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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$30 OxyncM, ().„ ... ... ... ... 20-01 Nitroi^cn, ... ... ... TT-OO Carbon Itio.xide, CO.„ ... ... 0-04 j\(liR‘ous \aj)oui-, H.jlJ, .. ... 1'40 Nit rif Acid, 11X^O^, ... ... ... j Aininonia, X’H.,, ... ... ... Traces. Hydrides of Carbon, .. ... ... | In f bulpiniretted llydro^'en, fSHj, ... I towns. I Sulpliur Dio.xide, S( b, ... ... j ” Air, fi-eed from moisture and carbon dioxide, contains tlie following percentagi'S of nitrogen and oxygen: — liy Me.isure. B.v Weight. X'itrogen, ... ... TSM!) 70-9!) Oxygen, ... ... 20-Sl 23-01 100-00 100-00 In addition to the bodies aln-ady mentioned, air in most localities contains .germs of miscroscopic (jrganisms. 64. Ammonia, NHg.—Traces of this .gas, either in the free state or as salts, are found both in air and in water. Its great natural source is the decomposition of animal and vegetable substances which contain nitrogen as a constituent. In this way, ammonia is continually bein.g formed in nature by the decay of refuse nitrogenous matter, such as the urine and excreta of animals, and other Itodies. INIany nitrogenous vegetable and animal substances also evolve ammonia on being stron.gl}' heated : among these is coal, which thus forms tlu' iirincipal source from which ammonia is now derived. Ammonia is a colourless gas, with a most pun.gent and charactei-istic odour: in the concentrated state the gas acts as an irritant poison, ))ut when diluted with air possesses a smell rather pleasant than othei-wise. Ammonia does not su})port combustion, and at ordinai-y temperatures does not burn in air. The gas is very soluble in wati'r ; the .solution has the odour of tlu: gas, and constitutes what is commonly known as “ liciuid ammonia.” Ammonia acts as a IKJwerful alkali, neutralising the strongest acids, and n'storing the blue colour to n-ddened litmus. 65. Ammonium Salts.—6n the addition of an acid, such as either sulphuric or hydrochloric, to ammonia, tlu* odoui- disa]ipeai-s, and the acid, as above* stat(*d, is found to be completely neutralised. The reaction may be exju’essed thus :- - Xlb, + IICI lly(li'()( liloi ic. Nil,Cl. Amniiiiiiiiin ('hloride. Nil. Aiuinoiiia. ii^w, Siiliihuric (Nil,),SO,. ..\miii()iiiuiu .-'ulidiate. f)n comjearing, in each case, the formula of tlu* resulting comjiound w-ith that of the acid, it will be* seen that the gi-oup Xll, re-jilaces tlu* hydroge-n of the acid. 'J'his comjiound, Nil,, cannot ('xist in the free* state, but occui-s in a number of chemic-al compounds, and can bi- trans- fei-red from one to another without undergoing decomposition. It is$