Boracic Acid with Oxide of Lead. 379 



ing the white flocculent precipitate which remained upon the 

 filter with lukewarm water, the new salt was obtained in a 

 state of purity. 



This, when examined under a microscope of high power, 

 was found to consist of exceedingly minute irregularly-acicular 

 crystals, which depolarized light and possessed a nacreous 

 lustre. 



The compound thus obtained does not appear to be acted 

 upon by cold water ; boiling water, however, slowly but gra- 

 dually decomposes it into its constituent salts. It is perfectly 

 insoluble in alcohol. It dissolves with facility in hot dilute 

 nitric acid, being decomposed, and chloride of lead set free, 

 which, upon cooling, separates from the solution in long 

 needle-formed crystals. When heated to from 250° to 300"' F., 

 it loses about 3*59 per cent, of water, and then becomes anhy- 

 drous. At a low red heat it readily fuses into a clear amber- 

 coloured globule ; this, upon cooling, solidifies into a trans- 

 parent and almost colourless glass, which is slightly opales- 

 cent. When heated to redness, however, on charcoal, or in 

 an open platina capsule, it behaves differently ; white fumes 

 are now given off, and the fused mass becomes gradually 

 darker in colour, and of a thicker consistence, until it very 

 much resembles melted sulphur in appearance. If it be now 

 allowed to cool, it will be found to have undergone a very 

 considerable change ; it rapidly concretes into an opake, straw- 

 coloured brittle mass, which is made up of a multitude of long, 

 radiating, acicular crystals, and bears a striking resemblance 

 to molybdic acid. 



The crystallized hydrated salt, dried by exposure to sul- 

 phuric acid at the ordinary temperature, yielded upon ana- 

 lysis the following numbers : — 



I. 4*42 grs. were taken, and heated to redness in a tube of 

 Bohemian glass ; the aqueous vapour having been drawn off 

 by suction, and the apparatus allowed to cool, it was found to 

 have lost 0-180 gr. in weight=4<'072 per cent. 



II. 3*86 grs., treated as before, lost 0*12 gr. in weight 

 = 3*109 per cent. 



III. 5*00 grs. were dissolved in boiling dilute nitric acid, 

 and the solution was precipitated by nitrate of silver; Ag, CI, 

 (fused) =2-60 grs. in weight =0-64.11 Cl= 12*822 per cent. 



IV. 3-32 grs., treated as above, gave of Ag CI 1*82 grs. 

 = Cl 0-4487 gr.= 13-515 per cent. 



V. 4-581 grs. gave of FbO, SO^ 4*824 grs. = Pb 3-3009 

 = 72-0580 per cent. 



VI. 3-6 grs. gave of PbO, SO^ 3-833 grs. = Pb 2-6226 grs. 

 = 72-8510 per cent. 



