318 Intelligence and Miscellaneous Articles. 



prisms, the terminal edges being replaced by planes that produce 



four-sided pyramids on each base. 



This salt consists of — By Experiment. Calculated. 



Boracic Acid - - - 46*4 47 



Potash 21-G 21-0 



Water 32-0 320 



100-0 100-0 



The formula is 3 B"- Qs + K O + 8 H« O. 



These crystals are unalterable in the air, and, like the preceding, 

 they fuse readily, and swell but little. 



Rhombic Biborate of Potash. This salt, the composition of which 

 corresponds to that of octahedral borate of soda, possesses, neverthe- 

 less, a different and an incompatible form ; it generally crystallizes 

 in hexagonal prisms, and rarely as an acute rhomboid — primary 

 form, an acute rhomboid occasionally with the lateral angles re- 

 placed, or as a bipyramidal dodecahedron or hexagonal prism. 



This salt is alkaline, very soluble in cold and in boiling water ; 

 when fused it swells up like borax ; it is composed of — 



By Experiment. Calculated. 



Boracic Acid ... 43-7 43-2 



Potash 28-5 29-5 



Water 27-8 27-8 



100-0 1000* 



The formula is 2 B'^ 0^ + K + 5 H^ O, 



Sexborate of potash does not precipitate magnesia, oxide of man- 

 ganese or oxide of silver, from solution ; the following are the effects 

 which it produces in the annexed metallic solutions : — 



Barium "| A white precipitate, which disappears on the 

 Strontium > addition of excess of water ; the solution 

 Calcium J becoming slightly alkaline. 

 Peroxide of iron, a rusty yellow precipitate. 

 Copper, bright blue ditto. 



Nickel, greenish. 



Chromium, green. 



Lead, white. 



Silver, white, which disappears on the addi- 



tion of excess of water. 



An. de Ch. et de Ph. 67—215. 



CYANIDE OF GOLD. 



M. Deferre prepares this compound by dissolving IG parts of 

 gold, cut into small pieces, in 80 parts of aqua regia, heated in a 

 sand-bath ; to the solution there are to be added 24 parts of cya- 

 nide of mercury, dissolved in 24 parts of distilled water ; the whole 

 is to be evaporated to dryness, and the residue treated with 192 



* There is a mistake here in the original ; the substances amount to 

 100-5. 



