86 Intelligence and Miscellaneous Articles. 



formed by the waves beating against the mountains during their 

 elevation. 



Lastly, referring to the angular erratic blocks on the sides of the 

 Jura, &c., the author points out that he removes the only serious 

 difficulty opposed to the views of those who have supposed them to 

 have been transported by floating ice, by showing that the levels at 

 which those blocks are found were below the sea for a long period 

 at the epoch of their removal. 



X. Intelligence and Miscellaneous Articles. 



TWO PROCESSES BY WHICH THE PH^ENOMENON OF COLOURED 

 RINGS MAY BE PRODUCED WITH GREAT INTENSITY. BY M. 

 CARRE RE. 



WHEN a drop of a solution of bitumen of Judea in a mixture of 

 benzine and oil of naphtha is let fall upon the surface of 

 some water in a vessel, a very brilliant luminous phaenomenon is 

 seen to be immediately produced. The bituminous liquid extends 

 regularly in a thin film on the surface of the water, and thus pro- 

 duces very bright colours. The colour furnished by the film changes 

 every moment for a minute or two, because a portion of the benzine 

 and oil of naphtha evaporates, and the thickness of the film dimi- 

 nishes. But in a little time the film itself is completely solidified, 

 from the oxidizing action of the air. 



This delicate solid film may be easily fixed upon paper. Thus, 

 supposing that it has been produced in a tub at the bottom of which 

 there is a socket with a stop-cock, and which also contains a stool, 

 upon which, immersed in the water, rests the leaf of paper to be 

 coloured ; the film having been formed above the paper, all that is 

 necessary to fix it on the paper is to open the stop-cock. 



To obtain a regular coloration of the paper by means of the bitu- 

 minous film, it is very important that the latter should be very co- 

 herent. I increased its cohesion by introducing a certain amount of 

 caoutchouc into the solution of bitumen of Judea. 



I also obtain the phaenomenon of coloured rings with great bril- 

 liancy by exposing to the air hot and freshly-filtered common ink, in 

 which sugar is the principal adhesive matter. This process may serve 

 for the study of the phaenomenon of coloured rings. In fact, as the 

 thickness of the film which forms at the surface of the ink only increases 

 very slowly, we may very easily and exactly determine the order in 

 which the different tints produced by a homogeneous film succeed 

 each other in proportion as its thickness augments. I have also suc- 

 ceeded in fixing on paper the film produced by ink ; but as in this 

 case the cohesion of the pelhcle is very slight, I have only succeeded 

 by taking the following precautions : — 



1 . I do not deposit the film upon the paper until it has acquired 

 a great thickness. 



