Sels mixtes

Homberg used this axiom in chemistry to classify salts by the ana-lytic/synthetic procedures. Acids combined with fixed alkali salts or lix-ivial salts, earthly or metallic alkalis, and metals to produce mixed salts [sels mixtes], also called middle salts [sels moyens], which were in part fixed, in part volatile.Homberg characterized the production of middle salts as fixation of volatility rather than as neutralization of acidity, diverging somewhat from Lemery s definition of the term. The attention to the physical rather than the chemical characteristics of substances and their reactions set him apart from most chemists. Applying the physical criteria of volatility and fixedness, he placed sal ammoniacs (another commonly accepted salted salt ) in a separate category because they had two volatile components, which rendered them volatile ... 

Sabatier, P. Action d un oxyde ou d un hydrate m6talUque sur les solutions des sels des autres metaux. Sels basiques mixtes. C. r. hebd. Stances Acad. Sci. 132. 1538 (1901). 

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