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ART. L1V.—RESKARCHKS ON MM. VARRENTRAPP AND W1LŁ*8 METHOD OF ANALYS1S. By M. Reizet.

M. Reizet has given an attentive ezaminalion to the new process recommended by MM. Varrentrapp and Will, for the determination of Nitrogen in the analysia of organie sub-stances. This process* is founded on the generał law, that organie substaoces are decomposed under the influence of the fized alkalies, into water, and carbonie acid, and, when nitrogen is present, ammonia. It results from the ezperiroents of M. Reizet, that this process is not free from sources of error. In the flrst place, the mizture of limę and soda retains a por-tion of atmospheric air in a peculiar State of condensation; this air cannot be separated either by a current of gas or by the influence of a vacuum. During combustion the nitrogen of this air gives rise to ammonia, and consequently inereases the resulting amounls of this compound. Faraday has some time sińce remarked that, organie bodies, not containing nitrogen, carbon itself, and those metals which decompose water, yield ammonia, when calcined in contact with air and potassa.

Another source of eiror is, that the alcohol in which the perchloride of platinum is dissolved, reduces this salt into in-soluble protochloride ; this reduction takes place slowly— nevertheless there is sufficient of the protochloride formed to inereasethe weight of the aminoniacal salt of platinum, and consequently augment sensibly the estimation of the nitrogen. It is inexplicable how MM. Varrentrapp and Will have al-ways obtained less nitrogen than theory would indicate in the objects of their analysis, sińce the cause of error would tend to give an ezcess, unless it be admitted that, during the pro-

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