1869.] MlSCELLANEOtfS. 247 



achromatic condenser. The full beauty of the specimen can only 

 be seen with a binocular miscroscope ; and few objects are better 

 fitted to show the advantage of that kind of instrument. The 

 crystals then stand out in perfect relief, and are seen to be equally 

 complicated in all directions. 



Fews objects of the kind are more easily prepared than the 

 crystals of borate of magnesia deposited from borax saturated with 

 magnesia, They first form as thin prisms, and smaller crystals 

 are afterwards deposited, so as to give rise to objects very much 

 like a handle with a brush at each end. 



Zircon or zirconia fused with borax yields crystals of the 

 borate. In their most rudimentary state they are small prisms 

 with a simple cross at each end, which afterwards becomes 

 complicated. 



The crystals of molybdate of zirconia, formed by fusing zir- 

 conia in borax with molybdic acid, are extremely elegant and 

 beautiful objects. They are so delicate that their own weight 

 would probably break them, if they were in an aqueous solution ; 

 but being supported in solid borax, like the insects enclosed in 

 amber, they are secure from all enjury. 



Scheelite — native tungstate of lime — fused in borax, is 

 deposited in crystals of great beauty, and is an object easily pre- 

 pared. 



The molybdate of strontia, produced by fusing strontia and 

 molybdic acid in borax, crystallizes in long spindle-shaped crystals ; 

 whereas the molybdate of lime yields very different crystals, of an 

 intermediate form. 



Apatite — native phosphate of lime— fused with borax, deposits 

 in crystals which vary much in shape. Six-sided stars are 

 often formed on the surface, and needle-shaped crystals grow 

 from their centres into the interior of the borax, so that they 

 look like nails with highly ornamented heads driven down into 

 the bead. "When formed with their axis parallel to the sur- 

 face, the crystals are sometimes much like diatomacece. The 

 addition of phosphate of soda to a borax bead containing lime, 

 in almost any state of combination, gives rise to similar crys- 

 tals. 



On adding a certain amount of carbonate of soda to quartz or 

 various silicates dissolved in borax, crystals are deposited, which 

 vary much according to circumstances : but they all seem to be 

 due to the variable growth of many small six-sided prisms with 



