144 ANNUAL OF SCIENTIFIC DISCOVERY. 



sidos ; from oac-li of these, profiles are cut out in thin sheet metal ; 

 eacli pair of prolilus is caused to i)lane away tiie sides of a Ijlock 

 of clay coiTcs])onding to the position in which their photograph 

 "was taken. I'lius, the clay conies to have on each side tlie same 

 jjrofde as that of the sitter, and is tlius a likeness rccjuiriiig but a 

 few toueiies from tlie artist to give it finish and exactness. 



The " carl)on printing" photograplfit; jjnxx'ss has been applied 

 to the ijcrmanent ornamentation of porctdain with success ; any 

 material fit for l)urning into that su!)stance being sul)slituted for 

 the carbon or India inl< of the original operation. — Frunklia Jour- 

 nal, January, 18G6. 



P/iottiipapJis iifthe Moon. — Mr. Warren De la Hue has obtained, 

 with ins tinrtccn-inih telescope, i>hotograplis of tlu; moon so ]jer- 

 feet that they l)car being cnlargcil to a iliameter of three feet ; and 

 they are foun<l so exact, w ht-n submitted to microuietrical exami- 

 nation, that they furnish correct data for the measurement of the 

 vibrations of the moon. They also serve as a foundation for the 

 lunar map, six fc»'l in diameter, undertaken under the auspices of 

 the British Association. 



New Artifi<i(tl Liijhifor PJiotofji-aphy. — 'Mr. Savers of Paris ob- 

 tains a ligiit almost ei[ual in power to that of magnesium, and 

 unich cheaper, from the comliustion of a mixture of twenty-four 

 jiarts of well-drii'd and powdered nitrate of potash with seven of 

 flowers of sulphur and six of red sulphuret of arsenic. The mix- 

 ture costs only twelve cents a kilogram. — Lcs Mondes, Jan. 4, 18GG. 



Light for P/totoyraphic Purposes. — A substitute for the yellow 

 glass, used by photographers to intercejit actinic rays, lias beea 

 suggested by W. Sidni'V (ribbons of Melbourne. This is a mix- 

 ture of gelatin and bichromate of jjotash, spread as a varnish 

 over their cotton cloth or similar material. 



In 2)reparing a window for the illumination of a photographer's 

 dark room, Oliyrnetter mixes an acid S(dution of sulj^hate of qui- 

 nine with some gum or dextrine, and paints the mixture over a 

 thin sheet of white paper. With this he covers the window 

 panes, and he states that, on the brightest day, a window so pre- 

 pared will allow no actinic light to pass. 



Varnish for Photographs. — ^I. liussi first brushes the pi'ints 

 over with a solution of gum araliic, and, when this is dry, applies 

 a coating of collodion. The following are the i)roportions re- 

 commended : — 



1. Clear transparent gum arabic, 25 grammes; distilled water, 

 100 cub. cents. ; dissolve and strain. 



2. Gun-cotton, 3 grammes ; alcohol, 60 grammes ; ether, 50 



grammes 



By this double varnish the inventor insures the preservation of 

 proofs. — Chemical News. 



Magic Photographs. — The familiar exi5criments of the labora- 

 tory have in the present day a great tendency to become the 

 magic of the drawing-room. Magic photographs are among the 

 most recent of the scientific toys which take the public attention. 

 These are of various kinds. The first and most common mode 

 of producing them consists in placing an apparently common 



