A text-book of the science and art of bread-making : including the chemistry and analytic and practical testing of wheat, flour, and other materials employed in baking / by William Jago.

William Jago

Date:: 1895

Credit: A text-book of the science and art of bread-making : including the chemistry and analytic and practical testing of wheat, flour, and other materials employed in baking / by William Jago. Source: Wellcome Collection.

87/740 page 55

$tlu'ir ccnstitiu'uts. Of tlio ,”;roiit luajority of tli('S(‘ liodios iiotliinj' v(>ry (lotinite is known as to tlioir constitution ; a lai't^c numlicr of them are liasic in tlieir cliaracter, and hence arc known as nitrogenous organic liast's, or “alkaloids.” 112. Substitution, or Compound, Ammonias.- IMany of the nitrogenous organic bodies an' built u})on the same type as ammonia, and may be viewed as ammonia in which one or more of the atoms of hydrogen are replaced by com2)ound radicals. These com})ounds are termed “amines,” or “substitution ammonias.” The three bodies, liroiiylaniine, nu'thylethylamine, and trimethylamine, whose fcjrmuhe are given in a preceding 2)aragra2)h, are examjjles of amines. The methylamines ai’e gases at ordinary tenpieratures, having a strong ammonical and tishdike smell. Trimethylamine is })ro(luced by decom¬ posing jiroteids, and is the source of the characteristic smell of tish. 113. Alkaloids.—This name is aj)j)lie(l to a class of organic bodies, most of which contain nitrogen, carbon, hydrogen, and oxygen. All these bodies are basic, while many ai'e able to neutralise even the strong<‘st acids, as sulj)huric acid. They are, as a class, remarkably energetic in their action on animals ; thus, quinine and moi'idiine are most j)owerful medicines, while strychnine and brucine are among the most violent jKUsons ; but little is understood of the constitution of the alkaloids; it is i)robable tliat the»y ai e of the same type as the comjiound ammonias. For the sake of uniformitx' in chemical nomenclature, it has been i)roj)osed to restrict the termination “ine” to the alkaloids; for this reason, glycerin, dextrin, tire , should never be written glycerine, dextrine, ii:c. 114. Amides and Amido-Acids.—Amides may be viewed as derivatives of acids in which amidogen, NIL, replaces hydro.xyl, HO ; or they may be looked on as ammonia in which one or mort; of the hydrogen atoms are reiilaced by organic radicals. Urea, CON.^H^, is a typical amide. It may be viewed as a derivative of carbonic acid CO(HO).^, in which case the two groups of HO are rejdaced by two gr(.)U])s of NH.^; or on the other hyjiothesis maybe regardeil as two molecules of ammonia, NJf.,, with a pair of hydrogen atoms rejilaced by CO, thus :— (H ^ ^ CO = CON.,!!,. AT ' I'rea, Carlianiiile. ^ ( H The amides ai'e distinguished from tlu^ amines by the latter being incapable of dei'ivation in constitution from an acid. Among alludes found in jilants are asparagine, CjF.^O.,, and glutamine, Cjl 1 i„N._,0^. The amides are crystalliiu', dillusilile bodies. Asparagine is soluble in hot water, but not in alcohol or (‘ther. The amido-acids are bodies intermediate in character betwc'i'ii an acid and a weak base, fullilling under dili’erent circumstances the functions of eitlu'r. They may be viewed as deri\ati\'es from organic iicids in which hydrogen of the acid radical is replacc'd by amidogen.$