FLASHLIGHTS 341 
0.3mm thick (1/25 to % inch). Typical mixtures are as 
follows (Novak) : 
Magnesium 2.5, cerium nitrate 1.75, strontium carbonate 
0.75; burns in 5% seconds. 
Magnesium 2.5, cerium nitrate 1.5, strontium carbonate 1; 
burns in 4.5 seconds. 
Magnesium 2.5, cerium nitrate 1.25, strontium nitrate 1; 
burns in 1.3 seconds. 
Magnesium 2.5, strontium nitrate 1, strontium carbonate 1; 
burns in 1.3 seconds. 
Magnesium 2.5, strontium nitrate 1, strontium carbonate 
1.5; burns in 4.3 seconds. 
Magnesium 2.5, magnesium carbonate 2.5; burns in 11.2 
seconds. 
Anhydrous salts must be used in all cases. 
So-called orthochromatic candles can be prepared by in- 
corporating certain salts, which give coloured lights. For 
red, lithium carbonate 1, with the strontium mixture given 
above. For yellow, sodium nitrate 5. For green, cupric 
sulphate 2, barium nitrate 2. 
SLOW-BURNING PowbDErs.—Slow combustion of flash pow- 
ders is also obtained by an admixture of shellac; for instance, 
1 part of shellac is melted by heat with 9 parts of strontium 
nitrate stirred in, allowed to cool, and powdered. Or mag- 
nesium 6, potassium chlorate 12, antimony sulphide 2; or 
magnesium 2.5, strontium nitrate 5, strontium carbonate 2.5, 
amorphous phosphorus 0.25, have also been recommended ; 
but the fumes are poisonous. Bethge patented the following 
mixtures, of which 2 to 3g burn in 30 seconds: magnesium 
2.5, cerium oxalate 1.5; magnesium 2.5; cerium oxalate 1.5, 
vanadic acid 0.08; magnesium 2.5, cerium oxalate 1; mag- 
nesium 2.5, calcium oxalate 0.75; magnesium 2.5, cerium 
oxalate 0.5, calcium oxalate 0.5; magnesium 2.5, manganese 
