402 Scientijic Intelligence — Arts. 



yield chemical principles, allied in character, but of different com- 

 position ; shewing that the organic nature is even more prolific in 

 chemical than in botanical species. From a South American variety 

 of Roccella tinctoria Dr Stenhouse obtains new acids, named by him 

 Alpha- orsellic and Alpha-orsellesic ; from a Cape of Good Hope 

 variety. Beta-orselUc and Beta-orsellesic, and a neutral principle 

 Roccellinin. The Evernia prunastri yielded evernic and evernesic 

 acids, the Usneas usnic acid, &c. The author recommends that the 

 extraction of the colouring principles should be performed in the 

 countries where the lichens grow, by cutting them up into small 

 pieces, macerating in milk of lime, neutralising the solution obtained 

 by muriatic or acetic acid, collecting the gelatinous precipitate which 

 falls on cloths, and drying it at a gentle heat. Thus the carriage of 

 the original bulky lichen would be, in a great measure, saved. The 

 commercial value of these lichens also varies excessively, according to 

 the proportion of colouring matter producible from them. This, he 

 finds, may be accurately determined for trade purposes, by macerat- 

 ing a constant weight of the lichen in milk of lime, filtering and 

 adding a solution of bleaching powder of known strength, from an 

 alkalimeter, till all colour disappears, and noting the quantity of so- 

 lution required. He thus found samples of the following lichens to 

 have proportional values assigned to them : — 



Angola lichen • . required 200 measures, value 1*00 

 American ...... 120 ... ... 0'60 



Cape 35 0-17 



Lecanora Tartarea (Giessen) ... 25 ... ... 0'12 



—AthentBum, No. 1061, p. 217, February 26, 1848. 



21. Stereochromy. — A communication from Professor Schottlauer, 

 of Munich, acquaints us with particulars of a new invention for paint- 

 ing upon walls, discovered by himself, conjointly with Herr Fuchs, 

 Counsellor of the Mines, to be called stereochromy. Its peculiarities 

 are stated as follows : — Far greater ease in its manipulation than fres- 

 co. The ground is not laid in patches, but by one single operation. 

 The colours, prepared in distilled rain-water, take such firm hold as 

 not to be disturbed or altered by any subsequent washings or shades, 

 while the process of painting may be carried on with any amount of 

 intervals, thus rendering a far richer finish possible than with fresco, 

 After the picture is finished, it is saturated with a fluid, which unites 

 the ground and the colour into a mass of the consistency of stone, 

 desiccation being thereby rendered impossible. The colours are of 

 greater strength and brightness than with fresco, though without the 

 slightest glare or reflection, as of oil. It resists all atmospheric in- 

 fluences, humidity, evaporation, &c. ; a test, no less extreme than 

 the burning of alcohol has been applied to it, without the slightest 

 change or deterioration. — Atheneeum, No. 986, p. 820. 



22. Melon Wine. — A paper was received by the Paris Academy of 



