IV. Note on the spectrum of carbonic acid

• Published in: Proceedings of the Royal Society of London
• Format: Article in Journal/Newspaper
• Language: English
• Published: The Royal Society 1881
• Subjects: Dewar; Hagen; Smyth; Carbonic acid
• Online Access: http://dx.doi.org/10.1098/rspl.1881.0034; https://royalsocietypublishing.org/doi/pdf/10.1098/rspl.1881.0034

The well-known spectrum first observed by Swan at the inner cone of a number of flames produced by burning liquid and gaseous combinations of carbon, has been ascribed by Messrs. Attfield and Watts to the element carbon itself; while several other natural philosophers, amongst whom I only mention Messrs. Thalén and Angström, P. Smyth, Liveing and Dewar, believe it to be due to some combination of carbon with hydrogen. The fact that the bands and lines of Swan’s spectrum are seen even when oxide or binoxide of carbon is made luminous in a Geissler tube by means of an electric current, the last-named gentlemen explain as being caused by the gases not having been entirely deprived of all moisture when introduced into the vacuum tube. I therefore believed it to be not altogether without interest to make some experiments on carbonic acid dried with the utmost care. For this purpose I used a mercurial pump, as invented by Professor Toepler, with some slight changes in the original construction indicated by Dr. Hagen, which enables us not only to obtain the most perfect vacua, but also to avoid every cock or junction by slided pieces, which must be greased in order to be hermetic, so that no vapours and gases containing carbonic matters arising from the grease, either by increase of temperature or by the electric current when passing the vacuum tube, would render impure the carbonic acid, as is the case with the common Geissler pumps. Carbonic acid was produced in the well-known manner from marble and diluted muriatic acid in a Kippian apparatus, well washed with water in a large Woolf’s bottle, and then sent through concentrated sulphuric acid, three tubes of U form containing chloride of calcium, and a double tube half filled with anhydride of phosphoric acid. To this last tube were fastened, by means of sealing, two Geissler glass cocks, being on the other side fastened by sealing to a valve of sulphuric acid, that prevented all vapours coming from the cocks from entering the vacuum tube. After all air had been ...