404 Foreign and Miscellaneous Intelligence. 



triturate it, will become yellowish green, and all the mercury and 

 iodine will have disappeared. The alcohol will be almost entirely 

 evaporated, and a very fine protiodide will have been produced. In 

 this operation there is formed at first detitiodide mixed with iodine and 

 mercury ; the alcohol, by dividing the deutiodide and dissolving the 

 iodine, so as to form a very concentrated solution, brings the whole 

 into mutual contact, and very promptly determines the combination 

 of the two bodies. 



When 100 parts of the deutiodide, and 44.5 of metallic mercury 

 are triturated with a little alcohol, protiodide is also readily formed. 



Deutiodide of mercury consists of 1 proportional of mercury to 2 

 of iodine, or of mercury 1265.822, and iodine 1578,29, or per cent. 

 44.51 and 55.49. These proportions being mixed are to be tritu- 

 rated as before, but the alcohol must be added drop by drop, and the 

 trituration continued a few moments between each addition. The 

 addition of too much alcohol renders the action so strong, that much 

 heat is evolved, the mixture even fuses, and the iodine is vapourised 

 and lost. This process succeeds very well, and gives a compound of 

 known and definite composition, although the appearance is not so 

 beautiful, nor the colour so fine, as that prepared by precipitation. 

 This is due, without doubt, to the particular state of aggregation 

 and arrangement which the particles acquire in precipitation. But 

 when both are made to undergo sublimation, they become alike in 

 every respect *. 



13. ON BORATE OP SILVER. (Rose.} 



When a concentrated solution of borax (either fused or crystal- 

 lized) is mingled with a moderately strong solution of nitrate of 

 silver, a white precipitate of borate of silver falls. Whichever way 

 the solutions are mingled the same effect takes place. When water 

 is gradually added to this precipitate, it dissolves entirely, like most 

 of the precipitates produced by alkaline borates, for very few appear 

 to be insoluble in water. Water produces no change in the consti- 

 tution of this substance ; light renders it violet or black. When 

 washed as well as may be, it was analysed, and its constitution 

 appeared to be 



Oxide of silver .... 76.9 

 Boracicacid 23.1 



100.0 



Here the acid contains only thrice the oxygen of the oxide, but in 

 borax the acid contains six times the oxygen of the base. If, there- 

 fore, borax be a neutral salt, this argentiferous compound is a subsalt. 



When a saturated solution of borax is diluted thirty or forty times, 

 so that the water present shall be enough to dissolve any borate of 

 silver formed, one of the solutions being in excess and the two being 



* Journ. de, Pharm. 1831, 456. 



