Volume 1

A system of chemistry / by Thomas Thomson.

  • Thomas Thomson
Date:
1802
Catalogue details

Licence: Public Domain Mark

Credit: A system of chemistry / by Thomas Thomson. Source: Wellcome Collection.

Provider: This material has been provided by King’s College London. The original may be consulted at King’s College London.

    47/532 page 29
    crystals. Now sulphur is capable of crystallizmg. If \ Chap. IL^^ it be melted, and as soon as its surface begins to con- geal, the liquid sulphur beneath be poured out, the in- ternal cavity will exhibit long needle-shaped crystals of an octahedral figure. This method of crystallizing sul- phur was contrived by Rouelle. When sulphur is heated to the temperature of 302° Converted in the open air, it takes fire spontaneously, and burns t,^j,'^^Jj^ with a pale blue flame, and at the same time emits a acid great quantity of fumes of a very strong suffocatiiog odour. When heated to the temperature of 570°, or when set on fire and then plunged into a jar full of oxygen gas, it burns with a bright white flame, and at the same time emits a vast quantity of fumes. If the heat be continued long enough, the sulphur burns all away without leaving any ashes or residuu7n. If the fumes be collected, they are found to consist entirely of sulphuric acid. By combustion, then, sulphur is con- verted into an acid *. This fact was known several centuries ago, but no intelligible explanation was given of it till the time of Stahl. That chemist undertook the task, and founded on his experiments a theory so exceedingly ingenious, and supported by such a vast number of facts, that it was in a very short time adopt- ed with admiration *by all the philosophic world, and contributed not a little to raise chemistry to that rank arnong the sciences from which the ridiculous preten- sions of the early chemists had excluded it. * Acids are a class of compound bodies to be afterwards described. They are distinguished by a sour taste, and by the property which they possess of changing the blue colour of many vegetable infusions (of the flowers of mallows for instance, or red cabbage) to red.
    digitised image 1
    digitised image 2
    digitised image 3