Definition of "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.

1907, R. Douglas Bailey, The Brewer's Analyst, page 89

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. All proteids contain nitrogen, but all nitrogen does not contain protein. All proteids, therefore, are nitrogenous compounds.

1914, Eugene Christian, Encyclopedia of Diet: A Treatise on the Food Question, Digital Edition, unnumbered page

It was in the forties of the last century that the great chemist, Justus Liebig, brought the chemistry of food up to this point. 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.

1996, Arnold Eiloart (translator and editor), M. Bircher-Benner, Food Science for All and a New Sunlight Theory of Nutrition, page 12