Progress of Invention, 471 



moistening modelling clay. The product thus obtained will possess 

 all the good qualities of wax, "but will Tbe considerably less expensive ; 

 and it will be superior to it, in remaining of the same consistence at all 

 temperatures. Before the glycerine is added to the clay, the latter 

 must be well 'dried and pulverized. Any water left in it would 

 subsequently destroy the plasticity ; as it would pass off by evapo- 

 ration, and thus leave the clay without sufficient fluid to secure to 

 it a proper consistence. 



New Mode op Producing Light for Photographic Purposes. — 

 The discovery of the excellence of magnesium as a means of pro- 

 ducing light has been of great advantage to the photographer ; but 

 its utility is still greatly limited by its cost, notwithstanding the 

 improvements that have been made in the mode of obtaining it. A 

 source of light which is very much less expensive, and which is 

 extremely convenient, when a large mass, such as a landscape, is 

 to be taken at night — which would require the consumption of large 

 quantities of magnesium — has recently been discovered by M. 

 Sayers. Twenty-four parts by weight of nitrate of potash, seven 

 parts flowers of sulphur, and six parts red sulphuret of arsenic are 

 thoroughly mixed. This composition, when set on fire, affords a 

 most brilliant light ; and the negatives it produces give most 

 excellent positives. The contrast between the lights and shades, 

 which with artificial light is liable to be very great, may be easily 

 softened down, by igniting at once two portions of the mixture ; 

 one the more powerful, to light up the subject, and the other to 

 modify .the tones ; an agreeable effect will thus be secured. It 

 has been found that about half a pound of the mixture will afford 

 light for half a minute — a space of time abundantly sufficient for 

 ordinary purposes. 



Further Utilization op the Aniline Dyes.— The beautiful 



colours derived from aniline have already received a very general 



application ; but they have been, hitherto, unsuitable to one purpose 



which, of all others, would be most likely to benefit by the brilliant 



effects they produce — oil painting. They are now, in consequence of 



a recent discovery, very likely to become extremely useful in this 



branch of art. It has been found that a solution of aniline is 



capable of dissolving caoutchouc, and all the resins which have 



acid properties, and also the aniline dye stuffs. The application of 



this important fact is obvious. For example, the solution of shellac 



in aniline may be coloured by the addition of the concentrated 



solution of aniline dye stuff; the result" being a transparent paint, 



which answers admirably for glass, porcelain, etc. This shellac 



solution may be mixed with any oil paints that contain no lead ; 



and thus an oil paint of extraordinary brilliancy may be obtained. 



"With the exception of fuschine, which, if heated with shellac, is 



changed to blue, all the aniline dyes may be dissolved in tbe 



aniline solution of shellac itself. When, however, fuschine is to be 



used, it must be dissolved in aniline without heat, and its solution 



then be mixed with the shellac solution. 



Origin op the Staffordshire Iron Ores. — The source whence the 

 iron ores of the Staffordshire coal measures have been derived 



