Ferric citrate . . . . . . | | 0.100 | | | | 2.00
Mg citrate . . . . . . . . | | | | | | 7.00
CaCl_2 . . . . . . . . . . | | 0.386 | | 0.2569| |
CaSO_4:2H_2O . . . . . . . | | 0.381 | 0.578 | | |
Fe acetate . . . . . . . . | | | | | 0.100 |
___________________________|_______|_______|_______|_______|_______|______

These diets fall as shown, into two classes. The first group correspond to
those of Osborne and Mendel and are available for general testing of any
unknown. The cereal combinations are so constituted that all deficiencies
of salts are covered and the proportions of the cereal are so selected as
to provide the right proportions of protein, fat and carbohydrate. By
adding enough butter fat to supply the "A" the deficiency in the "B" can
be tested and by adjusting the amounts of "B" on the dextrin the cereal
deficiency in this vitamine can be obtained. It is obvious that by
substituting lard for the butter fat one could use the same mixture
properly supplemented with the "B" to determine the "A" deficiencies of
the wheat.

The most prominent worker in the field of the "A" vitamine measurement in
America is Steenbock. His basal diets are a combination of those already
described.

_Steenbock's basal diets_
per cent
Casein (washed with water containing acetic acid) . . . . . 18.0
Dextrin . . . . . . . . . . . . . . . . . . . . . . . . . . 73.3
Ether extracted wheat embryo as source of vitamine "B" . . . 3.0
Salt mixture (McCollum, no. 185) . . . . . . . . . . . . . . 3.7
Agar . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.0