Food : its adulterations, and the methods for their detecton / by Arthur Hill Hassall.

  • Arthur Hill Hassall
Date:
1876
Catalogue details

Licence: Public Domain Mark

Credit: Food : its adulterations, and the methods for their detecton / by Arthur Hill Hassall. Source: Wellcome Collection.

    42/973 page 26
    the amounts of the nitrogenous organic matter found in certain waters especially river waters in summer and winter. Tliese are shown in the analyses of Drs. Franldand and Odling, made for the Royal Com- mission on Water Supply, ] 869, to he very great and remarkable Th.ames below weir, at Staines. Filtered Tliames water at Hampton. May 2nd. Oct. 28th. May 4tli. Oct. 28th. In 100,000 parts or- ganic nitrogen . Ditto carbon . •027 •304 •097 •304 •024 •260 •0.57 •263 . The foUowing causes appear to us to afford some explanation of this sti-ilang difference, and to account for the much larger quantity ol albuminoid organic matter in winter. First, the streams and floods of winter which wash out the dykes and ditches in commimication with the Thames; second, the death and decay of many forms of vegetable and animal life; third, the diminution in the amount of minute and infusorial life in the water ; and, fourth, the slower decom- position and destruction of the organic matter in winter. The presence likewise in considerable amounts of ammonia, nitrous, and nitric acids, derivatives of lu'ea and albuminoid matter, woidd also serve, especially when taken in conjunction with other unfavourable results of analysis, to condemn a water. With respect to nitrous and nitric acids in water much has been said and written, and much dis- cussion has taken place as to their significance and importance in potable waters. PURIFICATION' OF WATER, Impure water, when left for a time, imdergoes two different processes of pm-ification. The one results from the decomjjosition of the organic matters contained in the water, and theii- breaking-up into ammonia, carbonic acid, sidphm-etted hycbogen, &c.; the other is due to the oxidation of that matter, the oxygen being derived from the air continually absorbed by the water. This process of oxidation is, of course, gi-eatly promoted by the motion and agitation of the water, as this brings the oxygen into more intimate contact with the organic matters in solution. * Both these methods, judged by their practical residts, and especially the latter, are highly important; and were it not for them, disease resulting from the drinking of impure water would be of much more frequent occurrence than it now is, and it is only of late years that the importance of the purification of water by oxidation has been at all adequately recognised. But even now the extent and limits of its
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