Proteid

When strong nitric acid is added to an aqueous solution of any of the proteids, a white precipitate forms, which turns yellow on heating the liquid.

1914, Eugene Christian, Encyclopedia of Diet: A Treatise on the Food Question, Digital Edition, unnumbered page, The proteid substances in the body must be formed from proteids taken in the form of food, because only proteid foods contain the element nitrogen.

1996, Arnold Eiloart (translator and editor), M. Bircher-Benner, Food Science for All and a New Sunlight Theory of Nutrition, page 12, As he believed moreover that proteids provide not only the building-material of living substance, but also muscular power, he regarded it as a nourishing principle.