SCIENTIFIC SUMMARY. 
203 
Determination of Oxygen in Organic. Analysis. — At the meeting of the 
Chemical Society of London, held on the 21st of February, Mr. E. T. 
Chapman read a paper, entitled u Limited Oxidation : Determination of the 
Oxygen Consumed,” which contained a suggestion for a more facile method 
of estimating oxygen in organic analysis than that in general use. The 
details are much too technical for our pages, hut we call attention to the 
paper, as perhaps interesting to those who are pursuing organic chemical 
investigations. 
The Formula for Purpurine has at last been settled as C 10 H 6 0 7 , thus 
putting an end to the controversy between M. Schiitzenbergen and M. 
Bolley. The latter now agrees to the formula above, but, in other details, 
there is still considerable difference between the views of these chemists. 
New Petroleum Compound . — Chimogene is the name of a new substance 
procured by condensing the gases first coming over from petroleum. It 
has been produced by Prof. Van der Weyde, of Girard College, U. S. The 
new liquid boils at 40°, and produces intense cold by evaporation. 
The Preparation of Tinctures . — On this important point some valuable 
observations have recently been made in the Journal de Pharmacie , by M. 
Filhol. It appears, from his inquiries, that many of the tinctures kept in 
our druggists shops and dispensed to patients must have very different 
qualities from those assigned to them in the treatises on Materia Medica. 
M. Filhol makes the following statements : — 
“ A tincture prepared from the leaves of a plant will be of a beautiful 
green colour, due to the presence of chlorophyll, and will, under the in- 
fluence of hydrochloric acid, undergo transformations, which M. Fremy 
has described, and which I have studied myself. Now, these transforma- 
tions do not take place in a tincture which has been prepared for several 
months, and the most essential characteristics of chlorophyll disappear. 
“ The petals of the ranunculus, macerated in alcohol, give a golden- 
yellow tincture, which, on the addition of an equal volume of hydrochloric 
acid, turns green. After the liquid has been filtered, a yellow substance 
remains on the paper, and the filtered liquid is of a pure blue colour. 
Nothing of this kind takes place when the tincture has been kept some time. 
Then the liquid remains yellow in spite of the addition of hydrochloric acid. 
In this case the xanthine of the flowers has been altered, as well as the 
■chlorophyll.” 
The Separation of Palladium and Copper . — A novel method for the 
separation of these metals has been discovered by Professor Wohler, and 
has been described by him in the pages of the Chemical News'. — The 
mixed liquids are dissolved in aqua regia, and the excess of nitric acid 
is driven off by heat. The liquid is then saturated with sulphurous acid 
gas, and a solution of sulphocyanide of potassium is added. This has no 
action upon the palladium, whilst it precipitates the copper in the form 
of a white subsulphocyanide, 0u 2 C 2 NS 2 . This may easily be changed into 
Cu 2 S or CuO, and the quantity of copper thereby ascertained. 
Amount of Carbonic Acid in the Air . — Some interesting observations have 
been carried out by Mr. T. E. Thorpe, and have been described to the 
Chemical Society (January 17). His experiments were conducted on the 
method of Pettenkofer, an aqueous solution of baryta being used to absorb 
