The chemical pocket-book, or memoranda chemica; arranged in a compendium of chemistry ... with Bergman's table of single elective attractions / as improved by Dr. G. Pearson.

  • James Parkinson
Date:
1807
Catalogue details

Licence: Public Domain Mark

Credit: The chemical pocket-book, or memoranda chemica; arranged in a compendium of chemistry ... with Bergman's table of single elective attractions / as improved by Dr. G. Pearson. Source: Wellcome Collection.

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    (ions of O to P, and N to Q; but if the force tending to unite O and P together added to that which tends to unite the com- pound O P to Q is more considerable thanjhat which originally united N O and P Q, there will be a decomposition: the ter- nary compound O P Qwill be formed, and one of the compo- nents, N, must be separated.—Fourcroy, 1802. Berthollet has discovered, that the affinities of bodies are affected by the proportion in which the bodies are employed : thus a body, in a quantity proportionably large, may effect the decomposition of a compound, which it would not do in a less quantity ; the quantity of the mass compensating for weakness of affinity. He has also ascertained, that the opposing substances divide that body which is the subject of combination—Insolubility, cohesion, and crystallization, modify the conditions of chemical action, by limiting the quantity of a substance to be brought into action in a liquid—Elasticity, by separating a part in an elastic state, which no longer affords any resistance, modifies the effects of affinity, in an opposite direction to the former—Solvents, water for instance, dissolve, according to their quantity, as well as affinity—The action of heat concurs with those of solvents in opposing the force of cohesion ; and, lastly, that—the quantity of a precipitate may depend on the proportion which the action ot that particular fluid bears to the force of cohesion in the precipitate. Tables of affinities having been constructed, without an at- tention to the proportions and the other conditions which con- tribute to the results ; these tables give a false idea of the de- grees of chemical action.—Anna/es de Chimie, 1801. EARTHS. The Earths arc of two kinds: those which possess simply the characters of earths, being diy, tasteless, inodorous, incombus- tible, nearly insoluble in water, and not more than five times heavier than water: and those which with these characters
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