A treatise on chemistry. Vol. III, The chemistry of the hydrocarbons and their derivatives, or, Organic chemistry. Part I / by H.E. Roscoe & C. Schorlemmer.

  • Henry Enfield Roscoe
Date:
1881
Catalogue details

Licence: Public Domain Mark

Credit: A treatise on chemistry. Vol. III, The chemistry of the hydrocarbons and their derivatives, or, Organic chemistry. Part I / by H.E. Roscoe & C. Schorlemmer. Source: Wellcome Collection.

Provider: This material has been provided by University of Bristol Library. The original may be consulted at University of Bristol Library.

    63/744 (page 45)
    METHOD OF GAY-LUSSAC AND THENARD. of nitrogen. Some of the analyses thus conducted are fairly accurate, when the calculations are corrected, this being neces- sary because at that time neither the true composition of carbon dioxide nor that of water was known. Thus corrected, Gay- Lussac and Thenard's numbers for the percentage composition of sugar are as follows. The results calculated from the formula are added for the sake of comparison. Found. Calculated. Carbon . 41-36 42-10 Hydrogeu . . 0-39 6-44 51-I4 51-46 98-89 100-00. This method, however, did not yield satisfactory results in the case of very volatile bodies, and the composition of these substances had to be determined, as before, by eudiometric methods. We are indebted to Saussure for improving this branch of analysis, and for determining accurately the composition of several compounds, such as that of alcohol.^ He also analysed non-volatile bodies, some of them with great exactitude, by com- bustion in oxygen, determining the volume of this gas needed for the combustion, as well as that of the carbon dioxide formed.^ 41 Berzelius's Method. Saussure's method would probably have come into general use had not Berzelius^ published in 1814 his much more exact method for the analysis of organic bodies. It has already been stated in the introduction that Berzelius began this investigation with the view of ascertain- ing whether organic bodies obey the same laws of chemical combination as those which regulate the formation of in- organic substances. Adopting Lavoisier's plan, he absorbed the water and carbon dioxide formed by the decomposition, determining their amounts gravimetrically. Like Gay-Lussac and Thenard, he employed potassium chlorate as an oxidising agent, reducing the violence of its action by mixing it with ten times its weight of common salt. At the closed end of his glass combustion-tube he placed some of this mixture of 1 Ann. Chilli. Ixxviii. 57. ' Bibl. Britan. hi. 333. » 'lliomsou's Ann. Phil. [4], 401.