A history of chemistry from the earliest times till the present day / by the late James Campbell Brown; with a portrait and one hundred and six illustrations.

  • James Campbell Brown
Date:
1913
Catalogue details

Licence: In copyright

Credit: A history of chemistry from the earliest times till the present day / by the late James Campbell Brown; with a portrait and one hundred and six illustrations. Source: Wellcome Collection.

    313/588 page 273
    ]. An internal, cold, conical, central portion of unconsumed gas. 2. A shell of burning gas, in which the more combustible constituents (those which when mixed with air take fire at the least elevated temperature), are burnt, chiefly hydrogen, thus evolving an intense heat; but the supply of air at this shell being limited, if there is much carbon it is separated in fine particles, which at the high temperature glow and emit light. 3. An outer shell, where these hot particles, meeting with a plentiful supply of air, burn, emitting heat but no light. Several interesting questions arise out of these facts. What are the intermediate products in different circumstances 1 How do other combustible substances besides hydrogen and carbon burn ? What are the ultimate products of the com- bustion of each ? These and other similar questions have not yet received a complete answer. When sufficient air is admitted into admixture with the combustible gas before reaching the flame, as by the blowpipe or the Bunsen burner, the flame consists of two parts only—the interior part is not a shell of half-burning material ; not only hydrogen but some other substances are burned ; the carbon is half burned to carbon monoxide, and the blue colour of its heated vapour is seen. The outer flame consists of the hot products of its complete combustion. The most recent device for facilitating researches of this kind is that invented by Professor Smithells. Faraday em- ployed a small glass tube as a syphon for drawing off the half- burnt products of combustion from the interior of a flame, but the apparatus of Professor Smithells enables more accurate results to be obtained. While the nature of phenomena, and the details of the properties and changes of substances, are being made better known and more familiar to us every day, it is only m a very limited sense that we can be said to understand them. We have come to know how bodies act, and therefore we cease to wonder at the results of that action. But we do not yet possess H.c. 18
    digitised image 1
    digitised image 2
    digitised image 3