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.

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$1)0 propaivd by artificial means, it must be cleai’ly undei'stood that no chemical processes have as yet been found capable of producing' an organised structure; further, all (‘vidence hitlieito <)l)taiued, so far as it goes, tends to prove tlii' impossibility of sucli structures beiiig formed otlu'r than througli living agencies. For instance, stai'ch is found, when viewed under the microscope', to have a structui'al organisation peculiar to itself. Starcli may be dissolved, and afte'r sucli solution again obtained in the solid state ; but tlie solid thus produced shows no traces of tlu* original structure of the grains of starch ; neither is there' known any artificial preicess by which the starch may again be' built up inte) structures of the same kinel as tlmse in v'hich it eiriginally ejccurred. Similarh', it is impossible to artiliciall}’ jiroeluce a bleieiel corjaiscle. The •same law ajiplies to minute eirganisms as yeast, bucteria, ctre-. ; none of these can be generateel otherwise than through the agenc}' eif previously e.xisting living be'ings of the same type. So far as any problem can be proveel scientifically, this fact of the impossibility of spontaneous generation is abundantly demonstrated ; experimental evidence of a most conclusive character has shown as certainly as scientific research can, in any case, possibly .show, that living organisms can only be formed by means of similar pre-existing oi'ganisms. ]\Ian may make' a steam engine or a watch, but a yeast cell is beyond his jiower. 84. Composition of Organic Bodies.—Organic comiiounds, generally, have a much more complicated chemical composition than have inorganic comjiounds ; they are mostly, however, n'stricted to comparatively few elements. All organic bodies contain carbon ; many are composed of carbon and hydrogen only, a greater number consist of carbon, hydrogen, and oxygen ; while others contain the four elements, cai'bon, hydrogen, o.xygen, and nitrogen. The majority of organic com- pfiunds belong to one or other of these series. Carbon, more than an}' other element, is ri'inarkalile for the projierty of, in compounds, com¬ bining directly with itself, and so forming most complicatc'd bodies out of comparatively few elements. 85. Classification of Organic Compounds. —Tlu' number of these is so bewildering that, without some classification, it would 1k' impossible to grasp theii' relationship to I'ach otlu'r : recent chemical science has succec'ded in very clearly demonstrating the .constitution of a vast number of these bodies. There ari', in the first place, large numbers of wi'll di'lined compound radicals, consisting of carbon and hydrogen : it has been found possible to group these into distinct fami¬ lies, th(* members of each of which may b(' represented by a common formula. 86. Organic Radicals.—The most imiiortant seric'S of tlu'Si' is that known as the “ IMethyl,” or “ hlthyl ” sc'ries ; these ha\'e the com¬ mon formula (t’,J 1.^,,.^,),^. 'I'liis formula signifies that in the tii'st jilaci* the molecule consists of two si'ini-molecules that ari^ similar in comjiosi- tion , secondly, that in each semi-molecule the numlx'r of atoms of hydrogi'ii is oiu' more than double tlu' number of atoms of carixm. J hc' following is a list of a few of the radicals of this series :$