8 REPORT 1867. 



■\ai'ious remarkable movements of the films, upwards and downwards, when they 

 are formed upon conical vessels open at both ends. 



Notice respecting the Enamel Pliotocjraphs executed hi/ Mr. M'Sau', of Elin- 

 hurgli. By Sir David Brewster, K.H., LL.D., F.R.S., 4'e- 

 In order to give permanence to photographs, various attempts have been made to 

 burn theln into glass or porcelain. M. Joubert and M. Lafon-Camersac some 

 time ag;o produced very fine pictures by this process ; and more recently, M. Ober- 

 metter and M. Grune, of Berlin, have been ec[ually successful. Oiu- coimtiTman, 

 Mr. "SVilliam M'liaw, has also succeeded in obtaining very excellent pictures, which 

 v\ill bear comparison witli those produced by the best foreign artists, and he has 

 requested me to exhibit specimens to the Section. ]\L-. M'Eaw believes that his 

 process is similar to that of Camersac, which is kept secret, and he claims no other 

 merit than that of being the first Britisli artist who has succeeded, in this branch 

 of photography. His pictures are produced in any enamel colour, and although, 

 before they are fired, they can be rubbed off like daguerreotype, yet the burning 

 lixes them immoveably, while the fusion of the picture gives it "its characteristic 

 transparencj-. From some experiments which he has abeady made, Mr. M'Raw is 

 sanguine that the pictures may not only be produced in monochrome, but that they 

 may be simply tinted and finished with the various colours biu-ned in. Althouo-h 

 the specimens are chiefly on glass, yet they can be transferred to any surface or sul)- 

 stance that will stand the firing, such as enamelled copper articles of porcelain. 



On the Motions and Colours upon Films of Alcohol, Volatile Oils, and other 

 Fluids. By Sir David Breavster, K.H., F.E.S., ^-c. 



In a paper " On the Phenomena of thin Plates exposed to Polarized Light," 

 pubhshed in the Philosophical Transactions for 1841, tlie autlior observed certain 

 motions and colours upon some of the volatile and fixed oils, the cause of which he 

 did not attempt to discover. Their apparent similarity to the molecidar movements 

 and colours, described in a preceding paper, induced him to resume the subject. 



_ When a drop of alcohol is placed upon an aperture the fifth of an inch in 

 diameter or less, a concave lens will be formed upon it. As the alcohol evaporates, 

 a very small plane film will appear- in the centre, and will gradually increase till it 

 fills the aperture. If held in a vertical or even inclined position, and examined by 

 ti-ansnutted Ught, a current of fluid, without colour, A\ill be seen issuing from the 

 margin of the film, moving quickly to difi'erent parts of its circumference, some- 

 times dividing itself into two currents dancing opposite one another, and then ex- 

 tending into secondary currents in constant motion. Similar currents are produced 

 upon various alcoholic .solutions and a large number (seventy to eighty) of volatile 

 oils, &c. 



If we now examine the film by reflected Hght, the principal and secondaiy cur- 

 rents will be seen as before, but accompanied with systems of coloured rings of 

 gi-eat beauty, shifting their place on the film, sometime^ in rotation, expanding^and 

 contracting quickly, and changing their form and colour. 



In small films there is often only one system of rings contracting and expanding 

 with a constant variation of the central tint. In general, however, there are two, 

 three, or several systems— each system being produced by a secondaiy current 

 giving morion to the colouring-matter on .the surface of the film. In some cases 

 the motions and colours disappear, the film becomes coloiuless, and tadpoles issue 

 from its margin as on the soap-bubble ; but in general the film bursts before this 

 talces place. The colourless currents and the colours into wliicli they expand are 

 supposed by the author to have the same origin as those upon the soap-bubble. The 

 paper was illustrated by drawings of the currents and of the systems of rin"-s. 



On the Jiadiant Spectrum. By Sii- David Brem-ster, K.H., LL.D., F.R.S.. ^t. 

 _ I have given the name of Radicmt Spectrum to a phenomenon which I discovered 

 in 1814, and which I described to the Eoyal Society of Edinburgh in the early part 

 of that year. ' ' ^ 



