ON THE ELECTRIC COLUMN. gg^ 



It is not to be expected, that, by groping in a desultory ^^^^ ^^^ ^^^.^ 

 manner among the objects of nature, any main road of" in- ther know, 

 vestigation can be opened for the discovery of new causes ; ^^^1^'* "** 

 as their effects are so much intermixed in perceptible phe- 

 nomena, that we cannot ascend to them with certainty in a 

 retrograde manner. Many more discoveries concerning them 

 may be expected from researches carried on by connected 

 steps along the roads already opened in the maze of impon" 

 derable subbtauces, the greatest agents in the phenomena of 

 nature. 



The modifications of the su7i''s rai/s to produce heat, as agreeably lu 



followed by Mr. de Saussare and Dr. Herschel, and I may ^^at has al- 



■' * ready bee» 



say by myself; as well as the first observations made by effecied. 



Dr. Priestley on the chemical effects of light, have opened 

 one of these roads, which requires to be pursued in all its 

 ramifications. Much is to be done also concerning the na- 

 ture ofjire, i. e. the cause o? heat, or of that expansion of The causes of 

 bodies of which the thermometer is the measure; a road ^^^' 

 which has been much obstructed by the obscure idea of 

 caloric, introduced in the modern theory of chemistry, at 

 the time when several experimental philosophers were en- 

 gaged in researches concerning the nature, modifications, 

 and combinations of the expansible fluid long known under 

 the name of y?"r<?. Much more remains to be done in the electricity, 

 study of the electric fluid, its production and decomposition 

 throughout so many phenomena. Lastly, almost every 

 thing remains to be done to acquire some knowledge of a 



fluid, the existence of which is manifested by some charac- and magnet- 

 teristic effects, but which is itself totally unknown ; though '*™* 

 it cannot be without soraej and it may be a great influence 

 in terrestrial phenomena : I mean, the magnetic fluid, on 

 which I shall say here only a few words. 



Being now informed, that the motions of bodies occa- ^^^"*'^''"' 

 sioned hy amber \y\\Qx\ it has undergoney'ric^ion, of which ,ngto a p.'culi- 

 the cause was unknown to the ancients, are the effects of a "lAuid, whi-h 

 ^•11-11 1 /■ • • 1 • '^-''^ other ei- 



fluia, which has much greater functions in nature by itsfe, ts. 



compositions and decompositions; when we come to con- 

 sider the analogous, though much more limited ef^ec ts pro- 

 duced by steel bars which have undergone proper /rictions, 

 \vt are led to conclude, not only that these particular motions 



are 



