246 THE CANADIAN NATURALIST. [June 



crate of potash is required, while for gunpowders its proportion 

 varies from 8 to 15 per cent. This component (picrate of potash) 

 ^s of a beautiful goldon-yellow colour,and crystallizes into prisma- 

 tic needles possessing a brilliant reflection ; it is insoluble in alcohol, 

 but soluble in about 260 parts of water at 15° or 14 parts of boi- 

 ling water. Heated with care, it becomes orange-red at a tempe- 

 rature of 300°, but on cooling, it assumes its original colour. 

 Heated to 310°, it detonates wifh violence. The researches of 

 M. John Casthellaz on the action of nitric acid on phenic acid 

 improved the method of manufacturing picric acid, and produced 

 chemically pure picrate of potash at such a reasonable price that 

 the new powders are not more expensive than ordinary black pow- 

 der. 



MM. Designolle and Casthellaz give the following proportions 

 for preparing deflagrating mixtures with coloured flames : — 



Golden fire 

 Green fire 

 Red fire 



Picrate of ammonia . 50 



Picrate of iron . . 50 



Picrate of ammonia , 48 



Nitrate of barytes . 52 



Picrate of ammonia . 54 



Nitrate of strontian . 46 



Chemical News ; abstracted from the Bulletin de la Societe 

 d'e^icotiragement. 



MISCELLANEOUS. 



Mr. Sorby's Blow-Pipe Bead Crystals. — These ex- 

 quisitely beautiful Miscroscopic objects are prepared by fusing 

 borax in a circular loop of platinum wire, and adding various 

 earths and minerals thereto, in such proportion that they are 

 entirely dissolved at a high temperature, but partially deposited, 

 when kept for some time, at a heat below dull redness. The 

 beads should be about |th inch in diameter, and Jrd that thickness. 

 After having obtained crystals of a satisfactory character, the 

 ring-shaped loop may be cut off', and the bead mounted in a 

 cell with Canada Balsam. When thus mounted, they may 

 be thoroughly examined with a | inch or ttj object glass and 



