THE 

 LONDON, EDINBURGH and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



[THIRD SERIES.] 



JULY 1848. 



I. On Alpha- and Beta-Orcine. 

 By John Stenhouse, Esq., Ph.D.* 



A 



PAPER on the lichens, read before the Royal Society 

 about three months ago, contained among other matters 

 some observations upon orcine, and described an easy method 

 of procuring that interesting substance in a perfectly colourless 

 state. In the present notice, I purpose narrating a few obser- 

 vations I have subsequently made, and to describe a new 

 species of orcine derived from usnic acid, to which I have 

 given the provisional name of beta- orcine. 



The usual mode of preparing alpha-orcine is by boiling 

 lecanoric, erythric, or any of the similar principles of the 

 lichens, with an excess of lime or baryta. The orcine obtained 

 in this way is always more or less coloured. Without enter- 

 ing into the minute details of the process for preparing the 

 colourless orcine, which are fully given in the paper already 

 referred to, I only remark in passing, that it may be readily 

 procured by boiling the alpha- and beta-orsellesic, or the ery- 

 threlesic acids, in pure water from half an hour to an hour, 

 when a great deal of carbonic acid is given off; and on the 

 solutions being concentrated and set aside, abundance of cry- 

 stals of colourless orcine are deposited. If a little animal char- 

 coal is kept in the solution while it is being concentrated, it 

 will be found useful in preventing any tendency to oxidation. 



A quantity of colourless orcine prepared in this way was 

 dried at the ordinary temperature, and analysed with chro- 

 mate of lead. 0332 grm. substance dried at 60° F. gave 

 0*717 carbonic acid and 0*204 water. 



* Communicated by the Author. 

 Phil. Mag. S. 3. Vol. 33. No. 219. July 1 848. B 



/ 



