tUMINOUS ELECTRICITY. §7 



If the ftone contain filex, this earth will be feparated in the Silcx if pre&nt 

 procefs of folutiou and evaporation; and it muft be colleded ^* eparatc. 

 upon a filter, and wallied with diftilled water till the boracic 

 acid and all the fahne matter is feparated from it. 



The fluid, mixed with the water that has pafled through the Precipitate the 

 iiUer, muft be evaporated, till it is reduced to a convenient ^^^^^'^j*^^.'^" 

 quantity, fuch as that of half a pint; when it muft be faturated ammonia. 

 vvilh carbonate of ammonia, and boiled with an excefs of this 

 lalt, till all the materials that it contains, capable of being pre- 

 cipitated, have fallen to the bottom of the veflTel, 



The folution muft then be feparated by the filter, and the 

 earths and metallic oxides retained. 



It muft be mixed with nitric acid till it taftes ftrongly four, Add nitric acid 

 and evaporated till the boracic acid appears free. liquid. 



The fluid muft be patTed. through the filter, and fubje6ted Separate the 



to evaporation till it becomes dry; when, by expofure to a ^"^p^'^.^^^'^^'^^ ^ 



heat equal to 45.0'^ Farenheit, the nitrate of ammonia will be Decompofe the 



decompofed, and the nitrate of potafli or foda will remain in "'-''ate of am^ 

 '^ *^ moHia by neat, 



the velTei. 



It will be unneceifary for me to defcribe minutely the 



method of obtaining the remaining earths and metallic oxides 



free from each other, as I have ui'ed the common procelfes. 



I have feparated the al amine by folution of potafti, the lime by 



fulphuric acid^ the oxide of ir&n by fuccinate of ammonia, the 



manganefe by hydrofulphucet of potafti, and t:ie magnefta by 



pure foda. 



XX. 



SomeFaQis and Speculations on the htminom Phenomena of- Elec- 

 tricity. W. N. 



Al 



.BOUT eighteen yeaTs ago, I was coofiderably occupied Communicatloa 

 in experiments upon eledricity, many of which were comma- ^'^ '^'^ Royal 

 uicated in tl789>, to the Ro-yal Society, and were publiftiedekanclty. 

 in ihe tranfaftions. In the twenty-third feftion of that com- 

 munication, fome account is given of certain changes which 

 lake place in the luminous appearance of metallic balls when 

 eleftrified; but the phenomena were not delineated, becaufe I 

 leferved thera for another oppxjrtnnity. After fo long an in- 



