LUMINOUS PAINT. 2G9 



dark figures round it, and dark hands stretching across, by which the 

 time of the night might possibly be discovered there or thereabouts. 

 This invention has already appeared in a great many paragraphs, but, 

 hitherto, upon very few clock-faces. 



Recently it has assumed a more ambitious form patented, of 

 course. The patentees claim an improved phosphorescent powder, 

 which is capable of being worked up with the medium of paints and 

 varnishes, and thus applied, not merely to clock-faces, but to the 

 whole of the walls and ceilings of any apartment. In this case the 

 faintness of the light will be in some degree compensated by the ex- 

 tent of phosphorescent surface, and it is just possible that the sum 

 total of the light emitted from walls and ceiling may be nearly equal 

 to that of one mould candle. If so, it will have some value as a 

 means of lighting powder magazines and places for storage of inflam- 

 mable compounds. It is stated that one of the London dock com- 

 panies is about to use it for its spirit vaults ; also that the Admiralty 

 has already tried the paint at Whitehall, and has ordered two com- 

 partments of the Coinus to be painted with it, in order to test its 

 capability of lighting the dark regions of ironclad ships. 



This application can, however, only be limited to those parts 

 which receive a fair amount of light during the day, for unless the 

 composition first receives light, it is not able afterward to emit it, 

 and this emission or phosphorescence only continues a few hours 

 after the daylight has passed away ; five or six hours is the time 

 stated. 



A theatrical manager is said to be negotiating for the exclusive 

 right to employ this weird illumination for scenic purposes. The 

 sepulchre scene in tiobert le Diable, or the incantation in Der Frei- 

 schutz, or 21ie Sorcerer, might be made especially effective by its ghostly 

 aid. The name-plates of streets, and buoys at sea might be advan- 

 tageously coated with such a composition ; and many other uses sug- 

 gest themselves. 



There are rival inventors, as a matter of course. The French pat- 

 entees claim the use of cuttle-fish bones, various sea-shells, etc., 

 mixed with pure lime, sulphur, and calcined sea-salt, besides sul- 

 phides of calcium, barium, strontium, uranium, magnesium, or 

 aluminium. They also add phosphorus itself, though for what pur- 

 pose is questionable, seeing that this substance is only luminous 

 during the course of its oxidation or slow combustion, and after this 

 has ended the resultant phosphoric acid is no more luminous than 

 linseed oil or turpentine. An admixture of phosphorus might tempo 

 rarily increase the luminosity of a sample, but any conclusions based 

 upon this would be quite delusive. They also assert that electrical 

 discharges passed through the paint increase its luminosity. 

 According to some enthusiasts, electricity is to do everything ; but 

 these ladies and gentlemen omit to calculate the cost of rousing and 

 feeding this omnipotent giant. In this case electrical machinery for 

 stimulating the paint for anything outside of lecture-table experi- 

 ments or theatrical and other sensational displays, would be a com 

 mercial absurdity. 



The Americans, of course, are reinventing in this direction, but 

 Mr. Edison has not yet appeared on the luminous-paint scene. If 

 he does we shall doubtless hear of something very brilliant, even 

 though we never see it. In the mean time wo may safely hope that 



