, NaF, and K_2Al_2(SO_4)_4 are then added as solutions of known
concentration. The mixture is then evaporated to dryness in a current of
air at 90 to 100 Centigrade and the residue ground to a fine powder.]

_e_. When brewers' yeast is used as a source of the "B" vitamine it
is first dried over night in an oven at 110 C. and then subjected to the
same purification process as the casein and the starch to remove all
trace of the "A."

The reasons for the special precautions just described have arisen from
some recent work of Daniels and Loughlin who claim that commercial lard
contains enough "A" vitamine to permit rats to grow, reproduce and rear
young. The British authorities explain their results as not due to the
presence of the "A" vitamine in the lard but to a reserve store in the
bodies of the animals. They hold that animals may thus store the "A"
vitamine but that apparently they have no storage powers for the "B" that
are comparable to it. Osborne and Mendel repeated the experiments
described by Daniels and Loughlin, using the purification methods just
described, but failed to obtain similar results with either commercial
lard or with the purified fraction. They question the validity of the