My mom's Watkins cookbook is too fragile to lend itself to browsing through it but I found that there are several copies available on eBay and I got one for $6.00. I was looking through it and started at the back and was reading some recipes with a mixture of fascination and revulsion until I got to the chapter heading for those pages. It was FOOD FOR INVALIDS. The first one that caught my attention was Irish Moss Jelly. I thought Irish Moss was a brand name but it is made with actual moss blended with water, milk and sweetened to taste. I discovered that it's a commercial product that can be purchased for eating or medicinal uses or planted and grown for ground cover. It is also known as Pearl Moss.
Another recipe was for Fermanlactol Milk in which a crushed fermanlactol tablet was added to 12 hour old milk and allowed to stand in a warm place for 12 to 24 hours. I don't think the tablets are made anymore but that lead me to read up on lacto-fermentation which is a centuries old method of preserving fruit and vegetables. Kimchi and sauerkraut are (or are when homemade) made that way and whey can be used instead of salt for preserving fruit. The chapter had a recipe for making whey. There is a recipe for Sherry Eggnog Or Brandy Or Whiskey, for Gruel, Milk Lemonade, Beef Juice, Beef Tea and Albumen Water.