What is Imperial Granum?  Granum is Latin for seed.  In modern medical jargon it is a “stack of thylakoids in the chloroplast, containing the light harvesting system and the enzymes responsible for the light dependent reactions of photosynthesis”. A diluent is a substance used to dilute or cut another substance.  In the case of Imperial Granum (I don’t know where the Imperial comes from), it is basically a wheat and milk gruel and the insert recommends it for nursing mothers, babies and invalids. For babies, it is first dissolved in their formula (if they are not nursing) and after the child is six months old, it is fed as a cereal.  Nursing moms are to take it three times a day, 3 tablespoons cooked in a cup of water and a cup of milk.  She can add cocoa or some other flavouring, if she likes.  The box says: “This original and world renowned dietetic preparation is a substance of unrivaled purity and nutritive worth derived by a new process from very superior growth of wheat—nothing more.”  The box also says that it is the invention of an eminent French chemist although gruel of various grains has been known and used for centuries.  The Greeks had it, the Maya and the Aztecs and they certainly used it in Medieval Europe.

I tried to find out something about the company that sold it with indifferent success.  It was made by John Carle & Sons, Inc. from New York City.  This company was established in 1817.  Imperial Granum was manufactured in New Haven Connecticut and registered June 5, 1877.  It was still going strong in 1915 when L. E. La Fétra, M.D. a visiting physician to the children’s ward at Bellevue Hospital in New York, wrote a paper on it’s value in treating premature infants.  Both Robert Benchley and Mark Twain mentioned in their writing as if it were common in households.

I did find that trading cards and advertising for Imperial Granum are considered collectibles and are selling on eBay. I also discovered that there is a well-known heritage building in New Haven, the Imperial Granum-Joseph Parker Building(s).  They are joined by a ‘party wall’ and are believed to have been designed by the architectural firm of Henry Austin.  The Imperial Granum Building has the city’s only cast-iron façade. [http://www.flickr.com/photos/nationalregister/3671988387/in/photostream/]

Just on spec, I checked out “Pablum” which is the gruel that I am familiar with.

According to Wikipedia, Pablum Mixed Cereal was made from a mixture of ground and precooked wheat (farina), oatmeal, yellow corn meal, bone meal, dried brewer's yeast, and powdered alfalfa leaf, fortified with reduced iron — providing an assortment of minerals and vitamins A, B₁, B₂, D, and E. Pablum was developed by Canadian pediatricians Frederick Tisdall, Theodore Drake, and Alan Brown,[1] in collaboration with nutrition laboratory technician Ruth Herbert (all of the Hospital for Sick Children in Toronto), along with Mead Johnson chemist Harry H. Engel.[2] The cereal marked a breakthrough in nutritional science: it helped prevent rickets, a crippling childhood disease, by ensuring that children had sufficient vitamin D in their diet.

Apparently there are cultures and cuisines that prize some form of gruel as a delicacy. In Korea, they have Jat-juk, or Pine Nut Gruel -- finely ground rice swimming with pine nuts to make a nutritious (protein, iron and vitamin B) and delicious soup.