A dictionary of chemistry, on the basis of Mr. Nicholson's: in which the principles of the science are investigated anew, and its applications to the phenomena of nature, medicine, mineralogy, agriculture, and manufactures, detailed (Volume 1).

  • Ure, Andrew, 1778-1857.
Date:
1821
Catalogue details

Licence: Public Domain Mark

Credit: A dictionary of chemistry, on the basis of Mr. Nicholson's: in which the principles of the science are investigated anew, and its applications to the phenomena of nature, medicine, mineralogy, agriculture, and manufactures, detailed (Volume 1). Source: Wellcome Collection.

Provider: This material has been provided by the National Library of Medicine (U.S.), through the Medical Heritage Library. The original may be consulted at the National Library of Medicine (U.S.)

    25/432
    DICTIONARY OF CHEMISTRY ABS ABSORBENT. An epithet introduc- ed into chemistry by the physicians, to designate such earthy substances, as seemed to check diarrhoea, by the mere absorption of the redundant liquids. In this sense it is obsolete and unfounded. Professor Leslie has shown that the facul- ty of withdrawing moisture from the air, is not confined to substances which unite with water in every proportion, as the strong acids, dry alkalis, alkaline earths, and deliquescent salts; but is possessed by insoluble and apparently inert bodies, in various degrees of force. Hence the term Absorbent merits a place in chemical no- menclature. The substance whose absorbent power is to be examined, after thorough desicca- tion before a fire, is to be immediately transferred into a phial, furnished with a well ground stopper. When it is cooled, a portion of it is transferred into a large wide-mouthed bottle, where it is to be closely confined for some time. A deli- cate hygrometer being then introduced, indicates on its scale the dryness produced in the inclosed air, which should have been previously brought to the point of extreme humidity, by suspending a moist- ened rag within the bottle. The following table exhibits the results of his experi- ments :— Alumina causes a dryness of 84 degrees. Carbonate of magnesia . . . 75 Carbonate of lime 70 Silica 40 Carbonate of barytes 32 Carbonate of strontites .... 23 ripe clay 85 Orecnstone, ortrap in powder 80 A ABS Shelly sea sand 70 degrees. Clay indurated by torrefaction 35 Ditto strongly ignited 8 Greenstone ignited 23 Quartz do 19 Decomposed greenstone ... 86 Greenstone resolved into soil 92 Garden mould 95 The more a soil is comminuted by labour and vegetation, the greater is its absor- bent power. This ingenious philosopher infers, that the fertility of soils depends, chiefly on their disposition to imbibe mois- ture; and illustrates this idea by recent and by disintegrated lava. May not the finely divided state most penetrable by the deli- cate fibres of plants, derive its superior power of acting on atmospherical vapour from the augmentation of its surface, or the multiplication of the points of contact ? In similar circumstances 100 gr. of the following organic substances absorb the following quantities of moisture: Ivory 7 gr. boxwood 14, down 16, wool 18, beech 28. —Leslie on Heat and Jlfoiztnre* Absorption. By this term chemists un- derstand the conversion of a gaseous fluid into a liquid or solid, on being united with some other substance. It differs from con- densation in this being the effect of mecha- nical pressure, or the abstraction of caloric. Thus, if muriatic acid gas be introduced into water, it is absorbed, and muriatic acid is formed; if carbonic acid gas and ammoniacal gas be brought into contact, absorption takes place, and solid carbo- nate of ammonia is produced by the union of their ponderable bases. There is a case of condensation, which has sometimes no doubt been mistaken for