152 ANNUAL OF SCIENTIFIC DISCO\'ERY. 



NOVELTIES IN PHOTOGRAPHY. 



Photo grapliic LigJit. — A pure and very bright yellow light, used 

 when working with very sensitive chemicals, may be obtained in 

 the following simple and cheap manner: Two little pieces of 

 platinum wire, each ending in a little loop of one-sixth of an inch 

 in diameter, are placed in the flame of a Bunsen burner. By 

 placing a small lump of carbonate of soda in each of the platinum 

 loops, by the fusion of the soda the colorless flame at once assumes 

 an intensely j^ellow light. In such a flame a fused drop of car- 

 bonate of soda will last for a considerable time, hanging in the 

 platinum loop like a drop of clear water. This is one of the best 

 ways of producing a pure monochromatic flame. 



Photographs from a Balloon. — An experiment of great interest 

 in a topographical point of view has just been made by M. Tour- 

 nachon, the^ photographer, better known by the name of Nadar, 

 with the captive balloon at the Hippodrome. At a height of 300 

 metres (984 feet) he succeeded, in spite of the rotary motion of 

 the aerostat, in obtaining several photographic proofs, successfully 

 taken, representing most accurately the panorama of Paris. This 

 is an important step in a strategic as well as in a geodesic point 

 of view. 



Preservation of Photographs. — H. Cooper, Jr., of England, gives 

 the following formula for a preservative varnish which is stated 

 to be an entire protection against fading : — 



1 dram of gum dammar dissolved in 1 ounce of benzole. 



1 dram of paraffine dissolved in 1 ounce of benzole. 



Mix 4 parts of the paraffine solution with 1 part of the dammar 

 solution. 



Prints covered with this varnish are impermeable to water. 

 A solution of the paraffine only will do, but is better with the gum 

 dammar. 



THE SCIENCE OF EXTINGUISHING A FIRE. 



Experiments by M. Van Marum, in Holland, show that violent 

 conflagrations may be extinguished by very small quantities of 

 water, by means of buckets or small hand-pumps. The flame of 

 any burning substance must cease, according to well-known prin- 

 ciples and experiments, as soon as any cause prevents the atmos- 

 pheric air from touching its surface ; thus, when a small quantity 

 of water is thrown upon a body in a state of violent conflagration, 

 this water is at first parti}'' reduced to vapor, which, rising from 

 the surface of the burning substance, repels the atmospheric air, 

 and consequently represses the flame, which, for the same reason, 

 cannot again appear whilst the production of the vapor continues. 



From experiment it appears that the art of extinguishing a vio- 

 lent conflagration with very little water consists in throwing it 

 where the fire is most powerful, so that the production of vapor 

 from the water, by which the flames are smothered, may be as 



